Comparing function pointers

[Mike Parker via Digitalmars-d-learn]

On 2/12/2015 3:40 AM, Freddy wrote:
> ----
> import std.stdio;
>
> auto test1(){
>      void testFunc(){
>      }
>      return &testFunc;
> }
>
> auto test2(){
>      uint a;
>      void testFunc(){
>          a=1;
>      }
>      return &testFunc;
> }
>
> void main(){
>      writeln(test1()==test1());//true
>      writeln(test2()==test2());//false
> }
> ----
> Is the intended behavior?

Read the section of the documentation about Delegates, Function 
Pointers, and Closures [1]. Neither of your pointers are actually 
function pointers. They are both delegates. The second one, as ketmar 
said, is a closure because it's a delegate with state. To get a function 
pointer from an inner function, the inner function must be static. 
Function pointers can't have state.

```
import std.stdio;

void printAnInt( int function() fptr ) {
     writeln( "From function pointer: ", fptr() );
}

void printAnInt( int delegate() dg ) {
     writeln( "From a delegate: ", dg() );
}

void main() {
     static int foo() { return 1; }
     int bar() { return 2; }

     printAnInt( &foo );
     printAnInt( &bar );
}
```

[1] http://dlang.org/function.html#closures