pycompat: move multiline comments above a function to function doc

pycompat.py is unorganized and looks ugly. Next few patches will try to make it
look more cleaner so that adding more code is easy and reading code also.

This patch moves the multiline comments above functions to function docs. While
moving, I improved the comments and make them better suitable for func doc.

While I was here I drop a unrequired and misplaced comment.

mercurial/pycompat.py

@@ -1,450 +1,460 b''
 # pycompat.py - portability shim for python 3
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 """Mercurial portability shim for python 3.
 
 This contains aliases to hide python version-specific details from the core.
 """
 
 from __future__ import absolute_import
 
 import getopt
 import os
 import shlex
 import sys
 
 ispy3 = (sys.version_info[0] >= 3)
 
 if not ispy3:
     import cookielib
     import cPickle as pickle
     import httplib
     import Queue as _queue
     import SocketServer as socketserver
     import xmlrpclib
 else:
     import http.cookiejar as cookielib
     import http.client as httplib
     import pickle
     import queue as _queue
     import socketserver
     import xmlrpc.client as xmlrpclib
 
 def identity(a):
     return a
 
 if ispy3:
     import builtins
     import functools
     import io
     import struct
 
     fsencode = os.fsencode
     fsdecode = os.fsdecode
-    # A bytes version of os.name.
     oslinesep = os.linesep.encode('ascii')
     osname = os.name.encode('ascii')
     ospathsep = os.pathsep.encode('ascii')
     ossep = os.sep.encode('ascii')
     osaltsep = os.altsep
     if osaltsep:
         osaltsep = osaltsep.encode('ascii')
     # os.getcwd() on Python 3 returns string, but it has os.getcwdb() which
     # returns bytes.
     getcwd = os.getcwdb
     sysplatform = sys.platform.encode('ascii')
     sysexecutable = sys.executable
     if sysexecutable:
         sysexecutable = os.fsencode(sysexecutable)
     stringio = io.BytesIO
     maplist = lambda *args: list(map(*args))
 
     # TODO: .buffer might not exist if std streams were replaced; we'll need
     # a silly wrapper to make a bytes stream backed by a unicode one.
     stdin = sys.stdin.buffer
     stdout = sys.stdout.buffer
     stderr = sys.stderr.buffer
 
     # Since Python 3 converts argv to wchar_t type by Py_DecodeLocale() on Unix,
     # we can use os.fsencode() to get back bytes argv.
     #
     # https://hg.python.org/cpython/file/v3.5.1/Programs/python.c#l55
     #
     # TODO: On Windows, the native argv is wchar_t, so we'll need a different
     # workaround to simulate the Python 2 (i.e. ANSI Win32 API) behavior.
     if getattr(sys, 'argv', None) is not None:
         sysargv = list(map(os.fsencode, sys.argv))
 
     bytechr = struct.Struct('>B').pack
 
     class bytestr(bytes):
         """A bytes which mostly acts as a Python 2 str
 
         >>> bytestr(), bytestr(bytearray(b'foo')), bytestr(u'ascii'), bytestr(1)
         (b'', b'foo', b'ascii', b'1')
         >>> s = bytestr(b'foo')
         >>> assert s is bytestr(s)
 
         __bytes__() should be called if provided:
 
         >>> class bytesable(object):
         ...     def __bytes__(self):
         ...         return b'bytes'
         >>> bytestr(bytesable())
         b'bytes'
 
         There's no implicit conversion from non-ascii str as its encoding is
         unknown:
 
         >>> bytestr(chr(0x80)) # doctest: +ELLIPSIS
         Traceback (most recent call last):
           ...
         UnicodeEncodeError: ...
 
