Library/boost/libs/python/doc/reference/enum.qbk - main - BirdLeon/ROBLOX2016

Library/boost/libs/python/doc/reference/enum.qbk
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19 дек 2024, 19:11
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[section boost/python/enum.hpp]
[section Introduction]
<boost/python/enum.hpp> defines the interface through which users expose their C++ enumeration types to Python. It declares the `enum_` class template, which is parameterized on the enumeration type being exposed.
[endsect]
[section Class template `enum_`]
Creates a Python class derived from Python's `int` type which is associated with the C++ type passed as its first parameter. 
``
namespace boost { namespace python
{
  template <class T>
  class enum_ : public object
  {
    enum_(char const* name, char const* doc = 0);
    enum_<T>& value(char const* name, T);
    enum_<T>& export_values();
  };
}}
``
[endsect]
[section Class template `enum_` constructors]
``enum_(char const* name, char const* doc=0);``
[variablelist
[[Requires][name is an [link ntbs] which conforms to Python's [@http://www.python.org/doc/current/ref/identifiers.html identifier naming rules].]]
[[Effects][Constructs an `enum_` object holding a Python extension type derived from `int` which is named `name`. The named attribute of the [link high_level_components.boost_python_scope_hpp current scope] is bound to the new extension type.]]
]
[endsect]
[section Class template `enum_` modifier functions]
``enum_<T>& value(char const* name, T x);``
[variablelist
[[Requires][name is an [link ntbs] which conforms to Python's [@http://www.python.org/doc/current/ref/identifiers.html identifier naming rules].]]
[[Effects][adds an instance of the wrapped enumeration type with value x to the type's dictionary as the named attribute.]]
[[Returns][`*this`]]
]
``enum_<T>& export_values();``
[variablelist
[[Effects][sets attributes in the [link high_level_components.boost_python_scope_hpp current scope] with the same names and values as all enumeration values exposed so far by calling value().]]
[[Returns][`*this`]]
]
[endsect]
[section Example]
C++ module definition
``
#include <boost/python/enum.hpp>
#include <boost/python/def.hpp>
#include <boost/python/module.hpp>

using namespace boost::python;

enum color { red = 1, green = 2, blue = 4 };

color identity_(color x) { return x; }

BOOST_PYTHON_MODULE(enums)
{
  enum_<color>("color")
    .value("red", red)
    .value("green", green)
    .export_values()
    .value("blue", blue)
    ;
  
  def("identity", identity_);
}
``
Interactive Python:
``
>>> from enums import *

>>> identity(red)
enums.color.red

>>> identity(color.red)
enums.color.red

>>> identity(green)
enums.color.green

>>> identity(color.green)
enums.color.green

>>> identity(blue)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'blue' is not defined

>>> identity(color.blue)
enums.color.blue

>>> identity(color(1))
enums.color.red

>>> identity(color(2))
enums.color.green

>>> identity(color(3))
enums.color(3)

>>> identity(color(4))
enums.color.blue

>>> identity(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: bad argument type for built-in operation
``
[endsect]
[endsect]