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dft_tools/doc/reference/clef/overload.rst
tayral edd1ff4529 Restructuring documentation.
A first general restructuration of the doc according to the pattern [tour|tutorial|reference].
In the reference part, objects are documented per topic.
In each topic, [definition|c++|python|hdf5] (not yet implemented)
2014-10-18 12:21:08 +01:00

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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.