         Comparison between bytestr and bytes should work:
 
         >>> assert bytestr(b'foo') == b'foo'
         >>> assert b'foo' == bytestr(b'foo')
         >>> assert b'f' in bytestr(b'foo')
         >>> assert bytestr(b'f') in b'foo'
 
         Sliced elements should be bytes, not integer:
 
         >>> s[1], s[:2]
         (b'o', b'fo')
         >>> list(s), list(reversed(s))
         ([b'f', b'o', b'o'], [b'o', b'o', b'f'])
 
         As bytestr type isn't propagated across operations, you need to cast
         bytes to bytestr explicitly:
 
         >>> s = bytestr(b'foo').upper()
         >>> t = bytestr(s)
         >>> s[0], t[0]
         (70, b'F')
 
         Be careful to not pass a bytestr object to a function which expects
         bytearray-like behavior.
 
         >>> t = bytes(t)  # cast to bytes
         >>> assert type(t) is bytes
         """
 
         def __new__(cls, s=b''):
             if isinstance(s, bytestr):
                 return s
             if (not isinstance(s, (bytes, bytearray))
                 and not hasattr(s, u'__bytes__')):  # hasattr-py3-only
                 s = str(s).encode(u'ascii')
             return bytes.__new__(cls, s)
 
         def __getitem__(self, key):
             s = bytes.__getitem__(self, key)
             if not isinstance(s, bytes):
                 s = bytechr(s)
             return s
 
         def __iter__(self):
             return iterbytestr(bytes.__iter__(self))
 
     def iterbytestr(s):
         """Iterate bytes as if it were a str object of Python 2"""
         return map(bytechr, s)
 
     def sysbytes(s):
         """Convert an internal str (e.g. keyword, __doc__) back to bytes
 
         This never raises UnicodeEncodeError, but only ASCII characters
         can be round-trip by sysstr(sysbytes(s)).
         """
         return s.encode(u'utf-8')
 
     def sysstr(s):
         """Return a keyword str to be passed to Python functions such as
         getattr() and str.encode()
 
         This never raises UnicodeDecodeError. Non-ascii characters are
         considered invalid and mapped to arbitrary but unique code points
         such that 'sysstr(a) != sysstr(b)' for all 'a != b'.
         """
         if isinstance(s, builtins.str):
             return s
         return s.decode(u'latin-1')
 
     def strurl(url):
         """Converts a bytes url back to str"""
         return url.decode(u'ascii')
 
     def bytesurl(url):
         """Converts a str url to bytes by encoding in ascii"""
         return url.encode(u'ascii')
 
     def raisewithtb(exc, tb):
         """Raise exception with the given traceback"""
         raise exc.with_traceback(tb)
 
     def getdoc(obj):
         """Get docstring as bytes; may be None so gettext() won't confuse it
         with _('')"""
         doc = getattr(obj, u'__doc__', None)
         if doc is None:
             return doc
         return sysbytes(doc)
 
     def _wrapattrfunc(f):
         @functools.wraps(f)
         def w(object, name, *args):
             return f(object, sysstr(name), *args)
         return w
 
     # these wrappers are automagically imported by hgloader
     delattr = _wrapattrfunc(builtins.delattr)
     getattr = _wrapattrfunc(builtins.getattr)
     hasattr = _wrapattrfunc(builtins.hasattr)
     setattr = _wrapattrfunc(builtins.setattr)
     xrange = builtins.range
     unicode = str
 
     def open(name, mode='r', buffering=-1):
         return builtins.open(name, sysstr(mode), buffering)
 
-    # getopt.getopt() on Python 3 deals with unicodes internally so we cannot
-    # pass bytes there. Passing unicodes will result in unicodes as return
-    # values which we need to convert again to bytes.
     def getoptb(args, shortlist, namelist):
+        """
+        Takes bytes arguments, converts them to unicode, pass them to
+        getopt.getopt(), convert the returned values back to bytes and then
+        return them for Python 3 compatibility as getopt.getopt() don't accepts
+        bytes on Python 3.
+        """
         args = [a.decode('latin-1') for a in args]
         shortlist = shortlist.decode('latin-1')
         namelist = [a.decode('latin-1') for a in namelist]
         opts, args = getopt.getopt(args, shortlist, namelist)
         opts = [(a[0].encode('latin-1'), a[1].encode('latin-1'))
                 for a in opts]
         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 takes keyword arguments, convert the keys to str.
     def strkwargs(dic):
+        """
+        Converts the keys of a python dictonary to str i.e. unicodes so that
+        they can be passed as keyword arguments as dictonaries with bytes keys
+        can't be passed as keyword arguments to functions on Python 3.
+        """
         dic = dict((k.decode('latin-1'), v) for k, v in dic.iteritems())
         return dic
 
