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Wow, I haven't heard of pathlib [1] before now, but it looks awesome! In particular, using the slash operator to join paths is brilliant. >>> p = PurePath(

Wow, I haven't heard of pathlib [1] before now, but it looks awesome! In particular, using the slash operator to join paths is brilliant. >>> p = PurePath('/etc') >>> p / 'init.d' / 'apache2' PurePosixPath('/etc/init.d/apache2') [1]: http://docs.python.org/3.4/library/pathlib.html http://docs.python.org/3.4/library/pathlib.html

bodyfour 13y ago
FWIW, the boost::filesystem C++ package uses the / operator in the same way
yareally 13y ago
Scala does something similarly neat with using #| for piping system commands. Slash for Scala is not used by default though for path joining, but it can be by adding an implicit function: implicit def slash(str: String) = new { def /(joinStr: String) = str + java.io.File.separatorChar + joinStr} val joinedStr = "abc"/"def"/"ghi" > joinedStr : java.lang.String = abc/def/ghi Shell friendly syntax can be used for stdin/stdout in Scala as well (already in the stdlib with no implicits required): #< Redirect STDIN #> Redirect STDOUT #>> Append to STDOUT #&& Create an AND list #!! Create an OR list http://stackoverflow.com/questions/12772605/scala-shell-commands-with-pipe/12772628 http://stackoverflow.com/questions/12772605/scala-shell-comm... http://alvinalexander.com/scala/scala-execute-exec-external-system-commands-in-scala http://alvinalexander.com/scala/scala-execute-exec-external-...
- d0mine 13y ago
  There are Plumbum shell combinators in Python http://plumbum.readthedocs.org/en/latest/ http://plumbum.readthedocs.org/en/latest/
  - voltagex_ 13y ago
    There are a couple of modules that do this kind of thing but Plumbum looks interesting, particularly http://plumbum.readthedocs.org/en/latest/local_commands.html#import-hack http://plumbum.readthedocs.org/en/latest/local_commands.html... >from plumbum.cmd import cat >>cat('tmp.txt') #invokes cat tmp.txt on the system
yen223 13y ago
One of the many things I like about Python is their pragmatic approach to operator overloading. Well, their pragmatic approach to everything, really.
avdd_ 13y ago
No one objected to using "pure" instead of the more common "abstract" (which is the actual antonym of "concrete") ?? Why do people do this?
- CUViper 13y ago
  Concrete paths inherit from pure paths - this would be quite strange using antonyms. This isn't like an "abstract" base class. It's a full class on its own, which is extended by another. Anyway, I think it's meant to be "pure" like pure functions, generally having no side effects or external inputs. https://en.wikipedia.org/wiki/Pure_function https://en.wikipedia.org/wiki/Pure_function
  - quesebifurcan 13y ago
    i think so too. like it says in the docs: "Regardless of the system you’re running on, you can instantiate all of these classes, since they don’t provide any operation that does system calls." http://docs.python.org/3.4/library/pathlib.html#pure-paths http://docs.python.org/3.4/library/pathlib.html#pure-paths
reinhardt 13y ago
The precursor path library [1] by J. Orendorff had the slash operator overloading trick a decade (or more) ago. [1] https://pypi.python.org/pypi/path.py/1.2 https://pypi.python.org/pypi/path.py/1.2
thristian 13y ago
I hadn't heard of it either, although I have played with Twisted's FilePath[1] class previously. I didn't really understand the attraction of an OO filesystem API until I actually used it in anger and realised how handy it was that all the relevant functions were on the object I was messing with, instead of arbitrarily divided between the "os" and "os.path" modules. Some (hopefully constructive) suggestions for the pathlib API: - Python 3 dicts ditched .iterkeys(), .itervalues() and .iteritems(); why does pathlib use the clumsy .iterdir() when it could just be called .children? - Like many Python programmers (I assume), I'm more familiar with POSIX command-line tools than I am with POSIX APIs. Command-line tools generally have an option to control whether they dereference symlinks (cp -L, find -L, etc) rather than having a separate. parallel tool that does the same thing. I think it would be neater if .lstat() and .lchmod() were removed in favour of a "follow_symlinks" parameter to .stat() and .chmod() (and .is_dir() and .touch() and .owner(), and, and, and..) - If you're going to have convenience functions that pick out interesting bits from the .stat() return value, I would find .size() far more practical than .is_socket() [1]: http://twistedmatrix.com/documents/current/api/twisted.python.filepath.FilePath.html http://twistedmatrix.com/documents/current/api/twisted.pytho...
Flimm 13y ago
I thought operator overloading like that was considered bad practise. It seems to me that the + operator should have been overloaded, not the / operator.

