doc/named-param.dox
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     1 /* -*- C++ -*-
     1 /* -*- mode: C++; indent-tabs-mode: nil; -*-
     2  *
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library
     3  * This file is a part of LEMON, a generic C++ optimization library.
     4  *
     4  *
     5  * Copyright (C) 2003-2008
     5  * Copyright (C) 2003-2008
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     8  *
    23 \section named-func-param Named Function Parameters
    23 \section named-func-param Named Function Parameters
    24
    24
    25 Several modern languages provide a convenient way to refer the
    25 Several modern languages provide a convenient way to refer the
    26 function parameters by name also when you call the function. It is
    26 function parameters by name also when you call the function. It is
    27 especially comfortable in case of a function having tons of parameters
    27 especially comfortable in case of a function having tons of parameters
    28 with natural default values. Sadly, C++ lack this amenity.
    28 with natural default values. Sadly, C++ lack this amenity.
    29
    29
    30 However, with a crafty trick and with some little
    30 However, with a crafty trick and with some little
    31 inconvenience, it is possible to emulate is.
    31 inconvenience, it is possible to emulate is.
    32 The example below shows how to do it.
    32 The example below shows how to do it.
    33
    33
    34 \code
    34 \code
    35 class namedFn
    35 class namedFn
    36 {
    36 {
    37   int _id;
    37   int _id;
    38   double _val;
    38   double _val;
    39   int _dim;
    39   int _dim;
    40
    40
    41   public:
    41   public:
    42   namedFn() : _id(0), _val(1), _dim(2) {}
    42   namedFn() : _id(0), _val(1), _dim(2) {}
    43   namedFn& id(int p)     { _id  = p ; return *this; }
    43   namedFn& id(int p)     { _id  = p ; return *this; }
    44   namedFn& val(double p) { _val = p ; return *this; }
    44   namedFn& val(double p) { _val = p ; return *this; }
    45   namedFn& dim(int p)    { _dim = p ; return *this; }
    45   namedFn& dim(int p)    { _dim = p ; return *this; }
    46
    46
    47   run() {
    47   run() {
    48   std::cout << "Here comes the function itself\n" <<
    48     std::cout << "Here comes the function itself\n" <<
    49             << "With parameters "
    49               << "With parameters "
    50             << _id << ", " << _val << ", " << _dim << std::endl;
    50               << _id << ", " << _val << ", " << _dim << std::endl;
    51   }
    51   }
    52 };
    52 };
    53 \endcode
    53 \endcode
    54
    54
    55 Then you can use it like this.
    55 Then you can use it like this.
    74 explicitly to execute a function having named parameters
    74 explicitly to execute a function having named parameters
    75 everywhere in LEMON.</b>
    75 everywhere in LEMON.</b>
    76
    76
    77 \section named-templ-func-param Named Function Template Parameters
    77 \section named-templ-func-param Named Function Template Parameters
    78
    78
    79 A named parameter can also be a template functions. The usage is
    79 A named parameter can also be a template function. The usage is
    80 exactly the same, but the implementation behind is a kind of black
    80 exactly the same, but the implementation behind is a kind of black
    81 magic and they are the dirtiest part of the LEMON code.
    81 magic and they are the dirtiest part of the LEMON code.
    82
    82
    83 You will probably never need to know how it works, but if you really
    83 You will probably never need to know how it works, but if you really
    84 committed, have a look at \ref lemon/graph_to_eps.h for an example.
    84 committed, have a look at \ref lemon/graph_to_eps.h for an example.
   101 the class contains named parameters, we do not have to instantiate again
   101 the class contains named parameters, we do not have to instantiate again
   102 the class with new traits class, but instead adaptor classes can
   102 the class with new traits class, but instead adaptor classes can
   103 be used as shown in the following example.
   103 be used as shown in the following example.
   104
   104
   105 \code
   105 \code
   106 Dijkstra<>::SetPredNodeMap<NullMap<Node,Node> >::Create
   106 Dijkstra<>::SetPredMap<NullMap<Node,Arc> >::Create
   107 \endcode
   107 \endcode
   108
   108
   109 It can also be used in conjunction with other named template
   109 It can also be used in conjunction with other named template
   110 parameters in arbitrary order.
   110 parameters in arbitrary order.
   111
   111
   112 \code
   112 \code
   113 Dijkstra<>::SetDistMap<MyMap>::SetPredMap<NullMap<Node,Edge> >::Create
   113 Dijkstra<>::SetDistMap<MyMap>::SetPredMap<NullMap<Node,Arc> >::Create
   114 \endcode
   114 \endcode
   115
   115
   116 The result will be an instantiated Dijkstra class, in which the
   116 The result will be an instantiated Dijkstra class, in which the
   117 DistMap and the PredMap is modified.
   117 DistMap and the PredMap is modified.
   118
   118