-    # keys of keyword arguments need to be unicode while passing into
-    # a function. This function helps us to convert those keys back to bytes
-    # again as we need to deal with bytes.
     def byteskwargs(dic):
+        """
+        Converts keys of python dictonaries to bytes as they were converted to
+        str to pass that dictonary as a keyword argument on Python 3.
+        """
         dic = dict((k.encode('latin-1'), v) for k, v in dic.iteritems())
         return dic
 
-    # shlex.split() accepts unicodes on Python 3. This function takes bytes
-    # argument, convert it into unicodes, pass into shlex.split(), convert the
-    # returned value to bytes and return that.
     # TODO: handle shlex.shlex().
     def shlexsplit(s):
+        """
+        Takes bytes argument, convert it to str i.e. unicodes, pass that into
+        shlex.split(), convert the returned value to bytes and return that for
+        Python 3 compatibility as shelx.split() don't accept bytes on Python 3.
+        """
         ret = shlex.split(s.decode('latin-1'))
         return [a.encode('latin-1') for a in ret]
 
 else:
     import cStringIO
 
     bytechr = chr
     bytestr = str
     iterbytestr = iter
     sysbytes = identity
     sysstr = identity
     strurl = identity
     bytesurl = identity
 
     # this can't be parsed on Python 3
     exec('def raisewithtb(exc, tb):\n'
          '    raise exc, None, tb\n')
 
-    # Partial backport from os.py in Python 3, which only accepts bytes.
-    # In Python 2, our paths should only ever be bytes, a unicode path
-    # indicates a bug.
     def fsencode(filename):
+        """
+        Partial backport from os.py in Python 3, which only accepts bytes.
+        In Python 2, our paths should only ever be bytes, a unicode path
+        indicates a bug.
+        """
         if isinstance(filename, str):
             return filename
         else:
             raise TypeError(
                 "expect str, not %s" % type(filename).__name__)
 
     # In Python 2, fsdecode() has a very chance to receive bytes. So it's
     # better not to touch Python 2 part as it's already working fine.
     fsdecode = identity
 
     def getdoc(obj):
         return getattr(obj, '__doc__', None)
 
     def getoptb(args, shortlist, namelist):
         return getopt.getopt(args, shortlist, namelist)
 
     strkwargs = identity
     byteskwargs = identity
 
     oslinesep = os.linesep
     osname = os.name
     ospathsep = os.pathsep
     ossep = os.sep
     osaltsep = os.altsep
     stdin = sys.stdin
     stdout = sys.stdout
     stderr = sys.stderr
     if getattr(sys, 'argv', None) is not None:
         sysargv = sys.argv
     sysplatform = sys.platform
     getcwd = os.getcwd
     sysexecutable = sys.executable
     shlexsplit = shlex.split
     stringio = cStringIO.StringIO
     maplist = map
 
 empty = _queue.Empty
 queue = _queue.Queue
 
 class _pycompatstub(object):
     def __init__(self):
         self._aliases = {}
 
     def _registeraliases(self, origin, items):
         """Add items that will be populated at the first access"""
         items = map(sysstr, items)
         self._aliases.update(
             (item.replace(sysstr('_'), sysstr('')).lower(), (origin, item))
             for item in items)
 
     def _registeralias(self, origin, attr, name):
         """Alias ``origin``.``attr`` as ``name``"""
         self._aliases[sysstr(name)] = (origin, sysstr(attr))
 
