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digitalmars.D.learn - Writing UFCS function for any instance of a templated struct

reply "Rene Zwanenburg" <renezwanenburg gmail.com> writes:
Hi,

I'd like to write a function for a vector template which 
basically looks like

struct Vec(T, size_t size) {
   T[size] e;
}

This template has a few properties with very common names like x, 
y, z, etc. To avoid mistakes I'd like to write a template 
constraint for UFCS functions so it accepts any instance of the 
Vec template, but nothing else. Something in the gist of

auto innerProduct(T)(const T v1, const T v2) if(is(T == Vec)) {

}

How can I do this?
Sep 13 2012
next sibling parent David <d dav1d.de> writes:
Am 13.09.2012 11:46, schrieb Rene Zwanenburg:

 Hi,

 I'd like to write a function for a vector template which basically looks
 like

 struct Vec(T, size_t size) {
    T[size] e;
 }

 This template has a few properties with very common names like x, y, z,
 etc. To avoid mistakes I'd like to write a template constraint for UFCS
 functions so it accepts any instance of the Vec template, but nothing
 else. Something in the gist of

 auto innerProduct(T)(const T v1, const T v2) if(is(T == Vec)) {

 }

 How can I do this?



I am doing it in gl3n like this: 
https://github.com/Dav1dde/gl3n/blob/master/gl3n/util.d#L15

(Sorry when I just sent you a private e-mail, I clicked the wrong answer 
button in thunderbird)
Sep 13 2012
prev sibling next sibling parent "Rene Zwanenburg" <renezwanenburg gmail.com> writes:
That works, nice trick!

Thanks

On Thursday, 13 September 2012 at 10:09:08 UTC, David wrote:

 Am 13.09.2012 11:46, schrieb Rene Zwanenburg:

 Hi,

 I'd like to write a function for a vector template which 
 basically looks
 like

 struct Vec(T, size_t size) {
   T[size] e;
 }

 This template has a few properties with very common names like 
 x, y, z,
 etc. To avoid mistakes I'd like to write a template constraint 
 for UFCS
 functions so it accepts any instance of the Vec template, but 
 nothing
 else. Something in the gist of

 auto innerProduct(T)(const T v1, const T v2) if(is(T == Vec)) {

 }

 How can I do this?



 I am doing it in gl3n like this: 
 https://github.com/Dav1dde/gl3n/blob/master/gl3n/util.d#L15

 (Sorry when I just sent you a private e-mail, I clicked the 
 wrong answer button in thunderbird)
Sep 13 2012
prev sibling next sibling parent "bearophile" <bearophileHUGS lycos.com> writes:
Rene Zwanenburg:


 How can I do this?



One possible solution:


struct Vec(T, size_t size) {
     T[size] e;
}
void innerProduct(T, size_t n)(const Vec!(T, n) v1,
                                const Vec!(T, n) v2) {}
void main() {
     Vec!(int, 3) v1, v2;
     innerProduct(v1, v2);
}


(While writing it I have found another little compiler bug).

Bye,
bearophile
Sep 13 2012
prev sibling parent "Rene Zwanenburg" <renezwanenburg gmail.com> writes:
That's actually quite straightforward. I forgot how well D's type 
deduction works.

Thanks

On Thursday, 13 September 2012 at 11:01:18 UTC, bearophile wrote:

 Rene Zwanenburg:


 How can I do this?



 One possible solution:


 struct Vec(T, size_t size) {
     T[size] e;
 }
 void innerProduct(T, size_t n)(const Vec!(T, n) v1,
                                const Vec!(T, n) v2) {}
 void main() {
     Vec!(int, 3) v1, v2;
     innerProduct(v1, v2);
 }


 (While writing it I have found another little compiler bug).

 Bye,
 bearophile
Sep 13 2012