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A Question on VB Classesa class called Dog, but Visual Basic tells me that I can't enter Wolf.age....why is this? Public Class Form1 Public Class DOG Dim COLOUR As String Dim AGE As Integer Dim NAME As String End Class Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim WOLF As New DOG WOLF.AGE = 10 End Sub End Class Regards Brian
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> Public Class Form1 Your "Dim" isn't public by default, try this instead:> Public Class DOG > Dim COLOUR As String > Dim AGE As Integer > Dim NAME As String > > End Class > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > System.EventArgs) Handles Button1.Click > Dim WOLF As New DOG > WOLF.AGE = 10 > > End Sub > End Class > > Regards Brian Public COLOUR As String Public AGE As Integer Public NAME As String "Robinson" <itoldyounottospamme@nowmyinboxisfull.com> wrote in news:eeoj9j $jie$1$830fa***@news.demon.co.uk:> Your "Dim" isn't public by default, try this instead: Even better declare the variables as properties : )> > Public COLOUR As String > Public AGE As Integer > Public NAME As String Yeah...
Public members are baaaaaaaaaaaaaaaaaaaaaaaaaaaaad. Think encapsulation. If I ever found one of my coders doing Public x As Integer in a class I would force them to clean the bathrooms for a week. Show quoteHide quote "Spam Catcher" <spamhoneypot@rogers.com> wrote in message news:Xns9843AC6CD2D05usenethoneypotrogers@127.0.0.1... > "Robinson" <itoldyounottospamme@nowmyinboxisfull.com> wrote in news:eeoj9j > $jie$1$830fa***@news.demon.co.uk: > > >> Your "Dim" isn't public by default, try this instead: >> >> Public COLOUR As String >> Public AGE As Integer >> Public NAME As String > > Even better declare the variables as properties : ) > How would you re-write the DOG example?
Regards Brian Show quoteHide quote "Ray Cassick \(Home\)" <rcassickNOSPAM@enterprocity.com> wrote: >Yeah... > >Public members are baaaaaaaaaaaaaaaaaaaaaaaaaaaaad. > >Think encapsulation. > >If I ever found one of my coders doing Public x As Integer in a class I >would force them to clean the bathrooms for a week. > >"Spam Catcher" <spamhoneypot@rogers.com> wrote in message >news:Xns9843AC6CD2D05usenethoneypotrogers@127.0.0.1... >> "Robinson" <itoldyounottospamme@nowmyinboxisfull.com> wrote in news:eeoj9j >> $jie$1$830fa***@news.demon.co.uk: >> >> >>> Your "Dim" isn't public by default, try this instead: >>> >>> Public COLOUR As String >>> Public AGE As Integer >>> Public NAME As String >> >> Even better declare the variables as properties : ) >> > Spam Catcher <spamhoneypot@rogers.com> wrote:
>"Robinson" <itoldyounottospamme@nowmyinboxisfull.com> wrote in news:eeoj9j Can you give me an example using my DOG Class please.>$jie$1$830fa***@news.demon.co.uk: > > >> Your "Dim" isn't public by default, try this instead: >> >> Public COLOUR As String >> Public AGE As Integer >> Public NAME As String > >Even better declare the variables as properties : ) I'm new to this side of programming so I'm not certain what you mean by declaring the variables as properties. Regards Brian
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"Spam Catcher" <spamhoneypot@rogers.com> wrote in message Well I would have suggested that obviously, but one step at a news:Xns9843AC6CD2D05usenethoneypotrogers@127.0.0.1... > "Robinson" <itoldyounottospamme@nowmyinboxisfull.com> wrote in news:eeoj9j > $jie$1$830fa***@news.demon.co.uk: > > >> Your "Dim" isn't public by default, try this instead: >> >> Public COLOUR As String >> Public AGE As Integer >> Public NAME As String > > Even better declare the variables as properties : ) > time.......................... private m_Colour As String private m_Age As Integer private m_Name as String public property Colour As String Get return m_Colour End Get Set ( byval Value As String) m_Colour = Value End Set End property etc.................. However, in some cases this is utterly superfluous, so I wouldn't be too religious about "always" wrapping a variable inside a property. Use common sense. Properties are useful if you want to make access "readonly" or "writeonly", or if you want to change other state when a property changes, or if you want to hide the underlying representation of the object. If you aren't sure whether you want to do any of these things, use properties just in case ;). > However, in some cases this is utterly superfluous, so I wouldn't be too My only argument is that classes often vary from what they were> religious about "always" wrapping a variable inside a property. Use common > sense. originally designed for, so using properties is like preparing for the future. In my opinion properties are easier to adapt to new circumstances than variables (take overloading for example). Of course the time saved in this is lost in the time it takes to write out the property. The other huge benefit is in inheritance as you can't override member variables. I guess it's kind of like non-combat troops carrying weapons, they are rarely (if ever) going to use that weapon, but it can sure come in handy if they get attacked. Again, this is all my opinion, and I'll admit I'm a "just-in-case" kind of person :-) >The other huge benefit is in inheritance as you can't override member variables Oh yeah, I know that I didn't put the overridable keyword in myproperties - I didn't want to give Brian to much info to fast. So Brian, please add that keyword just in case! I can explain it's uses if you need me to. Thanks, Seth Rowe Robinson wrote: Show quoteHide quote > "Spam Catcher" <spamhoneypot@rogers.com> wrote in message > news:Xns9843AC6CD2D05usenethoneypotrogers@127.0.0.1... > > "Robinson" <itoldyounottospamme@nowmyinboxisfull.com> wrote in news:eeoj9j > > $jie$1$830fa***@news.demon.co.uk: > > > > > >> Your "Dim" isn't public by default, try this instead: > >> > >> Public COLOUR As String > >> Public AGE As Integer > >> Public NAME As String > > > > Even better declare the variables as properties : ) > > > > Well I would have suggested that obviously, but one step at a > time.......................... > > > private m_Colour As String > private m_Age As Integer > private