[PATCH V2] pycompat: delay loading modules registered to stub

[Augie Fackler]

On Mon, Aug 15, 2016 at 07:06:20PM +0900, Yuya Nishihara wrote:
> # HG changeset patch
> # User Yuya Nishihara <yuya at tcha.org>
> # Date 1471153584 -32400
> #      Sun Aug 14 14:46:24 2016 +0900
> # Node ID 66bb317ce352edbc47c07d2b7f7553232aeb6723
> # Parent  0cb2d4db308b97e8fe7faa8d45a47b228037f230
> pycompat: delay loading modules registered to stub

Queued, thanks

>
> Replacement _pycompatstub is designed to be compatible with our demandimporter.
> try-except is replaced by version comparison because ImportError will no longer
> be raised immediately.
>
> diff --git a/mercurial/pycompat.py b/mercurial/pycompat.py
> --- a/mercurial/pycompat.py
> +++ b/mercurial/pycompat.py
> @@ -34,30 +34,32 @@ empty = _queue.Empty
>  queue = _queue.Queue
>
>  class _pycompatstub(object):
> -    pass
> -
> -def _alias(alias, origin, items):
> -    """ populate a _pycompatstub
> +    def __init__(self):
> +        self._aliases = {}
>
> -    copies items from origin to alias
> -    """
> -    for item in items:
> +    def _registeraliases(self, origin, items):
> +        """Add items that will be populated at the first access"""
> +        self._aliases.update((item.replace('_', '').lower(), (origin, item))
> +                             for item in items)
> +
> +    def __getattr__(self, name):
>          try:
> -            lcase = item.replace('_', '').lower()
> -            setattr(alias, lcase, getattr(origin, item))
> -        except AttributeError:
> -            pass
> +            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()
> -try:
> +if sys.version_info[0] < 3:
>      import BaseHTTPServer
>      import CGIHTTPServer
>      import SimpleHTTPServer
>      import urllib2
>      import urllib
> -    _alias(urlreq, urllib, (
> +    urlreq._registeraliases(urllib, (
>          "addclosehook",
>          "addinfourl",
>          "ftpwrapper",
> @@ -71,7 +73,7 @@ try:
>          "url2pathname",
>          "urlencode",
>      ))
> -    _alias(urlreq, urllib2, (
> +    urlreq._registeraliases(urllib2, (
>          "AbstractHTTPHandler",
>          "BaseHandler",
>          "build_opener",
> @@ -87,24 +89,24 @@ try:
>          "Request",
>          "urlopen",
>      ))
> -    _alias(urlerr, urllib2, (
> +    urlerr._registeraliases(urllib2, (
>          "HTTPError",
>          "URLError",
>      ))
> -    _alias(httpserver, BaseHTTPServer, (
> +    httpserver._registeraliases(BaseHTTPServer, (
>          "HTTPServer",
>          "BaseHTTPRequestHandler",
>      ))
> -    _alias(httpserver, SimpleHTTPServer, (
> +    httpserver._registeraliases(SimpleHTTPServer, (
>          "SimpleHTTPRequestHandler",
>      ))
> -    _alias(httpserver, CGIHTTPServer, (
> +    httpserver._registeraliases(CGIHTTPServer, (
>          "CGIHTTPRequestHandler",
>      ))
>
> -except ImportError:
> +else:
>      import urllib.request
> -    _alias(urlreq, urllib.request, (
> +    urlreq._registeraliases(urllib.request, (
>          "AbstractHTTPHandler",
>          "addclosehook",
>          "addinfourl",
> @@ -132,12 +134,12 @@ except ImportError:
>          "urlopen",
>      ))
>      import urllib.error
> -    _alias(urlerr, urllib.error, (
> +    urlerr._registeraliases(urllib.error, (
>          "HTTPError",
>          "URLError",
>      ))
>      import http.server
> -    _alias(httpserver, http.server, (
> +    httpserver._registeraliases(http.server, (
>          "HTTPServer",
>          "BaseHTTPRequestHandler",
>          "SimpleHTTPRequestHandler",
> diff --git a/tests/test-check-py3-compat.t b/tests/test-check-py3-compat.t
> --- a/tests/test-check-py3-compat.t
> +++ b/tests/test-check-py3-compat.t
> @@ -122,24 +122,22 @@
>    mercurial/hook.py: error importing: <TypeError> str expected, not bytes (error at i18n.py:*) (glob)
>    mercurial/httpconnection.py: error importing: <TypeError> str expected, not bytes (error at i18n.py:*) (glob)
>    mercurial/httppeer.py: error importing: <TypeError> str expected, not bytes (error at i18n.py:*) (glob)
> -  mercurial/keepalive.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/localrepo.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/lock.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/mail.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/manifest.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/match.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/mdiff.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/merge.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/minirst.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/namespaces.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/obsolete.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/patch.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/pathutil.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/peer.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/pure/mpatch.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/pure/parsers.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/pushkey.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> -  mercurial/pvec.py: error importing: <TypeError> getattr(): attribute name must be string (error at pycompat.py:*) (glob)
> +  mercurial/keepalive.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/localrepo.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/lock.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/mail.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/manifest.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/match.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/mdiff.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/merge.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/minirst.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/namespaces.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/obsolete.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/patch.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/pathutil.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/peer.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/pushkey.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> +  mercurial/pvec.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
>    mercurial/registrar.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
>    mercurial/repair.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
>    mercurial/repoview.py: error importing: <TypeError> getattr(): attribute name must be string (error at util.py:*) (glob)
> @@ -168,6 +166,6 @@
>    mercurial/verify.py: error importing: <TypeError> attribute name must be string, not 'bytes' (error at mdiff.py:*) (glob)
>    mercurial/win32.py: error importing module: <ImportError> No module named 'msvcrt' (line *) (glob)
>    mercurial/windows.py: error importing module: <ImportError> No module named 'msvcrt' (line *) (glob)
> -  mercurial/wireproto.py: error importing module: <TypeError> a bytes-like object is required, not 'str' (line *) (glob)
> +  mercurial/wireproto.py: error importing module: <TypeError> unorderable types: str() >= tuple() (line *) (glob)
>
>  #endif
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