form object

[James]

I am trying to a add a method to a helper class library I built that will
fade out the current form. My code is this:

public void fade(object currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

This works great if I go ahead and put it in my exit event on the form like
this:

int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
this.Opacity = i;
while(z<10000)
{
z++;
}
}
this.Close();

When I have it in my helper Class Library it tells me that "'object' does
not contain a definition for 'Opacity'". Am I doing this wrong or is this not
allowed?

Thank you for your help!

[Nicholas Paldino [.NET/C# MVP]]

James,

Well, you are passing in an object. In .NET, an object only has four
methods on it.

I assume you are coming from VB, which allows for calling
methods/properties without knowing the actual type. VB would then call the
property/method (slower than if it knew the type), not caring about the
type.

Needless to say, C# does not allow this. However, since you want to do
this on forms, you can easily change your type declaration to Form, like so:

public void fade(Form currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

And then it will compile.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"James" <Ja***@discussi ons.microsoft.c om> wrote in message
news:42******** *************** ***********@mic rosoft.com...

I am trying to a add a method to a helper class library I built that will
fade out the current form. My code is this:

public void fade(object currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

This works great if I go ahead and put it in my exit event on the form
like
this:

int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
this.Opacity = i;
while(z<10000)
{
z++;
}
}
this.Close();

When I have it in my helper Class Library it tells me that "'object' does
not contain a definition for 'Opacity'". Am I doing this wrong or is this
not
allowed?

Thank you for your help!

[James]

Nicholas,

Yes, I am "coming from VB". I had tried doing it as (Form currentForm)
and when I compiled I would get this message: "The type or namespace name
'Form' could not be found (ar you missing a using directive or an assembly
reference?)".

James

"Nicholas Paldino [.NET/C# MVP]" wrote:

James,

Well, you are passing in an object. In .NET, an object only has four
methods on it.

I assume you are coming from VB, which allows for calling
methods/properties without knowing the actual type. VB would then call the
property/method (slower than if it knew the type), not caring about the
type.

Needless to say, C# does not allow this. However, since you want to do
this on forms, you can easily change your type declaration to Form, like so:

public void fade(Form currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

And then it will compile.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"James" <Ja***@discussi ons.microsoft.c om> wrote in message
news:42******** *************** ***********@mic rosoft.com...

I am trying to a add a method to a helper class library I built that will
fade out the current form. My code is this:

public void fade(object currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

This works great if I go ahead and put it in my exit event on the form
like
this:

int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
this.Opacity = i;
while(z<10000)
{
z++;
}
}
this.Close();

When I have it in my helper Class Library it tells me that "'object' does
not contain a definition for 'Opacity'". Am I doing this wrong or is this
not
allowed?

Thank you for your help!

[Bob Grommes]

When you have the code pasted into your form event, "this" is a Form and
has Opacity.

The type "object" does not have an opacity property, hence your error.
You would have to unbox the form instance you pass in -- a costly and
unnecessary step.

Typically you would instead have this signature:

public static void Fade(Windows.Fo rms.Form currentForm)

By making it static in some class, call it MyUtils, you can call it from
any form like so:

MyUtils.Fade(th is);

Alternately, you could make it a protected member of a parent form class
that your form inherits from, and eliminate passing the argument at all,
because the code internal to the routine could just use "this". So the
call would be:

this.Fade();

or simply,

Fade();

--Bob

James wrote:

I am trying to a add a method to a helper class library I built that will
fade out the current form. My code is this:

public void fade(object currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

This works great if I go ahead and put it in my exit event on the form like
this:

int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
this.Opacity = i;
while(z<10000)
{
z++;
}
}
this.Close();

When I have it in my helper Class Library it tells me that "'object' does
not contain a definition for 'Opacity'". Am I doing this wrong or is this not
allowed?

Thank you for your help!

[Bob Grommes]

Your utility class needs a reference to System.Windows. Forms, and it
needs a using directive for same, or else a fully qualified reference to
the System.Windows. Forms.Form class. ("using" in this context is
equivalent to "Imports" in VB.NET).

--Bob

James wrote:

Nicholas,

Yes, I am "coming from VB". I had tried doing it as (Form currentForm)
and when I compiled I would get this message: "The type or namespace name
'Form' could not be found (ar you missing a using directive or an assembly
reference?)".

James

[Nicholas Paldino [.NET/C# MVP]]

James,

When you do that, you will have to add a reference to
System.Windows. Forms.dll to your project (if it is not there already).