m_Name as String > > public property Colour As String > > Get > return m_Colour > End Get > > Set ( byval Value As String) > m_Colour = Value > End Set > > End property > > etc.................. > > > > However, in some cases this is utterly superfluous, so I wouldn't be too > religious about "always" wrapping a variable inside a property. Use common > sense. Properties are useful if you want to make access "readonly" or > "writeonly", or if you want to change other state when a property changes, > or if you want to hide the underlying representation of the object. If you > aren't sure whether you want to do any of these things, use properties just > in case ;). > My only argument is that classes often vary from what they were I rarely overload or override properties in the majority of my classes. > originally designed for, so using properties is like preparing for the > future. In my opinion properties are easier to adapt to new > circumstances than variables (take overloading for example). However I *always* make all variables private by default and then create a public property for one if and when I need to access it from outside of the class. This is just from habit of course. In general most of this code isn't doing anything useful, however it does ensure my design doesn't get broken in some circumstances where it might otherwise (reflection for example - which I have to add I rarely use!). There is something of a discussion here (http://www.codinghorror.com/blog/archives/000654.html) about this very issue. But as I said before, I wouldn't be religious about it. I mean I still use "Goto" extensively in SQL stored procedures (but in an ON ERROR GOTO _Error kind of way) and when teaching a new "player" to the OO game, I certainly wouldn't stress the point. It's just a construct like any other. You tend to learn from experience when best to apply it and when not to, so one thing at a time: Private, the variables cannot be "seen" from outside of itself "Public" it can, "Protected" nobody knows what possible use this has ;). Well said Robinson, I think that sums it up!
> "Protected" nobody knows what possible use this has ;). It's use it to confuse newbie's of course!Actually I use them occasionally to share data through nested classes. Like in the dog example if I had dropped the Age property into a nested class I could still see a "Protected m_Birthdate as date" variable in the main class. Personally I think it should be renamed to "ClassPrivate" or something similar to stop all the confusion. So Brian, are you still with us or have we confused you to much? Thanks, Seth Rowe Robinson wrote: Show quoteHide quote > > My only argument is that classes often vary from what they were > > originally designed for, so using properties is like preparing for the > > future. In my opinion properties are easier to adapt to new > > circumstances than variables (take overloading for example). > > I rarely overload or override properties in the majority of my classes. > However I *always* make all variables private by default and then create a > public property for one if and when I need to access it from outside of the > class. This is just from habit of course. In general most of this code > isn't doing anything useful, however it does ensure my design doesn't get > broken in some circumstances where it might otherwise (reflection for > example - which I have to add I rarely use!). There is something of a > discussion here (http://www.codinghorror.com/blog/archives/000654.html) > about this very issue. But as I said before, I wouldn't be religious about > it. I mean I still use "Goto" extensively in SQL stored procedures (but in > an ON ERROR GOTO _Error kind of way) and when teaching a new "player" to the > OO game, I certainly wouldn't stress the point. It's just a construct like > any other. You tend to learn from experience when best to apply it and when > not to, so one thing at a time: Private, the variables cannot be "seen" > from outside of itself "Public" it can, "Protected" nobody knows what > possible use this has ;). Hello rowe_newsgroups,
Protected is also used for sharing variables with inherited classes. Nested classes are something to be avoided like the plague. -Boo Show quoteHide quote > Well said Robinson, I think that sums it up! > >> "Protected" nobody knows what possible use this has ;). >> > It's use it to confuse newbie's of course! > > Actually I use them occasionally to share data through nested classes. > Like in the dog example if I had dropped the Age property into a > nested class I could still see a "Protected m_Birthdate as date" > variable in the main class. Personally I think it should be renamed to > "ClassPrivate" or something similar to stop all the confusion. > > So Brian, are you still with us or have we confused you to much? > > Thanks, > > Seth Rowe > > Robinson wrote: > >>> My only argument is that classes often vary from what they were >>> originally designed for, so using properties is like preparing for >>> the future. In my opinion properties are easier to adapt to new >>> circumstances than variables (take overloading for example). >>> >> I rarely overload or override properties in the majority of my >> classes. However I *always* make all variables private by default >> and then create a public property for one if and when I need to >> access it from outside of the class. This is just from habit of >> course. In general most of this code isn't doing anything useful, >> however it does ensure my design doesn't get broken in some >> circumstances where it might otherwise (reflection for example - >> which I have to add I rarely use!). There is something of a >> discussion here >> (http://www.codinghorror.com/blog/archives/000654.html) about this >> very issue. But as I said before, I wouldn't be religious about it. >> I mean I still use "Goto" extensively in SQL stored procedures (but >> in an ON ERROR GOTO _Error kind of way) and when teaching a new >> "player" to the OO game, I certainly wouldn't stress the point. It's >> just a construct like any other. You tend to learn from experience >> when best to apply it and when not to, so one thing at a time: >> Private, the variables cannot be "seen" from outside of itself >> "Public" it can, "Protected" nobody knows what possible use this has >> ;). >> > Protected is also used for sharing variables with inherited classes. Thanks for adding that, I left it out of my original post.