[Python-ideas] Add list.join() please

[Robert Vanden Eynde]

+1 to that email !! (how to do that in email haha)

On Tue, 29 Jan 2019, 21:50 Chris Barker via Python-ideas <
python-ideas at python.org wrote:

> A couple notes:
>
> On Tue, Jan 29, 2019 at 5:31 AM Jamesie Pic <jpic at yourlabs.org> wrote:
>
>> can you clarify the documentation
>> topic you think should be improved or created ? "Assembling strings"
>>
>
> I would think "assembling strings", though there is a lot out there
> already.
>
>
>> or "inconsistencies between os.path.join and str.join" ?
>>
>
> well, if we're talking about moving forward, then the Path object is
> probably the "right" way to join paths anyway :-)
>
> a_path / "a_dir" / "a_filename"
>
> But to the core language issue -- I started using Python with 1.5.* and
> back then join() was in the string module (and is there in 2.7 still)
>
> And yes, I did expect it to be a list method...
>
> Then it was added as a method of the string object.
>
> And I thought THAT was odd -- be really appreciated that I didn't need to
> import a module to do something fundamental.
>
> But the fact is, that joining strings is fundamentally a string operation,
> so it makes sense for it to be there.
>
> In earlier py2, I would have thought, maybe it should be a list method --
> it's pretty darn common to join lists of strings, yes? But what about
> tuples? Python was kind of all about sequences -- so maybe all sequences
> could have that method -- i.e part of the sequence ABC.
>
> But with > py3k, Python is more about iterables than sequences -- and join
> (and many other methods and functions) operate on any iterable -- and this
> is a really good thing.
>
> So add join to ALL iterables? That makes little sense, and really isn't
> possible -- an iterable is something that conforms to the iterator protocol
> -- it's not a type, or even an ABC.
>
> So in the end, join really does only make sense as string method.
>
> Or Maybe as a built in -- but we really don't need any more of those.
>
> If you want to argue that str.join() should take multiple arguments, like
> os.path.join does, then, well we could do that -- it currently takes one
> and only one argument, so it could be extended to join multiple arguments
> -- but I have hardly ever seem a use case for that.
>
> The mistake I'm still doing after 10 years of Python
>>
>
> hmm -- I've seen a lot of newbies struggle with this, but haven't had an
> issue with it for years myself.
>
>
>>     >>> '/'.join('some', 'path')
>>     TypeError: join() takes exactly one argument (2 given)
>>
>
> pathlib aside, that really isn't the right way to join paths .....
> os.path.jon exists for a (good) reasons. One of which is this:
>
> In [22]: os.path.join("this/", "that")
> Out[22]: 'this/that'
>
> -CHB
>
>
> --
>
> Christopher Barker, Ph.D.
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>
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