//DMD64 D Compiler 2.072.2
import std.stdio;

bool foo(  bool function( double ) controlFoo )
{
    return controlFoo(5.0);
}

void foo2( double val )
{
    writeln  ( foo( a => a > val ) );
}

void main()
{
    foo2(20);
    writeln("Hello, World!");
}

Does not compile and gives this errors:
source_file.d(12): Error: function source.foo2.__lambda2 cannot access frame of function source.foo2
source_file.d(12): Error: function source.foo (bool function(double) controlFoo) is not callable using argument types (void)

Live example:
http://rextester.com/WRKCWR55408

Is there any workaround for that?

Regards
Erdem

On Saturday, 18 November 2017 at 14:22:19 UTC, kerdemdemir wrote:
> bool foo(  bool function( double ) controlFoo )

Change that `function` to `delegate` and it should work.

Function pointers aren't allowed to access other locals, but delegates are.

On Saturday, 18 November 2017 at 14:30:29 UTC, Adam D. Ruppe wrote:
> On Saturday, 18 November 2017 at 14:22:19 UTC, kerdemdemir wrote:
>> bool foo(  bool function( double ) controlFoo )
>
> Change that `function` to `delegate` and it should work.
>
> Function pointers aren't allowed to access other locals, but delegates are.

Yes it worked as you suggested.

Thanks.

On 11/18/2017 06:22 AM, kerdemdemir wrote:
> //DMD64 D Compiler 2.072.2
> import std.stdio;
> 
> bool foo(  bool function( double ) controlFoo )
> {
>      return controlFoo(5.0);
> }
> 
> void foo2( double val )
> {
>      writeln  ( foo( a => a > val ) );
> }
> 
> void main()
> {
>      foo2(20);
>      writeln("Hello, World!");
> }
> 
> Does not compile and gives this errors:
> source_file.d(12): Error: function source.foo2.__lambda2 cannot access frame of function source.foo2

foo should take 'delegate'.

If you want it to work with any callable entity, take the function as an alias template parameter:

bool foo(alias controlFoo)()
{
    return controlFoo(5.0);
}

void foo2( double val )
{
    writeln  ( foo!( a => a > val )() );
}

Ali