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digitalmars.D.learn - Two functions with different args. Taking address of the one

reply =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:
Have:
     void process( ref MouseKeyEvent event )
     {
        ...
     }

     void process( ref MouseMoveEvent event )
     {
        ...
     }

Want:
     _processMouseKey  = &process; // <-- not works
     _processMouseMove = &process; // <-- not works

What is correct way to get address of function with specific 
argument ?
Mar 11 2021
next sibling parent reply Paul Backus <snarwin gmail.com> writes:
On Thursday, 11 March 2021 at 12:26:07 UTC, Виталий Фадеев wrote:

 Have:
     void process( ref MouseKeyEvent event )
     {
        ...
     }

     void process( ref MouseMoveEvent event )
     {
        ...
     }

 Want:
     _processMouseKey  = &process; // <-- not works
     _processMouseMove = &process; // <-- not works

 What is correct way to get address of function with specific 
 argument ?


You can use __traits(getOverloads, process) plus some 
metaprogramming to get the address of a specific overload. But 
IMO the easiest way is to use lambdas:

     __processMouseKey = (ref MouseKeyEvent event) { 
process(event); };
     __processMouseMove = (ref MouseMoveEvent event) { 
process(event); };
Mar 11 2021
parent reply =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:
On Thursday, 11 March 2021 at 12:48:13 UTC, Paul Backus wrote:

 On Thursday, 11 March 2021 at 12:26:07 UTC, Виталий Фадеев 
 wrote:

 Have:
     void process( ref MouseKeyEvent event )
     {
        ...
     }

     void process( ref MouseMoveEvent event )
     {
        ...
     }

 Want:
     _processMouseKey  = &process; // <-- not works
     _processMouseMove = &process; // <-- not works

 What is correct way to get address of function with specific 
 argument ?


 You can use __traits(getOverloads, process) plus some 
 metaprogramming to get the address of a specific overload. But 
 IMO the easiest way is to use lambdas:

     __processMouseKey = (ref MouseKeyEvent event) { 
 process(event); };
     __processMouseMove = (ref MouseMoveEvent event) { 
 process(event); };


This will generate lambda:
   __processMouseKey = (ref MouseKeyEvent event) { process(event); 
};

two calls:
   call labnda;
     call process;

What right way to call function directly with selecting one of 
two ?
Mar 11 2021
next sibling parent reply Paul Backus <snarwin gmail.com> writes:
On Thursday, 11 March 2021 at 12:56:34 UTC, Виталий Фадеев wrote:

 This will generate lambda:
   __processMouseKey = (ref MouseKeyEvent event) { 
 process(event); };

 two calls:
   call labnda;
     call process;

 What right way to call function directly with selecting one of 
 two ?


Something like this:

     template Overloads(alias symbol)
     {
         static if (__traits(compiles, __traits(parent, symbol)))
             alias Overloads = __traits(getOverloads,
                 __traits(parent, symbol),
                 __traits(identifier, symbol)
             );
         else
             alias Overloads = symbol;
     }

     auto getOverloadFor(alias fun, T)()
     {
         foreach (overload; Overloads!fun)
             static if (__traits(compiles, (T arg) { 
overload(arg); }))
                 return &overload;
     }

Usage:

     __processMouseKey = getOverloadFor!(process, MouseKeyEvent);
Mar 11 2021
parent =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:
On Thursday, 11 March 2021 at 13:14:56 UTC, Paul Backus wrote:

 On Thursday, 11 March 2021 at 12:56:34 UTC, Виталий Фадеев 
 wrote:

 [...]


 Something like this:

     template Overloads(alias symbol)
     {
         static if (__traits(compiles, __traits(parent, symbol)))
             alias Overloads = __traits(getOverloads,
                 __traits(parent, symbol),
                 __traits(identifier, symbol)
             );
         else
             alias Overloads = symbol;
     }

     auto getOverloadFor(alias fun, T)()
     {
         foreach (overload; Overloads!fun)
             static if (__traits(compiles, (T arg) { 
 overload(arg); }))
                 return &overload;
     }

 Usage:

     __processMouseKey = getOverloadFor!(process, MouseKeyEvent);


Thanks a lot, bro!
Mar 11 2021
prev sibling parent Dennis <dkorpel gmail.com> writes:
On Thursday, 11 March 2021 at 12:56:34 UTC, Виталий Фадеев wrote:

 What right way to call function directly with selecting one of 
 two ?


If they are not nested functions, you can also do:
```
// Separate names
void processKey (ref MouseKeyEvent event) {...}
void processMove(ref MouseMoveEvent event) {...}

// Still create overload set
alias process = processKey;
alias process = processMove;

_processMouseKey  = &processKey;
_processMouseMove = &processMove;
```
Mar 11 2021
prev sibling parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Thursday, 11 March 2021 at 12:26:07 UTC, Виталий Фадеев wrote:

     _processMouseKey  = &process; // <-- not works
     _processMouseMove = &process; // <-- not works


This *should* actually work. What type are those variables?

struct MouseKeyEvent {}
struct MouseMoveEvent{}
void process( ref MouseKeyEvent event ) { }
void process( ref MouseMoveEvent event ) { }

void main() {
       // this works because the type is given on the left
       // so the compiler knows which overload works
         void function(ref MouseMoveEvent) processMouseMove = 
&process;
}
Mar 11 2021
parent =?UTF-8?B?0JLQuNGC0LDQu9C40Lkg0KTQsNC0?= =?UTF-8?B?0LXQtdCy?= writes:
On Thursday, 11 March 2021 at 14:23:39 UTC, Adam D. Ruppe wrote:

 On Thursday, 11 March 2021 at 12:26:07 UTC, Виталий Фадеев 
 wrote:

     _processMouseKey  = &process; // <-- not works
     _processMouseMove = &process; // <-- not works


 This *should* actually work. What type are those variables?

 struct MouseKeyEvent {}
 struct MouseMoveEvent{}
 void process( ref MouseKeyEvent event ) { }
 void process( ref MouseMoveEvent event ) { }

 void main() {
       // this works because the type is given on the left
       // so the compiler knows which overload works
         void function(ref MouseMoveEvent) processMouseMove = 
 &process;
 }


I was stupid.
It is really simple!

Thank a lot, bro!
Mar 11 2021