Doc/lib/libtypes.tex

   1 \section{\module{types} ---
   2          Names for built-in types}
   3
   4 \declaremodule{standard}{types}
   5 \modulesynopsis{Names for built-in types.}
   6
   7
   8 This module defines names for some object types that are used by
   9 the standard Python interpreter, but not for the types defined by various
  10 extension modules.  Also, it does not include some of the types that
  11 arise during processing such as the \code{listiterator} type.
  12 It is safe to use \samp{from types import *} ---
  13 the module does not export any names besides the ones listed here.
  14 New names exported by future versions of this module will all end in
  15 \samp{Type}.
  16
  17 Typical use is for functions that do different things depending on
  18 their argument types, like the following:
  19
  20 \begin{verbatim}
  21 from types import *
  22 def delete(mylist, item):
  23     if type(item) is IntType:
  24        del mylist[item]
  25     else:
  26        mylist.remove(item)
  27 \end{verbatim}
  28
  29 Starting in Python 2.2, built-in factory functions such as
  30 \function{int()} and \function{str()} are also names for the
  31 corresponding types.  This is now the preferred way to access
  32 the type instead of using the \module{types} module.  Accordingly,
  33 the example above should be written as follows:
  34
  35 \begin{verbatim}
  36 def delete(mylist, item):
  37     if isinstance(item, int):
  38        del mylist[item]
  39     else:
  40        mylist.remove(item)
  41 \end{verbatim}
  42
  43 The module defines the following names:
  44
  45 \begin{datadesc}{NoneType}
  46 The type of \code{None}.
  47 \end{datadesc}
  48
  49 \begin{datadesc}{TypeType}
  50 The type of type objects (such as returned by
  51 \function{type()}\bifuncindex{type}).
  52 \end{datadesc}
  53
  54 \begin{datadesc}{BooleanType}
  55 The type of the \class{bool} values \code{True} and \code{False}; this
  56 is an alias of the built-in \function{bool()} function.
  57 \versionadded{2.3}
  58 \end{datadesc}
  59
  60 \begin{datadesc}{IntType}
  61 The type of integers (e.g. \code{1}).
  62 \end{datadesc}
  63
  64 \begin{datadesc}{LongType}
  65 The type of long integers (e.g. \code{1L}).
  66 \end{datadesc}
  67
  68 \begin{datadesc}{FloatType}
  69 The type of floating point numbers (e.g. \code{1.0}).
  70 \end{datadesc}
  71
  72 \begin{datadesc}{ComplexType}
  73 The type of complex numbers (e.g. \code{1.0j}).  This is not defined
  74 if Python was built without complex number support.
  75 \end{datadesc}
  76
  77 \begin{datadesc}{StringType}
  78 The type of character strings (e.g. \code{'Spam'}).
  79 \end{datadesc}
  80
  81 \begin{datadesc}{UnicodeType}
  82 The type of Unicode character strings (e.g. \code{u'Spam'}).  This is
  83 not defined if Python was built without Unicode support.
  84 \end{datadesc}
  85
  86 \begin{datadesc}{TupleType}
  87 The type of tuples (e.g. \code{(1, 2, 3, 'Spam')}).
  88 \end{datadesc}
  89
  90 \begin{datadesc}{ListType}
  91 The type of lists (e.g. \code{[0, 1, 2, 3]}).
  92 \end{datadesc}
  93
  94 \begin{datadesc}{DictType}
  95 The type of dictionaries (e.g. \code{\{'Bacon': 1, 'Ham': 0\}}).
  96 \end{datadesc}
  97
  98 \begin{datadesc}{DictionaryType}
  99 An alternate name for \code{DictType}.
 100 \end{datadesc}
 101
 102 \begin{datadesc}{FunctionType}
 103 The type of user-defined functions and lambdas.
 104 \end{datadesc}
 105
 106 \begin{datadesc}{LambdaType}
 107 An alternate name for \code{FunctionType}.
 108 \end{datadesc}
 109
 110 \begin{datadesc}{GeneratorType}
 111 The type of generator-iterator objects, produced by calling a
 112 generator function.
 113 \versionadded{2.2}
 114 \end{datadesc}
 115
 116 \begin{datadesc}{CodeType}
 117 The type for code objects such as returned by
 118 \function{compile()}\bifuncindex{compile}.
 119 \end{datadesc}
 120
 121 \begin{datadesc}{ClassType}
 122 The type of user-defined classes.
 123 \end{datadesc}
 124
 125 \begin{datadesc}{InstanceType}
 126 The type of instances of user-defined classes.
 127 \end{datadesc}
 128
 129 \begin{datadesc}{MethodType}
 130 The type of methods of user-defined class instances.
 131 \end{datadesc}
 132
 133 \begin{datadesc}{UnboundMethodType}
 134 An alternate name for \code{MethodType}.
 135 \end{datadesc}
 136
 137 \begin{datadesc}{BuiltinFunctionType}
 138 The type of built-in functions like \function{len()} or
 139 \function{sys.exit()}.
 140 \end{datadesc}
 141
 142 \begin{datadesc}{BuiltinMethodType}
 143 An alternate name for \code{BuiltinFunction}.
 144 \end{datadesc}
 145
 146 \begin{datadesc}{ModuleType}
 147 The type of modules.
 148 \end{datadesc}
 149
 150 \begin{datadesc}{FileType}
 151 The type of open file objects such as \code{sys.stdout}.
 152 \end{datadesc}
 153
 154 \begin{datadesc}{XRangeType}
 155 The type of range objects returned by
 156 \function{xrange()}\bifuncindex{xrange}.
 157 \end{datadesc}
 158
 159 \begin{datadesc}{SliceType}
 160 The type of objects returned by
 161 \function{slice()}\bifuncindex{slice}.
 162 \end{datadesc}
 163
 164 \begin{datadesc}{EllipsisType}
 165 The type of \code{Ellipsis}.
 166 \end{datadesc}
 167
 168 \begin{datadesc}{TracebackType}
 169 The type of traceback objects such as found in
 170 \code{sys.exc_traceback}.
 171 \end{datadesc}
 172
 173 \begin{datadesc}{FrameType}
 174 The type of frame objects such as found in \code{tb.tb_frame} if
 175 \code{tb} is a traceback object.
 176 \end{datadesc}
 177
 178 \begin{datadesc}{BufferType}
 179 The type of buffer objects created by the
 180 \function{buffer()}\bifuncindex{buffer} function.
 181 \end{datadesc}
 182
 183 \begin{datadesc}{StringTypes}
 184 A sequence containing \code{StringType} and \code{UnicodeType} used to
 185 facilitate easier checking for any string object.  Using this is more
 186 portable than using a sequence of the two string types constructed
 187 elsewhere since it only contains \code{UnicodeType} if it has been
 188 built in the running version of Python.  For example:
 189 \code{isinstance(s, types.StringTypes)}.
 190 \versionadded{2.2}
 191 \end{datadesc}