> Nested classes are something to be avoided like the plague. I agree, about the only time I nest classes is to create very specificcustom exceptions that don't make sense apart from the "host" class. Thanks, Seth Rowe GhostInAK wrote: Show quoteHide quote > Hello rowe_newsgroups, > > Protected is also used for sharing variables with inherited classes. > Nested classes are something to be avoided like the plague. > > -Boo > > > > Well said Robinson, I think that sums it up! > > > >> "Protected" nobody knows what possible use this has ;). > >> > > It's use it to confuse newbie's of course! > > > > Actually I use them occasionally to share data through nested classes. > > Like in the dog example if I had dropped the Age property into a > > nested class I could still see a "Protected m_Birthdate as date" > > variable in the main class. Personally I think it should be renamed to > > "ClassPrivate" or something similar to stop all the confusion. > > > > So Brian, are you still with us or have we confused you to much? > > > > Thanks, > > > > Seth Rowe > > > > Robinson wrote: > > > >>> My only argument is that classes often vary from what they were > >>> originally designed for, so using properties is like preparing for > >>> the future. In my opinion properties are easier to adapt to new > >>> circumstances than variables (take overloading for example). > >>> > >> I rarely overload or override properties in the majority of my > >> classes. However I *always* make all variables private by default > >> and then create a public property for one if and when I need to > >> access it from outside of the class. This is just from habit of > >> course. In general most of this code isn't doing anything useful, > >> however it does ensure my design doesn't get broken in some > >> circumstances where it might otherwise (reflection for example - > >> which I have to add I rarely use!). There is something of a > >> discussion here > >> (http://www.codinghorror.com/blog/archives/000654.html) about this > >> very issue. But as I said before, I wouldn't be religious about it. > >> I mean I still use "Goto" extensively in SQL stored procedures (but > >> in an ON ERROR GOTO _Error kind of way) and when teaching a new > >> "player" to the OO game, I certainly wouldn't stress the point. It's > >> just a construct like any other. You tend to learn from experience > >> when best to apply it and when not to, so one thing at a time: > >> Private, the variables cannot be "seen" from outside of itself > >> "Public" it can, "Protected" nobody knows what possible use this has > >> ;). > >> Because the property variables aren't visible. Declare them with the
public keyword instead of dim (which is private by default). i.e. The following should work just fine. Public Class Form1 Public Class DOG Public COLOUR As String Public AGE As Integer Public NAME As String End Class Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim WOLF As New DOG WOLF.AGE = 10 End Sub End Class Brian wrote: Show quoteHide quote > Can some one please tell me what I'm doing wrong. I'm trying to create > a class called Dog, but Visual Basic tells me that I can't enter > Wolf.age....why is this? > > Public Class Form1 > Public Class DOG > Dim COLOUR As String > Dim AGE As Integer > Dim NAME As String > > End Class > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > System.EventArgs) Handles Button1.Click > Dim WOLF As New DOG > WOLF.AGE = 10 > > End Sub > End Class > > Regards Brian Brian,
While it may work, it's ugly as sin. You should separate your DOG class out into a different file. Also, instead of using fields publicly you should make them private and provide public properties instead. -Boo Show quoteHide quote > Because the property variables aren't visible. Declare them with the > public keyword instead of dim (which is private by default). i.e. The > following should work just fine. > > Public Class Form1 > Public Class DOG > Public COLOUR As String > Public AGE As Integer > Public NAME As String > End Class > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > System.EventArgs) Handles Button1.Click > Dim WOLF As New DOG > WOLF.AGE = 10 > End Sub > End Class > Brian wrote: > >> Can some one please tell me what I'm doing wrong. I'm trying to >> create a class called Dog, but Visual Basic tells me that I can't >> enter Wolf.age....why is this? >> >> Public Class Form1 >> Public Class DOG >> Dim COLOUR As String >> Dim AGE As Integer >> Dim NAME As String >> End Class >> >> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As >> System.EventArgs) Handles Button1.Click >> Dim WOLF As New DOG >> WOLF.AGE = 10 >> End Sub >> End Class >> Regards Brian >> Why separate the dog class to a different file...moving it to after the end
of the form class should work also. Why use a private variable then a property to read/write it if no special actions are needed for the read and write? -- Show quoteHide quoteDennis in Houston "GhostInAK" wrote: > Brian, > > While it may work, it's ugly as sin. You should separate your DOG class > out into a different file. Also, instead of using fields publicly you should > make them private and provide public properties instead. > > -Boo > > > Because the property variables aren't visible. Declare them with the > > public keyword instead of dim (which is private by default). i.e. The > > following should work just fine. > > > > Public Class Form1 > > Public Class DOG > > Public COLOUR As String > > Public AGE As Integer > > Public NAME As String > > End Class > > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > > System.EventArgs) Handles Button1.Click > > Dim WOLF As New DOG > > WOLF.AGE = 10 > > End Sub > > End Class > > Brian wrote: > > > >> Can some one please tell me what I'm doing wrong. I'm trying to > >> create a class called Dog, but Visual Basic tells me that I can't > >> enter Wolf.age....why is this? > >> > >> Public