Entering
>>>dir(5)
I get
['__abs__', '__add__', '__and__', '__class__', '__cmp__', '__coerce__',
'__delattr__', '__div__', '__divmod__', '__doc__', '__float__',
'__floordiv__', '__getattribute__', '__getnewargs__', '__hash__',
'__hex__', '__init__', '__int__', '__invert__', '__long__',
'__lshift__', '__mod__', '__mul__', '__neg__', '__new__',
'__nonzero__', '__oct__', '__or__', '__pos__', '__pow__', '__radd__',
'__rand__', '__rdiv__', '__rdivmod__', '__reduce__', '__reduce_ex__',
'__repr__', '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__',
'__ror__', '__rpow__', '__rrshift__', '__rshift__', '__rsub__',
'__rtruediv__', '__rxor__', '__setattr__', '__str__', '__sub__',
'__truediv__', '__xor__']
Every time I use dir(some module) I get a lot of attributes with double
underscore, for example __add__. Ok, I thought __add__ must be a method
which I can apply like this
>>> 5.__add(8)
However Python responded
SyntaxError: invalid syntax
I tried
>>> help(5.__add__)
but got
SyntaxError: invalid syntax
However when I tried with a list
>>> help([5,6].__add__)
I got
Help on method-wrapper object:
__add__ = class method-wrapper(object)
| Methods defined here:
|
| __call__(...)
| x.__call__(...) <==> x(...)
|
| __getattribute__(...)
| x.__getattribute__('name') <==> x.name
Not that I understand much of this but at least I got some response.
Now I went to Python Library Reference and searched for "__add__" but
got zero hits.
Could someone explain the use of __add__ (and similar double underscore
attributes) and what their use is.
Bob
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