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digitalmars.D - IupSetCallback function passing

reply "James Wirth" <jwirth1 suddenlink.net> writes:
When trying to associate an Icallback function to a button in the 
IUP GUI
API using the IupSetCallback function, the D compiler seems to 
insist on evaluating that callback in order to pass its value 
rather than passing the function itself.

I get this dmd compiler error (the source is named hitmeiup.d) :

Error: function hitmeiup.hitMeAct (Ihandle_* dmy) is not callable 
using argument types ()
hitmeiup.d(41): Error: expected 1 function arguments, not 0

for this line calling the IupSetCallback:

	IupSetCallback(btn,"ACTION",hitMeAct);

The callback function was named hitMeAct as follows:

extern(C) {
	int hitMeAct(Ihandle *dmy) {
		sayHit();
		return 0;
	}
}

I have also tried it with hitMeAct being a D function instead of 
extern(C).

It is as if the	call to IupSetCallback is interpreting hitMeAct 
to be a property function and that the call was meant to be:

	IupSetCallback(btn,"ACTION",hitMeAct());

It there someway to force D to consider the hitMeAct parameter to 
be passing a function and NOT calling it?  I tried prefixing a & 
- no go.

Would welcome any hints.

Yes I have already looked at the .d files purporting to provide 
access to IUP.
And a more or less equivalent C program works fine.
Mar 18 2014
next sibling parent "Infiltrator" <Lt.Infiltrator gmail.com> writes:
On Wednesday, 19 March 2014 at 02:21:18 UTC, James Wirth wrote:
 When trying to associate an Icallback function to a button in 
 the IUP GUI
 API using the IupSetCallback function, the D compiler seems to 
 insist on evaluating that callback in order to pass its value 
 rather than passing the function itself.

 I get this dmd compiler error (the source is named hitmeiup.d) :

 Error: function hitmeiup.hitMeAct (Ihandle_* dmy) is not 
 callable using argument types ()
 hitmeiup.d(41): Error: expected 1 function arguments, not 0

 for this line calling the IupSetCallback:

 	IupSetCallback(btn,"ACTION",hitMeAct);

 The callback function was named hitMeAct as follows:

 extern(C) {
 	int hitMeAct(Ihandle *dmy) {
 		sayHit();
 		return 0;
 	}
 }

 I have also tried it with hitMeAct being a D function instead 
 of extern(C).

 It is as if the	call to IupSetCallback is interpreting hitMeAct 
 to be a property function and that the call was meant to be:

 	IupSetCallback(btn,"ACTION",hitMeAct());

 It there someway to force D to consider the hitMeAct parameter 
 to be passing a function and NOT calling it?  I tried prefixing 
 a & - no go.

 Would welcome any hints.

 Yes I have already looked at the .d files purporting to provide 
 access to IUP.
 And a more or less equivalent C program works fine.

Why is it that prefixing it with '&' does not work? Am I safe in assuming that it then complains about hitMeAct being not callable with parameters ()? In which case, try currying it: import std.functional : curry; IupSetCallback(btn, "ACTION", &curry!(hitMeAct, dmy));
Mar 18 2014
prev sibling parent "Rikki Cattermole" <alphaglosined gmail.com> writes:
On Wednesday, 19 March 2014 at 02:21:18 UTC, James Wirth wrote:
 When trying to associate an Icallback function to a button in 
 the IUP GUI
 API using the IupSetCallback function, the D compiler seems to 
 insist on evaluating that callback in order to pass its value 
 rather than passing the function itself.

 I get this dmd compiler error (the source is named hitmeiup.d) :

 Error: function hitmeiup.hitMeAct (Ihandle_* dmy) is not 
 callable using argument types ()
 hitmeiup.d(41): Error: expected 1 function arguments, not 0

 for this line calling the IupSetCallback:

 	IupSetCallback(btn,"ACTION",hitMeAct);

 The callback function was named hitMeAct as follows:

 extern(C) {
 	int hitMeAct(Ihandle *dmy) {
 		sayHit();
 		return 0;
 	}
 }

 I have also tried it with hitMeAct being a D function instead 
 of extern(C).

 It is as if the	call to IupSetCallback is interpreting hitMeAct 
 to be a property function and that the call was meant to be:

 	IupSetCallback(btn,"ACTION",hitMeAct());

 It there someway to force D to consider the hitMeAct parameter 
 to be passing a function and NOT calling it?  I tried prefixing 
 a & - no go.

 Would welcome any hints.

 Yes I have already looked at the .d files purporting to provide 
 access to IUP.
 And a more or less equivalent C program works fine.

Using & to get the function pointer is correct in this case. You may need to do a cast for the pointer to what c expects. However it will work fine. The brackets forces it to call it. Don't.
Mar 18 2014