Class Form1 > >> Public Class DOG > >> Dim COLOUR As String > >> Dim AGE As Integer > >> Dim NAME As String > >> End Class > >> > >> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > >> System.EventArgs) Handles Button1.Click > >> Dim WOLF As New DOG > >> WOLF.AGE = 10 > >> End Sub > >> End Class > >> Regards Brian > >> > > > > Why use a private variable then a property to read/write it if no special The dog class isn't a real good example, but normally you want more> actions are needed for the read and write? control over the property (validation for example). Just like Option Strict On isn't always needed (and requires more code) using properties instead of variables is just good programming practice. IMHO it improves the readablity of the code and makes it much much easier to update and/or modify. > Why separate the dog class to a different file...moving it to after the end Again, this is not a good example but moving it to a different file is> of the form class should work also. mainly for code reuse (OOP). If this was a more "advanced" class that would be used in multiple solutions, being in the form's class file wouldn't be a good idea. You would have to add an unneeded and unwanted class (the form class) just to get to the advanced class. In my opinion you shouldn't group unrelated classes in the same file. Pretty much the suggestions were mainly to teach someone new to vb classes good programming practices, not to say that what he had was wrong. Hope that clarifies some things, Seth Rowe Dennis wrote: Show quoteHide quote > Why separate the dog class to a different file...moving it to after the end > of the form class should work also. > > Why use a private variable then a property to read/write it if no special > actions are needed for the read and write? > > -- > Dennis in Houston > > > "GhostInAK" wrote: > > > Brian, > > > > While it may work, it's ugly as sin. You should separate your DOG class > > out into a different file. Also, instead of using fields publicly you should > > make them private and provide public properties instead. > > > > -Boo > > > > > Because the property variables aren't visible. Declare them with the > > > public keyword instead of dim (which is private by default). i.e. The > > > following should work just fine. > > > > > > Public Class Form1 > > > Public Class DOG > > > Public COLOUR As String > > > Public AGE As Integer > > > Public NAME As String > > > End Class > > > > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > > > System.EventArgs) Handles Button1.Click > > > Dim WOLF As New DOG > > > WOLF.AGE = 10 > > > End Sub > > > End Class > > > Brian wrote: > > > > > >> Can some one please tell me what I'm doing wrong. I'm trying to > > >> create a class called Dog, but Visual Basic tells me that I can't > > >> enter Wolf.age....why is this? > > >> > > >> Public Class Form1 > > >> Public Class DOG > > >> Dim COLOUR As String > > >> Dim AGE As Integer > > >> Dim NAME As String > > >> End Class > > >> > > >> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > > >> System.EventArgs) Handles Button1.Click > > >> Dim WOLF As New DOG > > >> WOLF.AGE = 10 > > >> End Sub > > >> End Class > > >> Regards Brian > > >> > > > > > > Could you give me an example as I'm new to Classes.
Regards Brian Show quoteHide quote "rowe_newsgroups" <rowe_em***@yahoo.com> wrote: >> Why use a private variable then a property to read/write it if no special >> actions are needed for the read and write? > >The dog class isn't a real good example, but normally you want more >control over the property (validation for example). Just like Option >Strict On isn't always needed (and requires more code) using properties >instead of variables is just good programming practice. IMHO it >improves the readablity of the code and makes it much much easier to >update and/or modify. > >> Why separate the dog class to a different file...moving it to after the end >> of the form class should work also. > >Again, this is not a good example but moving it to a different file is >mainly for code reuse (OOP). If this was a more "advanced" class that >would be used in multiple solutions, being in the form's class file >wouldn't be a good idea. You would have to add an unneeded and unwanted >class (the form class) just to get to the advanced class. In my opinion >you shouldn't group unrelated classes in the same file. > >Pretty much the suggestions were mainly to teach someone new to vb >classes good programming practices, not to say that what he had was >wrong. > >Hope that clarifies some things, > >Seth Rowe > >Dennis wrote: >> Why separate the dog class to a different file...moving it to after the end >> of the form class should work also. >> >> Why use a private variable then a property to read/write it if no special >> actions are needed for the read and write? >> >> -- >> Dennis in Houston >> >> >> "GhostInAK" wrote: >> >> > Brian, >> > >> > While it may work, it's ugly as sin. You should separate your DOG class >> > out into a different file. Also, instead of using fields publicly you should >> > make them private and provide public properties instead. >> > > >> > -Boo >> > >> > > Because the property variables aren't visible. Declare them with the >> > > public keyword instead of dim (which is private by default). i.e. The >> > > following should work just fine. >> > > >> > > Public Class Form1 >> > > Public Class DOG >> > > Public COLOUR As String >> > > Public AGE As Integer >> > > Public NAME As String >> > > End Class >> > > >> > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As >> > > System.EventArgs) Handles Button1.Click >> > > Dim WOLF As New DOG >> > > WOLF.AGE = 10 >> > > End Sub >> > > End Class >> > > Brian wrote: >> > > >> > >> Can some one please tell me what I'm doing wrong. I'm trying to >> > >> create a class called Dog, but Visual Basic tells me that I can't >> > >> enter Wolf.age....why is this? >> > >> >> > >> Public Class Form1 >> > >> Public Class DOG >> > >> Dim COLOUR As String >> > >> Dim AGE As Integer >> > >> Dim NAME As String >> > >> End Class >> > >> >> > >> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As >> > >> System.EventArgs) Handles Button1.Click >> > >> Dim WOLF As New DOG >> > >> WOLF.AGE = 10 >> > >> End Sub >> > >> End Class >> > >> Regards Brian >> > >> >> > >> > >> > I am having trouble finding uderstanding why using a public variable instead
