[Python-ideas] Add list.join() please
MRAB
python at mrabarnett.plus.com
Tue Jan 29 19:12:05 EST 2019
On 2019-01-29 23:30, Terry Reedy wrote:
> On 1/28/2019 8:40 PM, Jamesie Pic wrote:
>
> > 0. os.path.join takes *args
>
> Since at least 1 path is required, the signature is join(path, *paths).
> I presume that this is the Python version of the Unix version of the
> system call that it wraps.. The hidden argument is os.sep. It is
> equivalent to os.sep.join((path,)+paths) (though one would not write it
> this way).
>
>> 1. str.join takes a list argument,
>
> This premise behind the (repeated) request is a false. str.joins
> arguments are a string (the joiner) and an *iterable of strings*, which
> is an abstract subclass of the abstract concept 'iterable'. And only a
> small fraction of lists are lists of strings and therefore iterables of
> strings.
>
One the examples given was writing:
>>> '/'.join('some', 'path')
To me, this suggests that what the OP _really_ wants is for str.join to
accept multiple arguments, much as os.path.join does.
I thought that there would be a problem with that because currently the
single argument is an iterable, and you wouldn't want to iterate the
first argument of '/'.join('some', 'path').
However, both min and max will accept either a single argument that's
iterated over or multiple arguments that are not, so there's a precedent
there.
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