Should I instantiate the delegate or not?

[Carl Johansson]

Suppose I have a delegate variable, what is the difference between the
following two statements?

DelegateType methodPointer = new DelegateType(SomeMethod);

and...

DelegateType methodPointer = SomeMethod;

Both statements compile, and when the program runs I can't see any
difference in behavior? Is the constructor somehow automatically called in
the second case?

Regards Carl Johansson

 

[Graeme Bradbury]

It's VS2005 being smart for you.
If you were to look at the code through something like Reflector, you'd see
the created code is identical.

 

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

Carl,

In the second case, the compiler effectively creates the code that you
see in the first case. They do the same thing. C# 2.0 provided was when
the shorthand was introduced.

 

[Guest]

have alook on the ildasm code :

The first assignment

DelegateType methodPointer = new DelegateType(SomeMethod);
==========================================
..method public hidebysig instance void A() cil managed
{
// Code size 15 (0xf)
.maxstack 3
.locals init ([0] class CheckDelegate.Class1/DelegateType methodPointer)
IL_0000: nop
IL_0001: ldarg.0
IL_0002: ldftn instance void CheckDelegate.Class1::SomeMethod()
IL_0008: newobj instance void
CheckDelegate.Class1/DelegateType::.ctor(object,

native int)
IL_000d: stloc.0
IL_000e: ret
} // end of method Class1::A


The Second assignment :
..method public hidebysig instance void B() cil managed
{
// Code size 15 (0xf)
.maxstack 3
.locals init ([0] class CheckDelegate.Class1/DelegateType methodPointer)
IL_0000: nop
IL_0001: ldarg.0
IL_0002: ldftn instance void CheckDelegate.Class1::SomeMethod()
IL_0008: newobj instance void
CheckDelegate.Class1/DelegateType::.ctor(object,

native int)
IL_000d: stloc.0
IL_000e: ret
} // end of method Class1::B


As you can see the compiler do the same for both statements.

Conclusion :
They both are the same.

 

[Carl Johansson]

Thank you for your replies! Very helpful! I suppose with a tool to create
"ildasm code" I could have drawn this conclusion for myself. What is
"ildasm", "Intermediate Language DisASseMbler"? How can I get such a tool?

Regards Carl Johansson

have alook on the ildasm code :

The first assignment

DelegateType methodPointer = new DelegateType(SomeMethod);
==========================================
.method public hidebysig instance void A() cil managed
{
// Code size 15 (0xf)
.maxstack 3
.locals init ([0] class CheckDelegate.Class1/DelegateType methodPointer)
IL_0000: nop
IL_0001: ldarg.0
IL_0002: ldftn instance void CheckDelegate.Class1::SomeMethod()
IL_0008: newobj instance void
CheckDelegate.Class1/DelegateType::.ctor(object,

native int)
IL_000d: stloc.0
IL_000e: ret
} // end of method Class1::A


The Second assignment :
.method public hidebysig instance void B() cil managed
{
// Code size 15 (0xf)
.maxstack 3
.locals init ([0] class CheckDelegate.Class1/DelegateType methodPointer)
IL_0000: nop
IL_0001: ldarg.0
IL_0002: ldftn instance void CheckDelegate.Class1::SomeMethod()
IL_0008: newobj instance void
CheckDelegate.Class1/DelegateType::.ctor(object,

native int)
IL_000d: stloc.0
IL_000e: ret
} // end of method Class1::B


As you can see the compiler do the same for both statements.

Conclusion :
They both are the same.
--
Sincerely
Yaron Karni
http://dotnetbible.blogspot.com/

Suppose I have a delegate variable, what is the difference between the
following two statements?

DelegateType methodPointer = new DelegateType(SomeMethod);

and...

DelegateType methodPointer = SomeMethod;

Both statements compile, and when the program runs I can't see any
difference in behavior? Is the constructor somehow automatically called
in
the second case?

Regards Carl Johansson

 

[Jon Skeet [C# MVP]]

Thank you for your replies! Very helpful! I suppose with a tool to create
"ildasm code" I could have drawn this conclusion for myself. What is
"ildasm", "Intermediate Language DisASseMbler"? How can I get such a tool?

It's part of the SDK. If you have Visual Studio installed, just open a
Visual Studio Command Prompt and run "ildasm".

Alternatively, download Reflector which can show the IL or decompile to
C# (or VB.NET):
http://www.aisto.com/roeder/dotnet/