Can we pass a method to another class?

[Tee]

Hi,

Can anyone tell me if it's possible to pass a method to another class?

Example of what I would like to do:

class1:

public void MyMethod()
{
code here
}

class2:

public void CallThisMethod(something MethodName)
{
MethodName();
}

Then I will call this code from class1:
class2.CallThisMethod(MyMethod)

So is this possible in .NET? if yes, can anyone give me a proper example?
Thanks alot,
Tee

[clu]

Sure you can.
The .NET way of doing this is by using delegates.
Delegates are the managed counterpart of the old-C function pointer ...
well, it's not exaclty a good sentence but I believe it makes thing
clearer !.

So what you have to do is:

1) Define a delegate. Delegates are types, the C# keyword "delegate" is
syntax sugar for defining your own type, inheriting from
MulticastDelegate and so on.

delegate void MyMethodDelegate();

--or--

delegate Boolean AnotherMethodWithArguments(Int32 i, ref String s, out
Object o);

2) Create an instance of the delegate type referring to your class1's
method

MyMethodDelegate d = new MyMethodDelegate(this.MyMethod);

3) Pass it to class2's method:

class2.CallThisMethod(d);

So your code will be re-written as follows:

class1:
// Nested inside class 1. This is just an option, it could be a
stand-alone type as well.
public delegate void MyMethodDelegate();

public void MyMethod()
{
code here

}
class2:

public void CallThisMethod(class1.MyMethodDelegate methodDelegate)
{
methodDelegate();
}
Then I will call this code from class1:
class2.CallThisMethod(new MyMethodDelegate(this.MyMethod));
Delegates offer much more than what I tried to explain in just a few
words, but this is more or less how they work !

For a good description about delegates, I suggest you to have a look at
the MSDN web site (msdn.microsoft.com) or at the excellent book by
Jeffrey Richter, Applied Microsoft .NET Framework Programming,
published by MSPress.

Best Regards.

Claudio Brotto
MCP, MCAD.NET

[clu]

Sure you can.
The .NET way of doing this is by using delegates.
Delegates are the managed counterpart of the old-C function pointer ...
well, it's not exaclty a good sentence but I believe it makes thing
clearer !.

So what you have to do is:

1) Define a delegate. Delegates are types, the C# keyword "delegate" is
syntax sugar for defining your own type, inheriting from
MulticastDelegate and so on.

delegate void MyMethodDelegate();

--or--

delegate Boolean AnotherMethodWithArguments(Int32 i, ref String s, out
Object o);

2) Create an instance of the delegate type referring to your class1's
method

MyMethodDelegate d = new MyMethodDelegate(this.MyMethod);

3) Pass it to class2's method:

class2.CallThisMethod(d);

So your code will be re-written as follows:

class1:
// Nested inside class 1. This is just an option, it could be a
stand-alone type as well.
public delegate void MyMethodDelegate();

public void MyMethod()
{
code here

}
class2:

public void CallThisMethod(class1.MyMethodDelegate methodDelegate)
{
methodDelegate();
}
Then I will call this code from class1:
class2.CallThisMethod(new MyMethodDelegate(this.MyMethod));
Delegates offer much more than what I tried to explain in just a few
words, but this is more or less how they work !

For a good description about delegates, I suggest you to have a look at
the MSDN web site (msdn.microsoft.com) or at the excellent book by
Jeffrey Richter, Applied Microsoft .NET Framework Programming,
published by MSPress.

Best Regards.

Claudio Brotto
MCP, MCAD.NET

[Chad Z. Hower aka Kudzu]

"Tee" <th*@streamyx.com> wrote in news:ev*************@TK2MSFTNGP15.phx.gbl:

Can anyone tell me if it's possible to pass a method to another class?

Yes. You need to create a delagate. See delegates in the C# help.
--
Chad Z. Hower (a.k.a. Kudzu) - http://www.hower.org/Kudzu/
"Programming is an art form that fights back"

Make your ASP.NET applications run faster
http://www.atozed.com/IntraWeb/

[Adam]

You can accomplish this using delegates. Declare the delegate with the
signature of the method that you'd like to pass around:

public delegate void MyMethodDelegate();

Then, write the actual method:

public void MyMethod() {
....code...
}

Then, you create an instance of the delegate:

MyMethodDelegate aDelegate = new MyMethodDelegate(MyMethod);

And the aDelegate object can be passed as a parameter:

Class2 class2Inst = new Class2();
class2Inst.CallThisMethod(aDelegate);

Where CallThisMethod is defined as:

public void CallThisMethod(MyMethodDelegate passedDelegate) {
passedDelegate();
}

Hope that helps.

Regards,

Adam

[Tee]

Thanks a lot, I will look into Delegate more.

"clu" <cl************@gmail.com> wrote in message
news:11*********************@z14g2000cwz.googlegro ups.com...

Sure you can.
The .NET way of doing this is by using delegates.
Delegates are the managed counterpart of the old-C function pointer ...
well, it's not exaclty a good sentence but I believe it makes thing
clearer !.

So what you have to do is:

1) Define a delegate. Delegates are types, the C# keyword "delegate" is
syntax sugar for defining your own type, inheriting from
MulticastDelegate and so on.

delegate void MyMethodDelegate();

--or--

delegate Boolean AnotherMethodWithArguments(Int32 i, ref String s, out
Object o);

2) Create an instance of the delegate type referring to your class1's
method

MyMethodDelegate d = new MyMethodDelegate(this.MyMethod);

3) Pass it to class2's method:

class2.CallThisMethod(d);

So your code will be re-written as follows:

class1:
// Nested inside class 1. This is just an option, it could be a
stand-alone type as well.
public delegate void MyMethodDelegate();

public void MyMethod()
{
code here

}
class2:

public void CallThisMethod(class1.MyMethodDelegate methodDelegate)
{
methodDelegate();
}
Then I will call this code from class1:
class2.CallThisMethod(new MyMethodDelegate(this.MyMethod));
Delegates offer much more than what I tried to explain in just a few
words, but this is more or less how they work !

For a good description about delegates, I suggest you to have a look at
the MSDN web site (msdn.microsoft.com) or at the excellent book by
Jeffrey Richter, Applied Microsoft .NET Framework Programming,
published by MSPress.

Best Regards.

Claudio Brotto
MCP, MCAD.NET

[Tim Jarvis]

Tee wrote:

Hi,

Can anyone tell me if it's possible to pass a method to another class?

Example of what I would like to do:

class1:

public void MyMethod()
{
code here
}

class2:

public void CallThisMethod(something MethodName)
{
MethodName();
}

Then I will call this code from class1:
class2.CallThisMethod(MyMethod)

So is this possible in .NET? if yes, can anyone give me a proper
example?
Thanks alot,
Tee

Hi Tee,

You have had some good and helpful advice in here re delegates, but I
just thought that I would also offer up something else as well....

in your example, if you are just wanting to call a method of a class,
and its always going to be that class (or a derivative of that class)
the simplest solution would be to simply pass an instance of the class
itself and just call the method i.e.

public class Class1
{
Public void MyMethod()
{
// Code here
}

}

public class Class2
{
public void CallThisMethod(Class1 class1Instance)
{
class1Instance.MyMethod();
}
}

Now this might not be what you are after, if you are just after the
ability to call a method of a particular signature and don't care about
the class hierarchy, but in your particular example above, this
(passing the class) would be the simplest solution.

Cheers Tim.