of a property with get and set is bad programming practice. In fact, there are a lot of properties that don't do anything that requres a get or set and it's much easier to accumulate these just below the class statement as public variables as you dont' have to scroll down thru a lot of screens to read the code. Each to his own I guess. What's good programming practice to one is not to another. -- Show quoteHide quoteDennis in Houston "rowe_newsgroups" wrote: > > Why use a private variable then a property to read/write it if no special > > actions are needed for the read and write? > > The dog class isn't a real good example, but normally you want more > control over the property (validation for example). Just like Option > Strict On isn't always needed (and requires more code) using properties > instead of variables is just good programming practice. IMHO it > improves the readablity of the code and makes it much much easier to > update and/or modify. > > > Why separate the dog class to a different file...moving it to after the end > > of the form class should work also. > > Again, this is not a good example but moving it to a different file is > mainly for code reuse (OOP). If this was a more "advanced" class that > would be used in multiple solutions, being in the form's class file > wouldn't be a good idea. You would have to add an unneeded and unwanted > class (the form class) just to get to the advanced class. In my opinion > you shouldn't group unrelated classes in the same file. > > Pretty much the suggestions were mainly to teach someone new to vb > classes good programming practices, not to say that what he had was > wrong. > > Hope that clarifies some things, > > Seth Rowe > > Dennis wrote: > > Why separate the dog class to a different file...moving it to after the end > > of the form class should work also. > > > > Why use a private variable then a property to read/write it if no special > > actions are needed for the read and write? > > > > -- > > Dennis in Houston > > > > > > "GhostInAK" wrote: > > > > > Brian, > > > > > > While it may work, it's ugly as sin. You should separate your DOG class > > > out into a different file. Also, instead of using fields publicly you should > > > make them private and provide public properties instead. > > > > > > > -Boo > > > > > > > Because the property variables aren't visible. Declare them with the > > > > public keyword instead of dim (which is private by default). i.e. The > > > > following should work just fine. > > > > > > > > Public Class Form1 > > > > Public Class DOG > > > > Public COLOUR As String > > > > Public AGE As Integer > > > > Public NAME As String > > > > End Class > > > > > > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > > > > System.EventArgs) Handles Button1.Click > > > > Dim WOLF As New DOG > > > > WOLF.AGE = 10 > > > > End Sub > > > > End Class > > > > Brian wrote: > > > > > > > >> Can some one please tell me what I'm doing wrong. I'm trying to > > > >> create a class called Dog, but Visual Basic tells me that I can't > > > >> enter Wolf.age....why is this? > > > >> > > > >> Public Class Form1 > > > >> Public Class DOG > > > >> Dim COLOUR As String > > > >> Dim AGE As Integer > > > >> Dim NAME As String > > > >> End Class > > > >> > > > >> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > > > >> System.EventArgs) Handles Button1.Click > > > >> Dim WOLF As New DOG > > > >> WOLF.AGE = 10 > > > >> End Sub > > > >> End Class > > > >> Regards Brian > > > >> > > > > > > > > > > > > I am having trouble finding uderstanding why using a public variable instead In my experience classes tend to "morph" over time. This includes> of a property with get and set is bad programming practice. In fact, there > are a lot of properties that don't do anything that requres a get or set inheriting the class and overriding various methods. Or adding overloading versions of properties. Or implementing try catch blocks. And so on and so on. All of the above examples are common things that are done with/to classes, and none are possible with with variables. This is why using properties can make your life (and your fellow coder's lives) much easier in the long run. It's kind of like the object orientated programming ideals, it is nothing more than a set of good ideas. You don't need to use any of them to make good programs, and in many causes it takes longer to build the program and requires more code. But in the long run OOP makes things much easier on you, through code reuse and everything else it offers. I guess you could say using properties is more conformant to OOP standards than using variables. > it's much easier to accumulate these just below the class statement as public That's what the new outlining feature is for! Besides if you're just> variables as you dont' have to scroll down thru a lot of screens to read the > code. using standard get set property blocks why do you need to read through the code anyway? I say just type up the property, hit the " - " button to hide it, and forget it. Thanks, Seth Rowe Dennis wrote: Show quoteHide quote > I am having trouble finding uderstanding why using a public variable instead > of a property with get and set is bad programming practice. In fact, there > are a lot of properties that don't do anything that requres a get or set and > it's much easier to accumulate these just below the class statement as public > variables as you dont' have to scroll down thru a lot of screens to read the > code. > > Each to his own I guess. What's good programming practice to one is not to > another. > -- > Dennis in Houston > > > "rowe_newsgroups" wrote: > > > > Why use a private variable then a property to read/write it if no special > > > actions are needed for the read and write? > > > > The dog class isn't a real good example, but normally you want more > > control over the property (validation for example). Just like Option > > Strict On isn't always needed (and requires