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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)
70 lines
1.9 KiB
ReStructuredText
70 lines
1.9 KiB
ReStructuredText
.. highlight:: c
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.. _clef_auto_assign:
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Automatic assignment of containers
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===================================
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Another use of expression is the automatic assignment of containers.
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**Synopsis**:
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If C is a container, ::
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C(x_) << some_expression_of_x_
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C[i_] << some_expression_of_i_
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C(x_)(i_,j_) << some_expression_of_x_i_j
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C[x_](i_,j_) << some_expression_of_x_i_j
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depending of course of the operator that the container support.
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The Right Hand Side (RHS) of the << statement can be any expression,
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while Left Hand Side (LHS) of the << sign is a container supporting the operation (see below).
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This statement simply will be rewritten by the CLEF library as ::
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triqs_clef_auto_assign (C, x_ -> some_expression_of_x_); // pseudo code
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triqs_clef_auto_assign (C, [](auto x_) {return some_expression_of_x_;}); // or in C++ lambda syntax
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The function `triqs_clef_auto_assign` has to be overloaded for the container and the correct
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functional form, and it is expected to fill C by evaluating this function.
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Such a function is provided for TRIQS objects (arrays, matrix, Green function),
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and also for some STL container like std::vector.
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Example :
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.. triqs_example:: ./assign_0.cpp
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**Details**
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The synopsis of the `triqs_clef_auto_assign` functions is ::
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template<typename Fnt> void triqs_clef_auto_assign (Obj & x, Fnt f);
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The compiler will then rewrite ::
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obj(x_,y_, ...) = expression
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into ::
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triqs_clef_auto_assign (obj, make_function( expression, x_, y_, ....))
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The function must be found by ADL. It is therefore useful to implement it e.g. as a friend function.
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Similarly, for [ ], adding a function ::
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template<typename Fnt> void triqs_clef_auto_assign_subscript (Obj & x, Fnt f);
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The compiler will rewrite ::
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obj[i_] = expression
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into ::
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triqs_clef_auto_assign_subscript (obj, make_function( expression, i_))
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A complete example:
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.. triqs_example:: ./assign_1.cpp
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