On Tue, 16 Jun 2015 13:45:01 +0100, Oscar Benjamin wrote:
> On 16 June 2015 at 09:18, Steven D'Aprano
> <steve+comp.lang.pyt...@pearwood.info> wrote:
>>
>> The primary use-case (at least *my* use-case, and hopefully others) is
>> to have "from module import edir as dir" in their Python startup file.
>> That means that when running interactively, they will get the enhanced
>> version of dir, but when running a script or an application they'll
>> just get the regular one.
>>
>> (Ideally, the regular one will eventually gain the same superpowers as
>> edir has, but that's a discussion for another day.)
>>
>> Besides, apart from the inspect module, which probably shouldn't, who
>> uses dir() programmatically?
>>
>> (If you do, you'll be glad to hear that edir() behaves the same as
>> regular dir() by default.)
>
> What's the point in giving edir two modes if one of them is the same as
> dir? You could just do "from module import edir" and then use dir/edir
> as desired.
Oh ye of little faith :-)
I practically live in the Python interactive interpreter, and this has
evolved from functionality I have wished dir has. It's a lot more than
just whether or not dunders are displayed by default.
The most important feature of edir() is that it supports globbing and
substring matches:
py> dir("", "low")
['islower', 'lower']
py> dir('', '*er')
['center', 'isidentifier', 'islower', 'isupper', 'lower', 'upper']
By default, globs are case-insensitive, but you can force them to be case-
sensitive with a metachar. I added this because I kept coming across
classes with methods that used CamelCase when I expected lowercase. It
understands the standard metacharacters ? * and [] as well as prefixes !
to invert the match and = to force case-sensitivity.
It also optionally includes the metaclass of the object. This was
requested by somebody else as standard behaviour for dir, on python-ideas
and the bug tracker, but rejected.
The reason this was requested is that dir() intentionally doesn't return
all the attributes visible from an object:
py> "mro" in dir(str)
False
py> str.mro
<built-in method mro of type object at 0x81db360>
I thought it seemed like an interesting idea, and added it as an option
with a keyword-only argument:
py> "mro" in dir(str, meta=True)
True
but frankly I'm not entirely sure this feature is useful. Time will tell.
> Personally I just use ipython's tab-completion instead of dir. It shows
> the dunders if you first type underscores but hides them otherwise e.g.:
Tab completion is great, but it solves a different problem. One with some
overlap, admittedly, but still different.
--
Steven D'Aprano
--
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