Lib/test/test_coercion.py

   1 import copy
   2 import sys
   3
   4 # Fake a number that implements numeric methods through __coerce__
   5 class CoerceNumber:
   6     def __init__(self, arg):
   7         self.arg = arg
   8
   9     def __repr__(self):
  10         return '<CoerceNumber %s>' % repr(self.arg)
  11
  12     def __coerce__(self, other):
  13         if isinstance(other, CoerceNumber):
  14             return self.arg, other.arg
  15         else:
  16             return (self.arg, other)
  17
  18
  19 # Fake a number that implements numeric ops through methods.
  20 class MethodNumber:
  21
  22     def __init__(self,arg):
  23         self.arg = arg
  24
  25     def __repr__(self):
  26         return '<MethodNumber %s>' % repr(self.arg)
  27
  28     def __add__(self,other):
  29         return self.arg + other
  30
  31     def __radd__(self,other):
  32         return other + self.arg
  33
  34     def __sub__(self,other):
  35         return self.arg - other
  36
  37     def __rsub__(self,other):
  38         return other - self.arg
  39
  40     def __mul__(self,other):
  41         return self.arg * other
  42
  43     def __rmul__(self,other):
  44         return other * self.arg
  45
  46     def __div__(self,other):
  47         return self.arg / other
  48
  49     def __rdiv__(self,other):
  50         return other / self.arg
  51
  52     def __pow__(self,other):
  53         return self.arg ** other
  54
  55     def __rpow__(self,other):
  56         return other ** self.arg
  57
  58     def __mod__(self,other):
  59         return self.arg % other
  60
  61     def __rmod__(self,other):
  62         return other % self.arg
  63
  64     def __cmp__(self, other):
  65         return cmp(self.arg, other)
  66
  67
  68 candidates = [ 2, 4.0, 2L, 2+0j, [1], (2,), None,
  69                MethodNumber(1), CoerceNumber(2)]
  70
  71 infix_binops = [ '+', '-', '*', '/', '**', '%' ]
  72 prefix_binops = [ 'divmod' ]
  73
  74 def do_infix_binops():
  75     for a in candidates:
  76         for b in candidates:
  77             for op in infix_binops:
  78                 print '%s %s %s' % (a, op, b),
  79                 try:
  80                     x = eval('a %s b' % op)
  81                 except:
  82                     error = sys.exc_info()[:2]
  83                     print '... %s' % error[0]
  84                 else:
  85                     print '=', x
  86                 try:
  87                     z = copy.copy(a)
  88                 except copy.Error:
  89                     z = a # assume it has no inplace ops
  90                 print '%s %s= %s' % (a, op, b),
  91                 try:
  92                     exec('z %s= b' % op)
  93                 except:
  94                     error = sys.exc_info()[:2]
  95                     print '... %s' % error[0]
  96                 else:
  97                     print '=>', z
  98
  99 def do_prefix_binops():
 100     for a in candidates:
 101         for b in candidates:
 102             for op in prefix_binops:
 103                 print '%s(%s, %s)' % (op, a, b),
 104                 try:
 105                     x = eval('%s(a, b)' % op)
 106                 except:
 107                     error = sys.exc_info()[:2]
 108                     print '... %s' % error[0]
 109                 else:
 110                     print '=', x
 111
 112 do_infix_binops()
 113 do_prefix_binops()