delegates and type safety !

[NotYetaNurd]

Hi all,

I read that delegates are type safe and Functional pointers are not!!...
in this context what does type safety mean?
can anyone of you throw some light on it

regards,
...

 

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

NetYetaNurd,

When it is said that delegates are type safe, consider the following:

public delegate void MyDelegate(int myParam);

This definition means that when I pass around a delegate, it MUST point
to a method that has the signature of one integer parameter, and no return
value. When using function pointers, it is just a pointer, and I can cast
it to anything, which could lead to problems if I cast it to the wrong
thing.

Hope this helps.

 

[NotYetaNurd]

Thanks Nicholas,
You are almost like my Online Tutor , Clearing Even my most silly doupts
with utmost clarity...

Thanks once again,
NetYetaNurd.

NetYetaNurd,

When it is said that delegates are type safe, consider the following:

public delegate void MyDelegate(int myParam);

This definition means that when I pass around a delegate, it MUST point
to a method that has the signature of one integer parameter, and no return
value. When using function pointers, it is just a pointer, and I can cast
it to anything, which could lead to problems if I cast it to the wrong
thing.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Hi all,

I read that delegates are type safe and Functional pointers are not!!...
in this context what does type safety mean?
can anyone of you throw some light on it

regards,
..

 

[Simon Trew]

Well yeah, if you *cast* it, but then that's true of many kinds of cast
operation in C/C++. It's not the fact that it's a function pointer that
makes it unsafe, but that a *cast* on it may be unsafe.

But function pointers are typed, just like any other pointers are typed. So
I don't know why this claim for delegates being typesafe is anything new.

S.

NetYetaNurd,

When it is said that delegates are type safe, consider the following:

public delegate void MyDelegate(int myParam);

This definition means that when I pass around a delegate, it MUST point
to a method that has the signature of one integer parameter, and no return
value. When using function pointers, it is just a pointer, and I can cast
it to anything, which could lead to problems if I cast it to the wrong
thing.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Hi all,

I read that delegates are type safe and Functional pointers are not!!...
in this context what does type safety mean?
can anyone of you throw some light on it

regards,
..

 

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

Simon,

Pointers in C++ are just integers that are a reference to a point in
memory which can be coerced into any other pointer type. This is not the
case in .NET. In .NET, references actually have a type associated with
them, and assignments to that are checked for validity (in other words, you
can not just cast around it).

Because of this, I could not take a delegate wrapping one method, and
coerce (cast) it into another delegate type with a different signature. I
could do this in C++ with function pointers (or cast any pointer to a
function pointer actually), often with unpredictable and undesirable
results.

I would argue that pointers in C++ are not type safe because you can
easily manipulate (cast) the pointer to any other pointer type. I would
even go further to say that there really is only one kind of pointer, that
the type doesn't really matter, because I can do this cast, effectively
rendering it useless.

--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Well yeah, if you *cast* it, but then that's true of many kinds of cast
operation in C/C++. It's not the fact that it's a function pointer that
makes it unsafe, but that a *cast* on it may be unsafe.

But function pointers are typed, just like any other pointers are typed. So
I don't know why this claim for delegates being typesafe is anything new.

S.

in message news:[email protected]...

NetYetaNurd,

When it is said that delegates are type safe, consider the following:

public delegate void MyDelegate(int myParam);

This definition means that when I pass around a delegate, it MUST point
to a method that has the signature of one integer parameter, and no return
value. When using function pointers, it is just a pointer, and I can cast
it to anything, which could lead to problems if I cast it to the wrong
thing.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Hi all,

I read that delegates are type safe and Functional pointers are not!!...
in this context what does type safety mean?
can anyone of you throw some light on it

regards,
..