[PATCH 2 of 3 V2] py3: utility functions to convert keys of kwargs to bytes/unicodes

Yuya Nishihara yuya at tcha.org
Thu Dec 8 10:22:12 EST 2016


On Thu, 8 Dec 2016 20:37:07 +0530, Pulkit Goyal wrote:
> On Thu, Dec 8, 2016 at 8:32 PM, Yuya Nishihara <yuya at tcha.org> wrote:
> > On Thu, 08 Dec 2016 00:06:40 +0530, Pulkit Goyal wrote:
> >> # HG changeset patch
> >> # User Pulkit Goyal <7895pulkit at gmail.com>
> >> # Date 1481127783 -19800
> >> #      Wed Dec 07 21:53:03 2016 +0530
> >> # Node ID 85d610c83bda09dea2393c22e415dd9656f5a7f2
> >> # Parent  ced854b9dfaa7298b241ac085627b12ecb796dcd
> >> py3: utility functions to convert keys of kwargs to bytes/unicodes
> >
> >> --- a/mercurial/pycompat.py   Tue Dec 06 06:36:36 2016 +0530
> >> +++ b/mercurial/pycompat.py   Wed Dec 07 21:53:03 2016 +0530
> >> @@ -103,6 +103,22 @@
> >>          args = [a.encode('latin-1') for a in args]
> >>          return opts, args
> >>
> >> +    # keys of keyword arguments in Python need to be strings which are unicodes
> >> +    # Python 3. This function take keyword arguments, convert the keys to str
> >> +    # if they are in bytes.
> >> +    def strkwargs(dic):
> >> +        dic = {(k.decode('latin-1') if isinstance(k, bytes) else k): v
> >> +                                                    for k, v in dic.items()}
> >> +        return dic
> >> +
> >> +    # keys of keyword arguments need to be unicode while passing into a
> >> +    # a function. This function helps us to convert those keys back to bytes
> >> +    # again as we need to deal with bytes.
> >> +    def byteskwargs(dic):
> >> +        dic = {(k.encode('latin-1') if isinstance(k, str) else k): v
> >> +                                                    for k, v in dic.items()}
> >> +        return dic
> >
> > I think we can assume the type of keys must be either bytes or unicode, so
> > we won't need isinstance() checks.
> 
> On python 3, if passed value is bytes, then .encode() will result in
> error. So have to specific on Python 3.

IMHO, it's a kind of programming error. Unlike pycompat.getattr(), strkwargs()
isn't a drop-in replacement for a standard function, so we can say strkwargs()
only takes a dict of bytes keys.

> > And no dict comprehension. The code must be parseable by Python 2.6.
> 
> Yeah I remember, actually this code is under a if statement which is
> executed if sys.version >= 3.

Dict comprehension is syntax. Runtime dispatch can't stop parsing of the
ispy3 block.


More information about the Mercurial-devel mailing list