     def __getattr__(self, name):
         try:
             origin, item = self._aliases[name]
         except KeyError:
             raise AttributeError(name)
         self.__dict__[name] = obj = getattr(origin, item)
         return obj
 
 httpserver = _pycompatstub()
 urlreq = _pycompatstub()
 urlerr = _pycompatstub()
 if not ispy3:
     import BaseHTTPServer
     import CGIHTTPServer
     import SimpleHTTPServer
     import urllib2
     import urllib
     import urlparse
     urlreq._registeraliases(urllib, (
         "addclosehook",
         "addinfourl",
         "ftpwrapper",
         "pathname2url",
         "quote",
         "splitattr",
         "splitpasswd",
         "splitport",
         "splituser",
         "unquote",
         "url2pathname",
         "urlencode",
     ))
     urlreq._registeraliases(urllib2, (
         "AbstractHTTPHandler",
         "BaseHandler",
         "build_opener",
         "FileHandler",
         "FTPHandler",
         "HTTPBasicAuthHandler",
         "HTTPDigestAuthHandler",
         "HTTPHandler",
         "HTTPPasswordMgrWithDefaultRealm",
         "HTTPSHandler",
         "install_opener",
         "ProxyHandler",
         "Request",
         "urlopen",
     ))
     urlreq._registeraliases(urlparse, (
         "urlparse",
         "urlunparse",
     ))
     urlerr._registeraliases(urllib2, (
         "HTTPError",
         "URLError",
     ))
     httpserver._registeraliases(BaseHTTPServer, (
         "HTTPServer",
         "BaseHTTPRequestHandler",
     ))
     httpserver._registeraliases(SimpleHTTPServer, (
         "SimpleHTTPRequestHandler",
     ))
     httpserver._registeraliases(CGIHTTPServer, (
         "CGIHTTPRequestHandler",
     ))
 
 else:
     import urllib.parse
     urlreq._registeraliases(urllib.parse, (
         "splitattr",
         "splitpasswd",
         "splitport",
         "splituser",
         "urlparse",
         "urlunparse",
     ))
     urlreq._registeralias(urllib.parse, "unquote_to_bytes", "unquote")
     import urllib.request
     urlreq._registeraliases(urllib.request, (
         "AbstractHTTPHandler",
         "BaseHandler",
         "build_opener",
         "FileHandler",
         "FTPHandler",
         "ftpwrapper",
         "HTTPHandler",
         "HTTPSHandler",
         "install_opener",
         "pathname2url",
         "HTTPBasicAuthHandler",
         "HTTPDigestAuthHandler",
         "HTTPPasswordMgrWithDefaultRealm",
         "ProxyHandler",
         "Request",
         "url2pathname",
         "urlopen",
     ))
     import urllib.response
     urlreq._registeraliases(urllib.response, (
         "addclosehook",
         "addinfourl",
     ))
     import urllib.error
     urlerr._registeraliases(urllib.error, (
         "HTTPError",
         "URLError",
     ))
     import http.server
     httpserver._registeraliases(http.server, (
         "HTTPServer",
         "BaseHTTPRequestHandler",
         "SimpleHTTPRequestHandler",
         "CGIHTTPRequestHandler",
     ))
 
     # urllib.parse.quote() accepts both str and bytes, decodes bytes
     # (if necessary), and returns str. This is wonky. We provide a custom
     # implementation that only accepts bytes and emits bytes.
     def quote(s, safe=r'/'):
         s = urllib.parse.quote_from_bytes(s, safe=safe)
         return s.encode('ascii', 'strict')
 
     # urllib.parse.urlencode() returns str. We use this function to make
     # sure we return bytes.
     def urlencode(query, doseq=False):
             s = urllib.parse.urlencode(query, doseq=doseq)
             return s.encode('ascii')
 
     urlreq.quote = quote
     urlreq.urlencode = urlencode