On 04/10/2016 11:27 PM, Nick Coghlan wrote:
> On 11 April 2016 at 02:16, Ethan Furman <ethan at stoneleaf.us> wrote:
>>> DirEntry can still get the check, it can just throw TypeError when it
>>> represents a binary path (that's one of the advantages of using a
>>> method-based protocol - exceptions on method calls are more acceptable
>>> than exceptions on property access).
>>
>>
>> I guess I don't see the point of this. Either DirEntry's [1] only get
>> partial support (which is only marginally better than the no support pathlib
>> currently has), or stdlib code will need to catch those errors and then do
>> an isinstance check to see if knows what the type is and how to deal with it
>> [1].
>
> What's wrong with only gaining partial support? Standard library code
> that doesn't currently support DirEntry at all will gain the ability
> to support str-based DirEntry objects, while bytes-based DirEntry
> objects will continue to be a low level object [...]
Let's consider to functions, one that accepts bytes/str for the path,
and one that only accepts str:
str-only support
----------------
# before new protocol
def do_fritz(a_path):
if not isinstance(a_path, str):
raise TypeError('str required')
...
# after new protocol with str-only support
def do_fritz(a_path):
a_path = fspath(a_path)
...
# after new protocol with bytes/str support
a_path = fspath(a_path)
if not isinstance(a_path, str):
raise TypeError('str required')
...
bytes/str support
-----------------
# before new protocol
def zingar(a_path):
if not isinstance(a_path, (bytes,str)):
raise TypeError('bytes or str required')
...
# after new protocol with str-only support
def zingar(a_path):
if not isinstance(a_path, bytes):
try:
a_path = fspath(a_path)
except FSPathError:
raise TypeError('bytes or str required')
...
# after new protocol with bytes/str support
def zingar(a_path):
a_path = fspath(a_path)
if not isinstance(a_path, (bytes,str)):
raise TypeError('bytes or str required')
...
If those examples are anywhere close to accurate, an fspath protocol
that supported both bytes and str seems a lot easier to work with.
--
~Ethan~
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