out parameters and contravariance

  • Thread starter Thread starter Marcel Müller
  • Start date Start date
M

Marcel Müller

Why does
public delegate void ActionOut<out T>(out T arg1);
not work?

From my understanding arg1 is only passed from the callee to the
caller, so it should be safe, if the delegate is invoked with a base
class of T.


Marcel
 
El martes, 16 de abril de 2013 14:04:17 UTC+2, Marcel Müller escribió:
Why does

public delegate void ActionOut<out T>(out T arg1);

not work?



From my understanding arg1 is only passed from the callee to the

caller, so it should be safe, if the delegate is invoked with a base

class of T.





Marcel
Click to expand...

Maybe a bit dumb question but... It looks like 'too generic to work'. Should not the T derive from EventArg?

Something like:

public delegate void ActionOut<T>(T arg1) where T : EventArgs
 
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