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[Python-ideas] Pathlib additions & changes

Ryan Gonzalez rymg19 at gmail.com
Mon Jun 22 16:30:22 CEST 2015 
On June 22, 2015 3:30:26 AM CDT, David Townshend <aquavitae69 at gmail.com> wrote:
>Hi
>
>Recently I've been trying out pathlib in some real code, and while it
>is a
>vast improvement on messing around with os, os.path and shutil there
>are a
>couple of suggestions I'd like to make.
>
>** TL;DR: Add Path.copy, add Path.remove (replaces Path.rmdir and
>Path.unlink) and add flags to several methods.
>
>Details
>======
>
>1.  Add a copy method, i.e. source_path.copy(target_path), which by
>default
>should behave like shutil.copy2.
>
>2.  Why bother with the distinction between Path.unlink and Path.rmdir?
>Obviously they apply to different types of paths, but to a user, either
>way
>you just want to remove whatever is at the path, so perhaps just have a
>single Path.remove instead (but see point 3 below).
>
>3.  There are several other minor irritations where a common pattern
>requires several lines or the use of a lower-level library such as
>shutil.
>For example:
>
>*  Mkdir where path exists, but we don't care (common pattern on
>scripts)
>    if not path.exists():
>        path.mkdir(parent=True)

You can just do'

try:
    path.mkdir(parent=True)
except FileExistsError:
    pass

>
>  *  Recursively remove a directory (no sane way using pathlib alone)
>    shutil.rmtree(str(path))
>
>  *  Move a file, creating parents if necessary
>    py> if not target.parent.exists():
>            target.parent.mkdir(parents=true)
>        source.rename(target)
>
>There are others, but these are a couple that spring to mind.  There
>are
>three options.  Either we add a bunch of specific functions for each of
>these (e.g. Path.rmtree, Path.rename_with_mkdir, etc), or we add a
>whole
>lot of boolean arguments (e.g. Path.rename(make_parents=True), or we
>use
>flags, e.g. Path.rename(flags=MAKE_PARENTS)
>
>Using flags is, IMHO the neatest solution, and could replace some
>boolean
>arguments already included.  What follows is a suggestion of where
>flags
>might be useful, including the new methods suggested above.  I haven't
>put
>a huge amount of thought into these, wanting to just get the general
>idea
>on the table, so I'm sure that upon closer inspection some won't make
>much
>sense or could be better named.

I prefer keyword-only arguments. Flags aren't really Pythonic, IMO.

>
>    chmod: RECURSIVE | DONT_FOLLOW_SYMLINKS
> copy: WITH_STATS | MAKE_PARENTS | OVERWRITE_EXISTING | IGNORE_EXISTING
>    iterdir: RECURSIVE (maybe not worth it because of globbing)
>    lchmod: RECURSIVE (Could be dropped in favour of
>chmod(flags=DONT_FOLLOW_SYMLINKS))
>lstat: (Could be dropped in favour of stat(flags=DONT_FOLLOW_SYMLINKS))
>    mkdir: MAKE_PARENTS | OVERWRITE_EXISTING | IGNORE_EXISTING
>    remove: RECURSIVE
>    rename: MAKE_PARENTS | OVERWRITE_EXISTING | IGNORE_EXISTING
>replace: (Could be dropped in favour of
>rename(flags=OVERWRITE_EXISTING)
>)
>    rmdir: (Could be dropped in favour of remove)
>    stat: DONT_FOLLOW_SYMLINKS
>    touch: MAKE_PARENTS | IGNORE_EXISTING
>    unlink: (Could be dropped in favour of remove)
>
>Regards
>David
>
>
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>
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