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digitalmars.D - Compile-time reflection and templates

reply Jean-Louis Leroy <jl leroy.nyc> writes:
I can identify the templates in a module:

   module modtemp;

   import std.stdio;
   import std.traits;

   void foo(T)(T x) {}

   void main()
   {
     foreach (m; __traits(allMembers, modtemp)) {
       if (__traits(isTemplate, mixin(m))) {
         mixin("alias F = " ~ m ~ ";");
         writeln(m);
       }
     }
   }
   // output:
   // foo

I'd like to go further: find the template arguments and the 
function arguments and return types. Looking at __traits and 
std.traits, it doesn't seem feasible, but maybe I overlooked 
something?
Sep 27 2017
next sibling parent jmh530 <john.michael.hall gmail.com> writes:
On Wednesday, 27 September 2017 at 19:47:32 UTC, Jean-Louis Leroy 
wrote:

 I'd like to go further: find the template arguments and the 
 function arguments and return types. Looking at __traits and 
 std.traits, it doesn't seem feasible, but maybe I overlooked 
 something?


You can use TemplateArgsOf
https://dlang.org/phobos/std_traits.html#TemplateArgsOf
to get the template arguments.

You can test if it's a function
https://dlang.org/phobos/std_traits.html#isFunction

You can get the Parameter and Return types
https://dlang.org/phobos/std_traits.html#Parameters
https://dlang.org/phobos/std_traits.html#ReturnType

You can get the names of parameters
https://dlang.org/phobos/std_traits.html#ParameterIdentifierTuple
Sep 27 2017
prev sibling next sibling parent reply jmh530 <john.michael.hall gmail.com> writes:
On Wednesday, 27 September 2017 at 19:47:32 UTC, Jean-Louis Leroy 
wrote:

 I'd like to go further: find the template arguments and the 
 function arguments and return types. Looking at __traits and 
 std.traits, it doesn't seem feasible, but maybe I overlooked 
 something?


You can use TemplateArgsOf
https://dlang.org/phobos/std_traits.html#TemplateArgsOf
to get the template arguments.

For the stuff below, I think you can't just use foo, it has to be 
a specific foo!T.

You can test if it's a function
https://dlang.org/phobos/std_traits.html#isFunction

You can get the Parameter and Return types
https://dlang.org/phobos/std_traits.html#Parameters
https://dlang.org/phobos/std_traits.html#ReturnType

You can get the names of parameters
https://dlang.org/phobos/std_traits.html#ParameterIdentifierTuple
Sep 27 2017
parent reply Jean-Louis Leroy <jl leroy.nyc> writes:
On Wednesday, 27 September 2017 at 20:04:42 UTC, jmh530 wrote:

 On Wednesday, 27 September 2017 at 19:47:32 UTC, Jean-Louis 
 Leroy wrote:

 I'd like to go further: find the template arguments and the 
 function arguments and return types. Looking at __traits and 
 std.traits, it doesn't seem feasible, but maybe I overlooked 
 something?


 You can use TemplateArgsOf
 https://dlang.org/phobos/std_traits.html#TemplateArgsOf
 to get the template arguments.

 For the stuff below, I think you can't just use foo, it has to 
 be a specific foo!T.

 You can test if it's a function
 https://dlang.org/phobos/std_traits.html#isFunction

 You can get the Parameter and Return types
 https://dlang.org/phobos/std_traits.html#Parameters
 https://dlang.org/phobos/std_traits.html#ReturnType

 You can get the names of parameters
 https://dlang.org/phobos/std_traits.html#ParameterIdentifierTuple


I am aware of these but TemplateArgsOf takes a template 
*instantiation* and returns the arguments. I want to reflect the 
*template*.

Here what I am trying to achieve (for openmethods). Given:

   Matrix!T times(T, virtual!(Matrix!T));

...inject, at compile time (in 'mixin(registerMethods)'), the 
following code:

   Matrix!T times(T)(T s, Matrix!T m) {
     return Method!("times", "deallocator", Matrix!T, T, 
virtual!(Matrix!T)).dispatcher(s, m);
   }

   Method!("times", "deallocator", Matrix!T, T, 
virtual!(Matrix!T)) times(T)(MethodTag, T s, Matrix!T m);
Sep 27 2017
parent jmh530 <john.michael.hall gmail.com> writes:
On Wednesday, 27 September 2017 at 21:18:54 UTC, Jean-Louis Leroy 
wrote:

 I am aware of these but TemplateArgsOf takes a template 
 *instantiation* and returns the arguments. I want to reflect 
 the *template*.


Yeah, I had kind of realized the point about instantiate mid-post.
Sep 27 2017
prev sibling parent Jacob Carlborg <doob me.com> writes:
On 2017-09-27 21:47, Jean-Louis Leroy wrote:


 I'd like to go further: find the template arguments 


There was a pull request that implemented this [1]. But it was closed, 
added to many new traits.

[1] https://github.com/dlang/dmd/pull/5201

-- 
/Jacob Carlborg
Sep 28 2017