Doc/lib/liboperator.tex

   1 \section{\module{operator} ---
   2          Standard operators as functions.}
   3 \declaremodule{builtin}{operator}
   4 \sectionauthor{Skip Montanaro}{skip@automatrix.com}
   5
   6 \modulesynopsis{All Python's standard operators as built-in functions.}
   7
   8
   9 The \module{operator} module exports a set of functions implemented in C
  10 corresponding to the intrinsic operators of Python.  For example,
  11 \code{operator.add(x, y)} is equivalent to the expression \code{x+y}.  The
  12 function names are those used for special class methods; variants without
  13 leading and trailing \samp{__} are also provided for convenience.
  14
  15 The \module{operator} module defines the following functions:
  16
  17 \begin{funcdesc}{add}{a, b}
  18 \funcline{__add__}{a, b}
  19 Return \var{a} \code{+} \var{b}, for \var{a} and \var{b} numbers.
  20 \end{funcdesc}
  21
  22 \begin{funcdesc}{sub}{a, b}
  23 \funcline{__sub__}{a, b}
  24 Return \var{a} \code{-} \var{b}.
  25 \end{funcdesc}
  26
  27 \begin{funcdesc}{mul}{a, b}
  28 \funcline{__mul__}{a, b}
  29 Return \var{a} \code{*} \var{b}, for \var{a} and \var{b} numbers.
  30 \end{funcdesc}
  31
  32 \begin{funcdesc}{div}{a, b}
  33 \funcline{__div__}{a, b}
  34 Return \var{a} \code{/} \var{b}.
  35 \end{funcdesc}
  36
  37 \begin{funcdesc}{mod}{a, b}
  38 \funcline{__mod__}{a, b}
  39 Return \var{a} \code{\%} \var{b}.
  40 \end{funcdesc}
  41
  42 \begin{funcdesc}{neg}{o}
  43 \funcline{__neg__}{o}
  44 Return \var{o} negated.
  45 \end{funcdesc}
  46
  47 \begin{funcdesc}{pos}{o}
  48 \funcline{__pos__}{o}
  49 Return \var{o} positive.
  50 \end{funcdesc}
  51
  52 \begin{funcdesc}{abs}{o}
  53 \funcline{__abs__}{o}
  54 Return the absolute value of \var{o}.
  55 \end{funcdesc}
  56
  57 \begin{funcdesc}{inv}{o}
  58 \funcline{__inv__}{o}
  59 Return the inverse of \var{o}.
  60 \end{funcdesc}
  61
  62 \begin{funcdesc}{lshift}{a, b}
  63 \funcline{__lshift__}{a, b}
  64 Return \var{a} shifted left by \var{b}.
  65 \end{funcdesc}
  66
  67 \begin{funcdesc}{rshift}{a, b}
  68 \funcline{__rshift__}{a, b}
  69 Return \var{a} shifted right by \var{b}.
  70 \end{funcdesc}
  71
  72 \begin{funcdesc}{and_}{a, b}
  73 \funcline{__and__}{a, b}
  74 Return the bitwise and of \var{a} and \var{b}.
  75 \end{funcdesc}
  76
  77 \begin{funcdesc}{or_}{a, b}
  78 \funcline{__or__}{a, b}
  79 Return the bitwise or of \var{a} and \var{b}.
  80 \end{funcdesc}
  81
  82 \begin{funcdesc}{xor}{a, b}
  83 \funcline{__xor__}{a, b}
  84 Return the bitwise exclusive or of \var{a} and \var{b}.
  85 \end{funcdesc}
  86
  87 \begin{funcdesc}{not_}{o}
  88 \funcline{__not__}{o}
  89 Return the outcome of \keyword{not} \var{o}.  (Note that there is no
  90 \method{__not__()} discipline for object instances; only the
  91 interpreter core defines this operation.)
  92 \end{funcdesc}
  93
  94 \begin{funcdesc}{truth}{o}
  95 Return \code{1} if \var{o} is true, and 0 otherwise.
  96 \end{funcdesc}
  97
  98 \begin{funcdesc}{concat}{a, b}
  99 \funcline{__concat__}{a, b}
 100 Return \var{a} \code{+} \var{b} for \var{a} and \var{b} sequences.
 101 \end{funcdesc}
 102
 103 \begin{funcdesc}{repeat}{a, b}
 104 \funcline{__repeat__}{a, b}
 105 Return \var{a} \code{*} \var{b} where \var{a} is a sequence and
 106 \var{b} is an integer.
 107 \end{funcdesc}
 108
 109 \begin{funcdesc}{contains}{a, b}
 110 \funcline{sequenceIncludes}{a, b}
 111 Return the outcome of the test \var{b} \code{in} \var{a}.
 112 Note the reversed operands.
 113 \end{funcdesc}
 114
 115 \begin{funcdesc}{countOf}{a, b}
 116 Return the number of occurrences of \var{b} in \var{a}.
 117 \end{funcdesc}
 118
 119 \begin{funcdesc}{indexOf}{a, b}
 120 Return the index of the first of occurrence of \var{b} in \var{a}.
 121 \end{funcdesc}
 122
 123 \begin{funcdesc}{getitem}{a, b}
 124 \funcline{__getitem__}{a, b}
 125 Return the value of \var{a} at index \var{b}.
 126 \end{funcdesc}
 127
 128 \begin{funcdesc}{setitem}{a, b, c}
 129 \funcline{__setitem__}{a, b, c}
 130 Set the value of \var{a} at index \var{b} to \var{c}.
 131 \end{funcdesc}
 132
 133 \begin{funcdesc}{delitem}{a, b}
 134 \funcline{__delitem__}{a, b}
 135 Remove the value of \var{a} at index \var{b}.
 136 \end{funcdesc}
 137
 138 \begin{funcdesc}{getslice}{a, b, c}
 139 \funcline{__getslice__}{a, b, c}
 140 Return the slice of \var{a} from index \var{b} to index \var{c}\code{-1}.
 141 \end{funcdesc}
 142
 143 \begin{funcdesc}{setslice}{a, b, c, v}
 144 \funcline{__setslice__}{a, b, c, v}
 145 Set the slice of \var{a} from index \var{b} to index \var{c}\code{-1} to the
 146 sequence \var{v}.
 147 \end{funcdesc}
 148
 149 \begin{funcdesc}{delslice}{a, b, c}
 150 \funcline{__delslice__}{a, b, c}
 151 Delete the slice of \var{a} from index \var{b} to index \var{c}\code{-1}.
 152 \end{funcdesc}
 153
 154
 155 Example: Build a dictionary that maps the ordinals from \code{0} to
 156 \code{256} to their character equivalents.
 157
 158 \begin{verbatim}
 159 >>> import operator
 160 >>> d = {}
 161 >>> keys = range(256)
 162 >>> vals = map(chr, keys)
 163 >>> map(operator.setitem, [d]*len(keys), keys, vals)
 164 \end{verbatim}