On 8/13/2014 10:20 PM, Ethan Furman wrote:
On 08/13/2014 07:01 PM, luofeiyu wrote:
help(int.__init__)
Help on wrapper_descriptor:
__init__(self, /, *args, **kwargs)
Initialize self. See help(type(self)) for accurate signature.
what is the "/" mean in __init__(self, /, *args, **kwargs) ?
The '/' means that all arguments before it must be positional only.
In particular, int.__init__(self = <subclass instance>) will not work
because 'self' is positional only. (I don't think int.__init__ actually
does anything, but a subclass of int might call it.)
This looks like an artifact of the new Argument Clinic for C code.
For example, if this also worked at the Python level, you could say:
def some_func(this, that, /, spam, eggs, *, foo, bar):
pass
Meaning that the first two parameters could not be specified by name,
the next two could be either name or position, and the last two by name
only.
Oh, and the * is valid Python now (the / is not -- it's solely a
documentation feature at this point).
I hope / will be valid Python in 3.5.
--
Terry Jan Reedy
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