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dft_tools/doc/reference/c++/clef/overload.rst
Olivier Parcollet 3fe400d34c doc : split c++ code from rst
- examples split from the rst file using a python script (split_code).
- Final result for the doc is unchanged.
- examples are compiled and tested with the other tests.
- examples' code have been clang-formatted, with triqs style.
- doc compiles much faster, and with the same options as the rest of the
  test.
- examples are added as tests, so they are run by make test, as simple C
  tests.
- done for the tutorials and the reference.
- autocompile removed (changed into triqs_example directive).
- add triqs_example :
   - make a literal include of the source code.
   - runs the compiled example
   - add, as before, the result to the source code in the doc.
- added the script split_code, used to make the changes automatically,
  maybe for later reuse. (in _tools)
2014-05-31 23:00:16 +02:00

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.. highlight:: c
Overloading functions and methods for CLEF arguments
=====================================================
.. _overload_function:
Overloading functions
----------------------------
Given a function, it is possible to overload it for CLEF expression arguments, returning a CLEF expression
using the `TRIQS_CLEF_MAKE_FNT_LAZY` macro.
**Synopsis** ::
namespace triqs { namespace clef {
TRIQS_CLEF_MAKE_FNT_LAZY (function_to_make_lazy);
}}
For example:
.. triqs_example:: ./overload_0.cpp
Note that :
* This overload **must** be defined in the triqs::clef namespace, since it is found by ADL.
* The function `foo` can have many overloads.
* The function `bar` can be a template, BUT then the template must be disabled for lazy expressions.
* The overload is already defined by clef for usual functions :
.. triqs_example:: ./overload_1.cpp
.. _callable_object:
Overloading operator() and other methods
---------------------------------------------------
Similarly to functions, classes can define an `operator()` for CLEF expressions arguments (or any other method).
It is an ordinary operator() that must :
* Be enabled only when one argument is a CLEF expression
* Return a CLEF expression.
Example :
.. triqs_example:: ./overload_2.cpp
**NB** When the method or the non CLEF operator() is already a template,
it must be disabled for clef expression argument, using the trait ::
clef::is_clef_expression<T...> // true iif one of the T is a clef expression
as the `bar` function above.