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digitalmars.D.learn - How to determine if a function is implemented

reply "JS" <js.mdnq gmail.com> writes:
the code

http://dpaste.dzfl.pl/25bfeeb7

attempts to implement an interface. The current issue is that I 
need to determine if the user has added the member of the 
interface to the class or if the mixin needs to add it.


so the lines

class B : A
{
	A a;
	
	//void myfunc(float a, int b, string c) { };
	// property int myvalue() { return 4; }
	mixin implementInterface!a;
}

The mixin adds the two commented functions above it which 
effectively implement the interface A in B. The problem is, I 
might want to manually specify one, e.g.,


class B : A
{
	A a;
	
	void myfunc(float a, int b, string c) { };
	// property int myvalue() { return 4; }
	mixin implementInterface!a;
}

So the mixin needs to be aware and not add a method that is 
already implemented.
I need some way for the mixin to distinguish the two cases above. 
e.g., isImplemented!(myfunc(float, int, string)) or something 
like that.
Jul 04 2013
parent reply "Kenji Hara" <k.hara.pg gmail.com> writes:
On Friday, 5 July 2013 at 01:27:06 UTC, JS wrote:

 the code

 http://dpaste.dzfl.pl/25bfeeb7

 attempts to implement an interface. The current issue is that I 
 need to determine if the user has added the member of the 
 interface to the class or if the mixin needs to add it.


 so the lines

 class B : A
 {
 	A a;
 	
 	//void myfunc(float a, int b, string c) { };
 	// property int myvalue() { return 4; }
 	mixin implementInterface!a;
 }

 The mixin adds the two commented functions above it which 
 effectively implement the interface A in B. The problem is, I 
 might want to manually specify one, e.g.,


 class B : A
 {
 	A a;
 	
 	void myfunc(float a, int b, string c) { };
 	// property int myvalue() { return 4; }
 	mixin implementInterface!a;
 }

 So the mixin needs to be aware and not add a method that is 
 already implemented.
 I need some way for the mixin to distinguish the two cases 
 above. e.g., isImplemented!(myfunc(float, int, string)) or 
 something like that.


It's completely unnecessary. A mixed-in function cannot override 
properly declared function that has same name in the mixed-in 
scope.


interface I { int foo(); }

mixin template Foo()
{
     override int foo() { return 1; }
}

class C1 : I {
     mixin Foo!();
}

class C2 : I
{
     int foo() { return 10; }
     mixin Foo!();
     // mixed-in foo is not stored in vtbl
}

void main()
{
     assert(new C1().foo() == 1);
     assert(new C2().foo() == 10);
}

Kenji Hara
Jul 04 2013
next sibling parent "Michael" <pr m1xa.com> writes:
 class C2 : I
 {
     int foo() { return 10; }
     mixin Foo!();
     // mixed-in foo is not stored in vtbl
 }


In this case maybe should be error thrown?
Or where is mixed function?
Jul 05 2013
prev sibling parent "JS" <js.mdnq gmail.com> writes:
On Friday, 5 July 2013 at 06:34:58 UTC, Kenji Hara wrote:

 On Friday, 5 July 2013 at 01:27:06 UTC, JS wrote:

 the code

 http://dpaste.dzfl.pl/25bfeeb7

 attempts to implement an interface. The current issue is that 
 I need to determine if the user has added the member of the 
 interface to the class or if the mixin needs to add it.


 so the lines

 class B : A
 {
 	A a;
 	
 	//void myfunc(float a, int b, string c) { };
 	// property int myvalue() { return 4; }
 	mixin implementInterface!a;
 }

 The mixin adds the two commented functions above it which 
 effectively implement the interface A in B. The problem is, I 
 might want to manually specify one, e.g.,


 class B : A
 {
 	A a;
 	
 	void myfunc(float a, int b, string c) { };
 	// property int myvalue() { return 4; }
 	mixin implementInterface!a;
 }

 So the mixin needs to be aware and not add a method that is 
 already implemented.
 I need some way for the mixin to distinguish the two cases 
 above. e.g., isImplemented!(myfunc(float, int, string)) or 
 something like that.


 It's completely unnecessary. A mixed-in function cannot 
 override properly declared function that has same name in the 
 mixed-in scope.


 interface I { int foo(); }

 mixin template Foo()
 {
     override int foo() { return 1; }
 }

 class C1 : I {
     mixin Foo!();
 }

 class C2 : I
 {
     int foo() { return 10; }
     mixin Foo!();
     // mixed-in foo is not stored in vtbl
 }

 void main()
 {
     assert(new C1().foo() == 1);
     assert(new C2().foo() == 10);
 }

 Kenji Hara


Cool, now that you've pointed that out I do remember reading 
that. The code was working all along, the issue being d-ide 
saying that build failed and not producing a binary. I guess this 
solves that problem and I better implement the code.
Jul 05 2013