more code) using properties > > instead of variables is just good programming practice. IMHO it > > improves the readablity of the code and makes it much much easier to > > update and/or modify. > > > > > Why separate the dog class to a different file...moving it to after the end > > > of the form class should work also. > > > > Again, this is not a good example but moving it to a different file is > > mainly for code reuse (OOP). If this was a more "advanced" class that > > would be used in multiple solutions, being in the form's class file > > wouldn't be a good idea. You would have to add an unneeded and unwanted > > class (the form class) just to get to the advanced class. In my opinion > > you shouldn't group unrelated classes in the same file. > > > > Pretty much the suggestions were mainly to teach someone new to vb > > classes good programming practices, not to say that what he had was > > wrong. > > > > Hope that clarifies some things, > > > > Seth Rowe > > > > Dennis wrote: > > > Why separate the dog class to a different file...moving it to after the end > > > of the form class should work also. > > > > > > Why use a private variable then a property to read/write it if no special > > > actions are needed for the read and write? > > > > > > -- > > > Dennis in Houston > > > > > > > > > "GhostInAK" wrote: > > > > > > > Brian, > > > > > > > > While it may work, it's ugly as sin. You should separate your DOG class > > > > out into a different file. Also, instead of using fields publicly you should > > > > make them private and provide public properties instead. > > > > > > > > > > -Boo > > > > > > > > > Because the property variables aren't visible. Declare them with the > > > > > public keyword instead of dim (which is private by default). i.e. The > > > > > following should work just fine. > > > > > > > > > > Public Class Form1 > > > > > Public Class DOG > > > > > Public COLOUR As String > > > > > Public AGE As Integer > > > > > Public NAME As String > > > > > End Class > > > > > > > > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > > > > > System.EventArgs) Handles Button1.Click > > > > > Dim WOLF As New DOG > > > > > WOLF.AGE = 10 > > > > > End Sub > > > > > End Class > > > > > Brian wrote: > > > > > > > > > >> Can some one please tell me what I'm doing wrong. I'm trying to > > > > >> create a class called Dog, but Visual Basic tells me that I can't > > > > >> enter Wolf.age....why is this? > > > > >> > > > > >> Public Class Form1 > > > > >> Public Class DOG > > > > >> Dim COLOUR As String > > > > >> Dim AGE As Integer > > > > >> Dim NAME As String > > > > >> End Class > > > > >> > > > > >> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > > > > >> System.EventArgs) Handles Button1.Click > > > > >> Dim WOLF As New DOG > > > > >> WOLF.AGE = 10 > > > > >> End Sub > > > > >> End Class > > > > >> Regards Brian > > > > >> > > > > > > > > > > > > > > > > Hello rowe_newsgroups,
Seth is entirely correct in his assesment. I work on medium to large projects everyday. Properties are a must. The code becomes unmaintainable without them. The instant you have to add error or bounds checking, data transformations, or simply causing something to be readonly.. all common things to do with properties, you've broken your interface. Everyone was hitting Class.Variable... now.. we add bounds checking, and the business rules say the bounds checking is manditory.. so now we MUST hide the Variable (since it can't provide the checks).. now.. that class uses the Variable extensively.. do we rename the variable, and expose a property of its old name? Or do we leave the variable and create a property of a new name? Either way somebody's code is gonna have to change. No. We do things right from the start and anything exposed through the public interface is done via proeprties, not variables. -Boo Show quoteHide quote >> I am having trouble finding uderstanding why using a public variable >> instead of a property with get and set is bad programming practice. >> In fact, there are a lot of properties that don't do anything that >> requres a get or set >> > In my experience classes tend to "morph" over time. This includes > inheriting the class and overriding various methods. Or adding > overloading versions of properties. Or implementing try catch blocks. > And so on and so on. All of the above examples are common things that > are done with/to classes, and none are possible with with variables. > This is why using properties can make your life (and your fellow > coder's lives) much easier in the long run. It's kind of like the > object orientated programming ideals, it is nothing more than a set of > good ideas. You don't need to use any of them to make good programs, > and in many causes it takes longer to build the program and requires > more code. But in the long run OOP makes things much easier on you, > through code reuse and everything else it offers. I guess you could > say using properties is more conformant to OOP standards than using > variables. > >> it's much easier to accumulate these just below the class statement >> as public variables as you dont' have to scroll down thru a lot of >> screens to read the code. >> > That's what the new outlining feature is for! Besides if you're just > using standard get set property blocks why do you need to read through > the code anyway? I say just type up the property, hit the " - " button > to hide it, and forget it. > > Thanks, > > Seth Rowe > > Dennis wrote: > >> I am having trouble finding uderstanding why using a public variable >> instead of a property with get and set is bad programming practice. >> In fact, there are a lot of properties that don't do anything that >> requres a get or set and it's much easier to accumulate these just >> below the class statement as public variables as you dont' have to >> scroll down thru a lot of screens to read the code. >> >> Each to his own I guess. What's good programming practice to one is >> not to >> another. >> -- >> Dennis in Houston >> "rowe_newsgroups" wrote: >> >>>> Why use a private variable then a property to read/write it if no >>>> special actions are needed for the read and