bodyfour 13y ago

FWIW, the boost::filesystem C++ package uses the / operator in the same way

yareally 13y ago

Scala does something similarly neat with using #| for piping system commands. Slash for Scala is not used by default though for path joining, but it can be by adding an implicit function: implicit def slash(str: String) = new { def /(joinStr: String) = str + java.io.File.separatorChar + joinStr} val joinedStr = "abc"/"def"/"ghi" > joinedStr : java.lang.String = abc/def/ghi Shell friendly syntax can be used for stdin/stdout in Scala as well (already in the stdlib with no implicits required): #< Redirect STDIN #> Redirect STDOUT #>> Append to STDOUT #&& Create an AND list #!! Create an OR list http://stackoverflow.com/questions/12772605/scala-shell-commands-with-pipe/12772628 http://stackoverflow.com/questions/12772605/scala-shell-comm... http://alvinalexander.com/scala/scala-execute-exec-external-system-commands-in-scala http://alvinalexander.com/scala/scala-execute-exec-external-...

d0mine 13y ago
There are Plumbum shell combinators in Python http://plumbum.readthedocs.org/en/latest/ http://plumbum.readthedocs.org/en/latest/
- voltagex_ 13y ago
  There are a couple of modules that do this kind of thing but Plumbum looks interesting, particularly http://plumbum.readthedocs.org/en/latest/local_commands.html#import-hack http://plumbum.readthedocs.org/en/latest/local_commands.html... >from plumbum.cmd import cat >>cat('tmp.txt') #invokes cat tmp.txt on the system

yen223 13y ago

One of the many things I like about Python is their pragmatic approach to operator overloading. Well, their pragmatic approach to everything, really.

avdd_ 13y ago

No one objected to using "pure" instead of the more common "abstract" (which is the actual antonym of "concrete") ?? Why do people do this?

CUViper 13y ago
Concrete paths inherit from pure paths - this would be quite strange using antonyms. This isn't like an "abstract" base class. It's a full class on its own, which is extended by another. Anyway, I think it's meant to be "pure" like pure functions, generally having no side effects or external inputs. https://en.wikipedia.org/wiki/Pure_function https://en.wikipedia.org/wiki/Pure_function
- quesebifurcan 13y ago
  i think so too. like it says in the docs: "Regardless of the system you’re running on, you can instantiate all of these classes, since they don’t provide any operation that does system calls." http://docs.python.org/3.4/library/pathlib.html#pure-paths http://docs.python.org/3.4/library/pathlib.html#pure-paths

reinhardt 13y ago

The precursor path library [1] by J. Orendorff had the slash operator overloading trick a decade (or more) ago. [1] https://pypi.python.org/pypi/path.py/1.2 https://pypi.python.org/pypi/path.py/1.2

thristian 13y ago

I hadn't heard of it either, although I have played with Twisted's FilePath[1] class previously. I didn't really understand the attraction of an OO filesystem API until I actually used it in anger and realised how handy it was that all the relevant functions were on the object I was messing with, instead of arbitrarily divided between the "os" and "os.path" modules. Some (hopefully constructive) suggestions for the pathlib API: - Python 3 dicts ditched .iterkeys(), .itervalues() and .iteritems(); why does pathlib use the clumsy .iterdir() when it could just be called .children? - Like many Python programmers (I assume), I'm more familiar with POSIX command-line tools than I am with POSIX APIs. Command-line tools generally have an option to control whether they dereference symlinks (cp -L, find -L, etc) rather than having a separate. parallel tool that does the same thing. I think it would be neater if .lstat() and .lchmod() were removed in favour of a "follow_symlinks" parameter to .stat() and .chmod() (and .is_dir() and .touch() and .owner(), and, and, and..) - If you're going to have convenience functions that pick out interesting bits from the .stat() return value, I would find .size() far more practical than .is_socket() [1]: http://twistedmatrix.com/documents/current/api/twisted.python.filepath.FilePath.html http://twistedmatrix.com/documents/current/api/twisted.pytho...

Flimm 13y ago

I thought operator overloading like that was considered bad practise. It seems to me that the + operator should have been overloaded, not the / operator.