import copy import sys # Fake a number that implements numeric methods through __coerce__ class CoerceNumber: def __init__(self, arg): self.arg = arg def __repr__(self): return '' % repr(self.arg) def __coerce__(self, other): if isinstance(other, CoerceNumber): return self.arg, other.arg else: return (self.arg, other) # Fake a number that implements numeric ops through methods. class MethodNumber: def __init__(self,arg): self.arg = arg def __repr__(self): return '' % repr(self.arg) def __add__(self,other): return self.arg + other def __radd__(self,other): return other + self.arg def __sub__(self,other): return self.arg - other def __rsub__(self,other): return other - self.arg def __mul__(self,other): return self.arg * other def __rmul__(self,other): return other * self.arg def __div__(self,other): return self.arg / other def __rdiv__(self,other): return other / self.arg def __pow__(self,other): return self.arg ** other def __rpow__(self,other): return other ** self.arg def __mod__(self,other): return self.arg % other def __rmod__(self,other): return other % self.arg def __cmp__(self, other): return cmp(self.arg, other) candidates = [ 2, 4.0, 2L, 2+0j, [1], (2,), None, MethodNumber(1), CoerceNumber(2)] infix_binops = [ '+', '-', '*', '/', '**', '%' ] prefix_binops = [ 'divmod' ] def do_infix_binops(): for a in candidates: for b in candidates: for op in infix_binops: print '%s %s %s' % (a, op, b), try: x = eval('a %s b' % op) except: error = sys.exc_info()[:2] print '... %s' % error[0] else: print '=', x try: z = copy.copy(a) except copy.Error: z = a # assume it has no inplace ops print '%s %s= %s' % (a, op, b), try: exec('z %s= b' % op) except: error = sys.exc_info()[:2] print '... %s' % error[0] else: print '=>', z def do_prefix_binops(): for a in candidates: for b in candidates: for op in prefix_binops: print '%s(%s, %s)' % (op, a, b), try: x = eval('%s(a, b)' % op) except: error = sys.exc_info()[:2] print '... %s' % error[0] else: print '=', x do_infix_binops() do_prefix_binops()