[PATCH 1 of 7 path-configs] ui: create paths classes to hold path information

[Sean Farley]

Gregory Szorc writes:

> # HG changeset patch
> # User Gregory Szorc <gregory.szorc at gmail.com>
> # Date 1423338328 28800
> #      Sat Feb 07 11:45:28 2015 -0800
> # Node ID 425462525dc5c44de575084d1516417286c43f51
> # Parent  ff5caa8dfd993680d9602ca6ebb14da9de10d5f4
> ui: create paths classes to hold path information
>
> Upcoming patches will give paths more features and more flexibility.
> We start the process like how we solve many problems in computer
> science: by adding a layer of indirection. We introduce a "paths"
> class that is a collection and interface to defined paths. We also
> introduce the "path" class to hold information about single path
> instances.
>
> diff --git a/mercurial/ui.py b/mercurial/ui.py
> --- a/mercurial/ui.py
> +++ b/mercurial/ui.py
> @@ -5,9 +5,9 @@
>  # This software may be used and distributed according to the terms of the
>  # GNU General Public License version 2 or any later version.
>  
>  from i18n import _
> -import errno, getpass, os, socket, sys, tempfile, traceback
> +import errno, getpass, os, socket, sys, tempfile, traceback, weakref
>  import config, scmutil, util, error, formatter
>  from node import hex
>  
>  samplehgrcs = {
> @@ -85,8 +85,9 @@ class ui(object):
>          self._ucfg = config.config() # untrusted
>          self._trustusers = set()
>          self._trustgroups = set()
>          self.callhooks = True
> +        self.paths = paths(self)
>  
>          if src:
>              self.fout = src.fout
>              self.ferr = src.ferr
> @@ -530,12 +531,13 @@ class ui(object):
>          """Return repository location relative to cwd or from [paths]"""
>          if util.hasscheme(loc) or os.path.isdir(os.path.join(loc, '.hg')):
>              return loc
>  
> -        path = self.config('paths', loc)
> -        if not path and default is not None:
> -            path = self.config('paths', default)
> -        return path or loc
> +        p = self.paths.getpath(loc, default=default)
> +        if p:
> +            return p.url
> +        else:
> +            return loc

Minor nit: we usually write this as:

if p:
    return p.url
return loc

>      def pushbuffer(self, error=False):
>          """install a buffer to capture standard output of the ui object
>  
> @@ -922,4 +924,39 @@ class ui(object):
>          ui.write(s, 'label') is equivalent to
>          ui.write(ui.label(s, 'label')).
>          '''
>          return msg
> +
> +class paths(object):
> +    """Represents a collection of paths and their configs.
> +
> +    Data is derived from ui instances and the config files they have loaded.
> +    """
> +    def __init__(self, ui):
> +        self._uiref = weakref.ref(ui)
> +
> +    @property
> +    def ui(self):
> +        return self._uiref()
> +
> +    def getpath(self, name, default=None):
> +        """Return a ``path`` for the specified name.
> +
> +        Returns None if the specified path or the default path was not
> +        found.
> +        """
> +        p = self.ui.config('paths', name)
> +        if not p and default is not None:
> +            p = self.ui.config('paths', default)
> +
> +        if p:
> +            return path(name, url=p)
> +        else:
> +            return None

Same here.