Then, at the top of your file, do this:

using System.Windows. Forms;
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"James" <Ja***@discussi ons.microsoft.c om> wrote in message
news:5F******** *************** ***********@mic rosoft.com...

Nicholas,

Yes, I am "coming from VB". I had tried doing it as (Form currentForm)
and when I compiled I would get this message: "The type or namespace name
'Form' could not be found (ar you missing a using directive or an assembly
reference?)".

James

"Nicholas Paldino [.NET/C# MVP]" wrote:

James,

Well, you are passing in an object. In .NET, an object only has four
methods on it.

I assume you are coming from VB, which allows for calling
methods/properties without knowing the actual type. VB would then call
the
property/method (slower than if it knew the type), not caring about the
type.

Needless to say, C# does not allow this. However, since you want to
do
this on forms, you can easily change your type declaration to Form, like
so:

public void fade(Form currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

And then it will compile.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"James" <Ja***@discussi ons.microsoft.c om> wrote in message
news:42******** *************** ***********@mic rosoft.com...

>I am trying to a add a method to a helper class library I built that
>will
> fade out the current form. My code is this:
>
> public void fade(object currentForm)
> {
> int z = 0;
> for(double i=1.0; i> 0; i-=.1)
> {
> currentForm.Opa city = i;
> while(z<10000)
> {
> z++;
> }
> }
> }
>
> This works great if I go ahead and put it in my exit event on the form
> like
> this:
>
> int z = 0;
> for(double i=1.0; i> 0; i-=.1)
> {
> this.Opacity = i;
> while(z<10000)
> {
> z++;
> }
> }
> this.Close();
>
> When I have it in my helper Class Library it tells me that "'object'
> does
> not contain a definition for 'Opacity'". Am I doing this wrong or is
> this
> not
> allowed?
>
> Thank you for your help!

[James]

Bob & Nicholas,

Thank you for your help. I added the reference of System.Windows. Forms to
my helper class library and it works great! Just what I wanted to do! Now I
can call it from any form.

Thank you!

James

"Bob Grommes" wrote:

When you have the code pasted into your form event, "this" is a Form and
has Opacity.

The type "object" does not have an opacity property, hence your error.
You would have to unbox the form instance you pass in -- a costly and
unnecessary step.

Typically you would instead have this signature:

public static void Fade(Windows.Fo rms.Form currentForm)

By making it static in some class, call it MyUtils, you can call it from
any form like so:

MyUtils.Fade(th is);

Alternately, you could make it a protected member of a parent form class
that your form inherits from, and eliminate passing the argument at all,
because the code internal to the routine could just use "this". So the
call would be:

this.Fade();

or simply,

Fade();

--Bob

James wrote:

I am trying to a add a method to a helper class library I built that will
fade out the current form. My code is this:

public void fade(object currentForm)
{
int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
currentForm.Opa city = i;
while(z<10000)
{
z++;
}
}
}

This works great if I go ahead and put it in my exit event on the form like
this:

int z = 0;
for(double i=1.0; i> 0; i-=.1)
{
this.Opacity = i;
while(z<10000)
{
z++;
}
}
this.Close();

When I have it in my helper Class Library it tells me that "'object' does
not contain a definition for 'Opacity'". Am I doing this wrong or is this not
allowed?

Thank you for your help!

[Marc Gravell]

Two observations:

1: any static method should probably be thread-aware; when dealing with
forms, this means that it should probably test currentForm.Inv okeRequired
and (if true) push the method onto the owning UI's thread; I'm pretty sure
(not 100%) that Opacity has thread affinity..

2: while(z<10000) {z++;}
I don't mean to be rude - just frank; this is quite possibly the worst way
of putting a delay into code:
* It will run at different speeds on different computers
* it might even get completely removed by an optimizing compiler (typically
only in release mode)
You don't want to Sleep(), as this will hang the UI thread (unless you spin
up a second thread that alternates between Sleep() [on its own thread] and
BeginInvoke() [on the form]); a timer would be the normal implementation?

Marc

[Marc Gravell]

2.1: plus it burns up CPU cycles for no good reason ;-p

[Chris Dunaway]

Bob Grommes wrote:

The type "object" does not have an opacity property, hence your error.
You would have to unbox the form instance you pass in -- a costly and
unnecessary step.

Correct me if I'm wrong, but boxing does not occur on references types.
Boxing refers to the conversion of a value type to a reference type
and unboxing is the conversion back. In this case, object is a
reference type already so no boxing occurs.

I took the OP code and ran it through Reflector and there are no box
instructions.