write? >>>> >>> The dog class isn't a real good example, but normally you want more >>> control over the property (validation for example). Just like Option >>> Strict On isn't always needed (and requires more code) using >>> properties instead of variables is just good programming practice. >>> IMHO it improves the readablity of the code and makes it much much >>> easier to update and/or modify. >>> >>>> Why separate the dog class to a different file...moving it to after >>>> the end of the form class should work also. >>>> >>> Again, this is not a good example but moving it to a different file >>> is mainly for code reuse (OOP). If this was a more "advanced" class >>> that would be used in multiple solutions, being in the form's class >>> file wouldn't be a good idea. You would have to add an unneeded and >>> unwanted class (the form class) just to get to the advanced class. >>> In my opinion you shouldn't group unrelated classes in the same >>> file. >>> >>> Pretty much the suggestions were mainly to teach someone new to vb >>> classes good programming practices, not to say that what he had was >>> wrong. >>> >>> Hope that clarifies some things, >>> >>> Seth Rowe >>> >>> Dennis wrote: >>> >>>> Why separate the dog class to a different file...moving it to after >>>> the end of the form class should work also. >>>> >>>> Why use a private variable then a property to read/write it if no >>>> special actions are needed for the read and write? >>>> >>>> -- >>>> Dennis in Houston >>>> "GhostInAK" wrote: >>>> >>>>> Brian, >>>>> >>>>> While it may work, it's ugly as sin. You should separate your DOG >>>>> class >>>>> out into a different file. Also, instead of using fields publicly >>>>> you should >>>>> make them private and provide public properties instead. >>>>> -Boo >>>>> >>>>>> Because the property variables aren't visible. Declare them with >>>>>> the public keyword instead of dim (which is private by default). >>>>>> i.e. The following should work just fine. >>>>>> >>>>>> Public Class Form1 >>>>>> Public Class DOG >>>>>> Public COLOUR As String >>>>>> Public AGE As Integer >>>>>> Public NAME As String >>>>>> End Class >>>>>> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e >>>>>> As >>>>>> System.EventArgs) Handles Button1.Click >>>>>> Dim WOLF As New DOG >>>>>> WOLF.AGE = 10 >>>>>> End Sub >>>>>> End Class >>>>>> Brian wrote: >>>>>>> Can some one please tell me what I'm doing wrong. I'm trying to >>>>>>> create a class called Dog, but Visual Basic tells me that I >>>>>>> can't enter Wolf.age....why is this? >>>>>>> >>>>>>> Public Class Form1 >>>>>>> Public Class DOG >>>>>>> Dim COLOUR As String >>>>>>> Dim AGE As Integer >>>>>>> Dim NAME As String >>>>>>> End Class >>>>>>> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e >>>>>>> As >>>>>>> System.EventArgs) Handles Button1.Click >>>>>>> Dim WOLF As New DOG >>>>>>> WOLF.AGE = 10 >>>>>>> End Sub >>>>>>> End Class >>>>>>> Regards Brian I'm just using the DOG class as an example to better understand how
classes work in VB. Dennis <Den***@discussions.microsoft.com> wrote: Show quoteHide quote >Why separate the dog class to a different file...moving it to after the end >of the form class should work also. > >Why use a private variable then a property to read/write it if no special >actions are needed for the read and write? >Do you mean has a class file called DOG.vb with Get and Set Yes>statements? Here's a very simple example. Note, I do no validation or error trapping in this sample, you should add this yourself. ' Aircode Warning Public Class Dog ' Use an enum if you want to control allowed values for Color Public Enum ColorEnum Brown Black White Golden ' ...etc End Enum Private m_Color As ColorEnum Private m_BirthDate As Date Private m_Name As String Public Property Color() As ColorEnum Get Return m_Color End Get Set(ByVal value As ColorEnum) m_Color = value End Set End Property Public Property Name() As String Get Return m_Name End Get Set(ByVal value As String) m_Name = value End Set End Property Public Property Birthdate() As Date Get Return m_BirthDate End Get Set(ByVal value As Date) m_BirthDate = value End Set End Property ' This is a better way to get the age property (IMHO) Public ReadOnly Property Age() As Integer Get Return DateDiff(DateInterval.Year, Now(), m_BirthDate) End Get End Property End Class Thanks, Seth Rowe Brian wrote: Show quoteHide quote > I'm just using the DOG class as an example to better understand how > classes work in VB. > > Dennis <Den***@discussions.microsoft.com> wrote: > > >Why separate the dog class to a different file...moving it to after the end > >of the form class should work also. > > > >Why use a private variable then a property to read/write it if no special > >actions are needed for the read and write? Do you mean has a class file called DOG.vb with Get and Set
statements? Regards Brian GhostInAK <ghosti***@gmail.com> wrote: Show quoteHide quote >Brian, > >While it may work, it's ugly as sin. You should separate your DOG class >out into a different file. Also, instead of using fields publicly you should >make them private and provide public properties instead. > >-Boo > >> Because the property variables aren't visible. Declare them with the >> public keyword instead of dim (which is private by default). i.e. The >> following should work just fine. >> >> Public Class Form1 >> Public Class DOG >> Public COLOUR As String >> Public AGE As Integer >> Public NAME As String >> End Class >> >> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As >> System.EventArgs) Handles Button1.Click >> Dim WOLF As New DOG >> WOLF.AGE = 10 >> End Sub >> End Class >> Brian wrote: >> >>> Can some one please tell me what I'm doing wrong. I'm trying to >>> create a class called Dog, but Visual Basic tells me that I can't >>> enter Wolf.age....why is this? >>> >>> Public Class Form1 >>> Public Class DOG >>> Dim COLOUR As String >>> Dim AGE As Integer >>> Dim NAME As String >>> End Class >>> >>> Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As >>> System.EventArgs) Handles Button1.Click >>> Dim WOLF As New DOG >>> WOLF.AGE = 10 >>> End Sub >>> End Class >>> Regards Brian >>> > Thanks for all your repies.
