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(B yVal sender As System.Object, ByVal e As
System.EventArg s) Handles Button1.Click
Dim WOLF As New DOG
WOLF.AGE = 10
End Sub
End Class
Regards Brian
Sep 19 '06
25  1495 
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_newsgroup s" 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(B yVal sender As System.Object, ByVal e As
System.EventArg s) 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(B yVal sender As System.Object, ByVal e As
System.EventArg s) 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
"rowe_newsgroup s" <ro********@yah oo.comwrote:
>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 <bc****@es.co.n zwrote:
>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....wh y 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(B yVal sender As System.Object, ByVal e As
System.EventAr gs) 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
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_newsgroup s" 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(B yVal sender As System.Object, ByVal e As
System.EventArg s) 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(B yVal sender As System.Object, ByVal e As
>System.EventAr gs) 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
>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_newsgrou ps" 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(B yVal sender As System.Object, ByVal e
>As
>System.Eve ntArgs) 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(B yVal sender As System.Object, ByVal e
>>As
>>System.Ev entArgs) Handles Button1.Click
>>Dim WOLF As New DOG
>>WOLF.AG E = 10
>>End Sub
>>End Class
>>Regards Brian
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
"ClassPriva te" 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
circumstanc es 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
circumstance s 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 specific
custom exceptions that don't make sense apart from the "host" class.
Thanks,
Seth Rowe
GhostInAK wrote:
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
"ClassPriva te" 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
circumstance s 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
;).
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