Visibility/Access of Class Members

[Liz]

ok, this is really simple stuff, or it should be ... but I'm stuck

In a Windows Forms app, I have something resembling this:

Form1.cs
========

namespace NS

Class Form1
{
public Label label1

...

private void func1()
{
iterateRows();
}
}

Class1.cs
=========

using NS;

public class GetLabel
{
private void iterateRows()
{
Form1.label1.Te xt = "some value";
}

}
the method iterateRows is really performing a loop operation and I just want
to show values in label1 with each iteration; simple, right ? should be
but label1 is not visible from here ... I cannot find anything in the docs
which makes clear to me why Form1.label1.Te xt is not visible ... this kind
of stuff used to be a piece of cake in "C" .. but I've been away from coding
for awhile ...

I suppose I could pass a reference to label1 to iterateRows() and make this
work ? but I'd rather not and I'd like to understand why this won't work
in any case

Thanks for any help/explanations ...

L

[Liz]

"Bob Grommes" <bo*@bobgrommes .com> wrote in message
news:#P******** *****@TK2MSFTNG P15.phx.gbl...

I'm not sure why you're declaring a class member named myForm within the
Form1 class definition. As coded, it would produce a null Form
reference within the Form1 instance, and would be of no use.
correct ... it doesn't need declaration there
If label1 is still declared as a public field, myForm.label1 should be
able to be referenced. Don't conclude it's not from the absence of
Intellisense, in my experience that's only 80% reliable until the
project has had a recompile (or sometimes it starts working on its own
after some IDE background thread has caught up with reality). It's not
a good sign though. Is code completion failing in Main() or somewhere else?
You can always test by putting some dummy reference in Main() like
myForm.label1.T ext = "foo";

sure .. and that works, in the Class block, anyway .. but not in the other
..cs file which references the namespace containing the class Form1 ...

I still don't really get why I cannot perform the same test with
Form1.label1.Te xt = "foo"; ... what's the deal ? does the **IDE** actually
create an instance of the class when you type in Form1 myform = new Form1()
?? and if it hasn't seen a "new" yet it doesn't know that label1 is a
member of the class ?

static void Main()
{
myForm.label1. .... // code completion does not work here
Form1 myForm = new Form1();
myForm.label1.T ext = "XXX"; // but works here ...
Application.Run (myForm);
}
L

[Jon Skeet [C# MVP]]

Liz <li*@tiredofspa m.com> wrote:

No, because you've declared myForm to be of type Form, not type Form1.

true ... thank you; but the other code file still does not "see" the public
var label1 even though the namespace in which it "lives" is referenced

The namespace is pretty irrelevant. Could you post a short but complete
program which demonstrates the problem? If you've got a variable of
type Form1, you should be

See http://www.pobox.com/~skeet/csharp/complete.html for details of
what I mean by that.

The compiler can't know that the value won't be a reference to an
instance of a completely different form.

well, the compiler should know that it's either of type Form or of type
Form1, no ?

No - it could be any other form, as far as the compiler knows.

Declare it as Form1 (preferrably renaming it to a more useful name, of
course) and it should start working. Having said that, it's not good
practice to have public variables in the first place.

well, I'll leave the "religious" aspects of coding alone ;) this is just a
sandbox so I can nail down the functional characteristics of the language
...

It's still worth learning best practices at the same time though.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

Bob Grommes <bo*@bobgrommes .com> wrote:

I'm not sure why you're declaring a class member named myForm within the
Form1 class definition. As coded, it would produce a null Form
reference within the Form1 instance, and would be of no use.

If label1 is still declared as a public field, myForm.label1 should be
able to be referenced.

No it shouldn't - note that myForm is just a Form variable, not a Form1
variable.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Bob Grommes]

The IDE knows about the Form1 type. It doesn't need to create a
design-time instance, it just is aware of the metadata that defines
those types. (The designer probably does create a design time instance,
but that's separate from the code editor AFAIK).

At any rate ... I don't understand your final question, "I ... don't ...
get why I cannot perform ... Form1.label1.Te xt = "foo"". If that wasn't
a slip of the keyboard then I must return to my original explanation:
Form1 is a type, not an instance. The only thing you can access through
the type are static members. Instance members must be addressed through
an instance. Form1.label1 is not a valid construct because label1 is an
instance member.

If on the other hand you're asking (given a Form1 instance named myForm)
why "myForm." doesn't auto-complete, but "myForm.label1. " *does* offer
you auto-complete options -- I don't know offhand. I've seen stuff like
this intermittently and just chalk it up to One Of Those Things.
Sometimes it clears up on its own (because some background parsing
thread caught up with what you're typing) and sometimes it Just Won't
Work, At Least Not Today.

--Bob

Liz wrote:

"Bob Grommes" <bo*@bobgrommes .com> wrote in message

If label1 is still declared as a public field, myForm.label1 should be
able to be referenced. Don't conclude it's not from the absence of
Intellisens e, in my experience that's only 80% reliable until the
project has had a recompile (or sometimes it starts working on its own
after some IDE background thread has caught up with reality). It's not
a good sign though. Is code completion failing in Main() or somewhere

else?

You can always test by putting some dummy reference in Main() like
myForm.label1 .Text = "foo";

sure .. and that works, in the Class block, anyway .. but not in the other
.cs file which references the namespace containing the class Form1 ...

I still don't really get why I cannot perform the same test with
Form1.label1.Te xt = "foo"; ... what's the deal ? does the **IDE** actually
create an instance of the class when you type in Form1 myform = new Form1()
?? and if it hasn't seen a "new" yet it doesn't know that label1 is a
member of the class ?

static void Main()
{
myForm.label1. .... // code completion does not work here
Form1 myForm = new Form1();
myForm.label1.T ext = "XXX"; // but works here ...
Application.Run (myForm);
}
L