How to test if a delegate or event is empty

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RFOG - 13 Oct 2006 12:31 GMT

In C# is very easy:

if(myDelegate==null)
//Install it.

but in C++/CLI that does not work:

if(myDelegate==nullptr)
//Install it.

gives:

Error C3918:usage requires 'member' to be a data member

But myDelegate has operator == overloaded. I don't understand why it fails.
If I try some like this:

myDelegate->GetInvocationList()->Length==0

I get same error.

And other variations.

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Ben Voigt - 07 Nov 2006 20:55 GMT

> In C# is very easy:
>
[quoted text clipped - 9 lines]
>
> Error C3918:usage requires 'member' to be a data member

Use a custom event, like this:

private:

//! \brief MulticastDelegate chain of event handlers for the \ref Closed
event.

System::EventHandler^ CloseHandlers;

public:

virtual event System::EventHandler^ Closed

{

void add( System::EventHandler^ handler )

{

CloseHandlers += handler;

}

void remove( System::EventHandler^ handler )

{

CloseHandlers += handler;

}

}

> But myDelegate has operator == overloaded. I don't understand why it
> fails.
[quoted text clipped - 5 lines]
>
> And other variations.

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How to test if a delegate or event is empty

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