If someone could give me easy to follow examples of using Classes in Visual Basic then that would be helpful. Perhaps a web address the has code for a VB program that I could download or if you have code that could be ziped up and sent to me by e-mail for me to study then this would be helpful to learn more abolut how to use classes in VB program code thanks. Regards Brian Brian <bcl***@es.co.nz> wrote: Show quoteHide quote >Can some one please tell me what I'm doing wrong. I'm trying to create >a class called Dog, but Visual Basic tells me that I can't enter >Wolf.age....why is this? > >Public Class Form1 > Public Class DOG > Dim COLOUR As String > Dim AGE As Integer > Dim NAME As String > > End Class > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As >System.EventArgs) Handles Button1.Click > Dim WOLF As New DOG > WOLF.AGE = 10 > > End Sub >End Class > >Regards Brian > If someone could give me easy to follow examples of using Classes in What's your programming background? Maybe we could recomend some> Visual Basic then that would be helpful. books/websites that might help if we knew what you do and don't know. > Perhaps a web address the has code for a VB program that I could www.codeproject.com> download or if you have code that could be ziped up and sent to me by > e-mail for me to study then this would be helpful to learn more abolut > how to use classes in VB program code thanks. Download some beginner classes and just start stepping through the code to see how they use classes. Thanks, Seth Rowe Brian wrote: Show quoteHide quote > Thanks for all your repies. > > If someone could give me easy to follow examples of using Classes in > Visual Basic then that would be helpful. > Perhaps a web address the has code for a VB program that I could > download or if you have code that could be ziped up and sent to me by > e-mail for me to study then this would be helpful to learn more abolut > how to use classes in VB program code thanks. > > Regards Brian > > > > > Brian <bcl***@es.co.nz> wrote: > > >Can some one please tell me what I'm doing wrong. I'm trying to create > >a class called Dog, but Visual Basic tells me that I can't enter > >Wolf.age....why is this? > > > >Public Class Form1 > > Public Class DOG > > Dim COLOUR As String > > Dim AGE As Integer > > Dim NAME As String > > > > End Class > > > > > > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As > >System.EventArgs) Handles Button1.Click > > Dim WOLF As New DOG > > WOLF.AGE = 10 > > > > End Sub > >End Class > > > >Regards Brian Thanks rowe and others for your help.
I know the basics of programming in Visual Basic but I want to get a more deeper understanding of this language. Regards Brian Show quoteHide quote "rowe_newsgroups" <rowe_em***@yahoo.com> wrote: >> If someone could give me easy to follow examples of using Classes in >> Visual Basic then that would be helpful. > >What's your programming background? Maybe we could recomend some >books/websites that might help if we knew what you do and don't know. > >> Perhaps a web address the has code for a VB program that I could >> download or if you have code that could be ziped up and sent to me by >> e-mail for me to study then this would be helpful to learn more abolut >> how to use classes in VB program code thanks. > >www.codeproject.com > >Download some beginner classes and just start stepping through the code >to see how they use classes. > >Thanks, > >Seth Rowe > >Brian wrote: >> Thanks for all your repies. >> >> If someone could give me easy to follow examples of using Classes in >> Visual Basic then that would be helpful. >> Perhaps a web address the has code for a VB program that I could >> download or if you have code that could be ziped up and sent to me by >> e-mail for me to study then this would be helpful to learn more abolut >> how to use classes in VB program code thanks. >> >> Regards Brian >> >> >> >> >> Brian <bcl***@es.co.nz> wrote: >> >> >Can some one please tell me what I'm doing wrong. I'm trying to create >> >a class called Dog, but Visual Basic tells me that I can't enter >> >Wolf.age....why is this? >> > >> >Public Class Form1 >> > Public Class DOG >> > Dim COLOUR As String >> > Dim AGE As Integer >> > Dim NAME As String >> > >> > End Class >> > >> > >> > Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As >> >System.EventArgs) Handles Button1.Click >> > Dim WOLF As New DOG >> > WOLF.AGE = 10 >> > >> > End Sub >> >End Class >> > >> >Regards Brian 
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