ui: test plain mode against exceptions

Let ui.plain() accept an optional parameter in the form of a feature
name (as a string) to exclude from plain mode.

The result of ui.plain is now:
 - False if HGPLAIN is not set or the requested feature is in HGPLAINEXCEPT
 - True otherwise

Signed-off-by: "Yann E. MORIN" <[e-mail]>

mercurial/ui.py

@@ -1,698 +1,700 b''
 # ui.py - user interface bits for mercurial
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # 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 config, scmutil, util, error
 
 class ui(object):
     def __init__(self, src=None):
         self._buffers = []
         self.quiet = self.verbose = self.debugflag = self.tracebackflag = False
         self._reportuntrusted = True
         self._ocfg = config.config() # overlay
         self._tcfg = config.config() # trusted
         self._ucfg = config.config() # untrusted
         self._trustusers = set()
         self._trustgroups = set()
 
         if src:
             self._tcfg = src._tcfg.copy()
             self._ucfg = src._ucfg.copy()
             self._ocfg = src._ocfg.copy()
             self._trustusers = src._trustusers.copy()
             self._trustgroups = src._trustgroups.copy()
             self.environ = src.environ
             self.fixconfig()
         else:
             # shared read-only environment
             self.environ = os.environ
             # we always trust global config files
             for f in scmutil.rcpath():
                 self.readconfig(f, trust=True)
 
     def copy(self):
         return self.__class__(self)
 
     def _is_trusted(self, fp, f):
         st = util.fstat(fp)
         if util.isowner(st):
             return True
 
         tusers, tgroups = self._trustusers, self._trustgroups
         if '*' in tusers or '*' in tgroups:
             return True
 
         user = util.username(st.st_uid)
         group = util.groupname(st.st_gid)
         if user in tusers or group in tgroups or user == util.username():
             return True
 
         if self._reportuntrusted:
             self.warn(_('Not trusting file %s from untrusted '
                         'user %s, group %s\n') % (f, user, group))
         return False
 
     def readconfig(self, filename, root=None, trust=False,
                    sections=None, remap=None):
         try:
             fp = open(filename)
         except IOError:
             if not sections: # ignore unless we were looking for something
                 return
             raise
 
         cfg = config.config()
         trusted = sections or trust or self._is_trusted(fp, filename)
 
         try:
             cfg.read(filename, fp, sections=sections, remap=remap)
         except error.ConfigError, inst:
             if trusted:
                 raise
             self.warn(_("Ignored: %s\n") % str(inst))
 
         if self.plain():
             for k in ('debug', 'fallbackencoding', 'quiet', 'slash',
                       'logtemplate', 'style',
                       'traceback', 'verbose'):
                 if k in cfg['ui']:
                     del cfg['ui'][k]
             for k, v in cfg.items('alias'):
                 del cfg['alias'][k]
             for k, v in cfg.items('defaults'):
                 del cfg['defaults'][k]
 
         if trusted:
             self._tcfg.update(cfg)
             self._tcfg.update(self._ocfg)
         self._ucfg.update(cfg)
         self._ucfg.update(self._ocfg)
 
         if root is None:
             root = os.path.expanduser('~')
         self.fixconfig(root=root)
 
     def fixconfig(self, root=None, section=None):
         if section in (None, 'paths'):
             # expand vars and ~
             # translate paths relative to root (or home) into absolute paths
             root = root or os.getcwd()
             for c in self._tcfg, self._ucfg, self._ocfg:
                 for n, p in c.items('paths'):
                     if not p:
                         continue
                     if '%%' in p:
                         self.warn(_("(deprecated '%%' in path %s=%s from %s)\n")
                                   % (n, p, self.configsource('paths', n)))
                         p = p.replace('%%', '%')
                     p = util.expandpath(p)
                     if not util.hasscheme(p) and not os.path.isabs(p):
                         p = os.path.normpath(os.path.join(root, p))
                     c.set("paths", n, p)
 
         if section in (None, 'ui'):
             # update ui options
             self.debugflag = self.configbool('ui', 'debug')
             self.verbose = self.debugflag or self.configbool('ui', 'verbose')
             self.quiet = not self.debugflag and self.configbool('ui', 'quiet')
             if self.verbose and self.quiet:
                 self.quiet = self.verbose = False
             self._reportuntrusted = self.debugflag or self.configbool("ui",
                 "report_untrusted", True)
             self.tracebackflag = self.configbool('ui', 'traceback', False)
 
         if section in (None, 'trusted'):
             # update trust information
             self._trustusers.update(self.configlist('trusted', 'users'))
             self._trustgroups.update(self.configlist('trusted', 'groups'))
 
     def setconfig(self, section, name, value, overlay=True):
         if overlay:
             self._ocfg.set(section, name, value)
         self._tcfg.set(section, name, value)
         self._ucfg.set(section, name, value)
         self.fixconfig(section=section)
 
     def _data(self, untrusted):
         return untrusted and self._ucfg or self._tcfg
 
     def configsource(self, section, name, untrusted=False):
         return self._data(untrusted).source(section, name) or 'none'
 
     def config(self, section, name, default=None, untrusted=False):
         value = self._data(untrusted).get(section, name, default)
         if self.debugflag and not untrusted and self._reportuntrusted:
             uvalue = self._ucfg.get(section, name)
             if uvalue is not None and uvalue != value:
                 self.debug(_("ignoring untrusted configuration option "
                              "%s.%s = %s\n") % (section, name, uvalue))
         return value
 
     def configpath(self, section, name, default=None, untrusted=False):
         'get a path config item, expanded relative to config file'
         v = self.config(section, name, default, untrusted)
         if not os.path.isabs(v) or "://" not in v:
             src = self.configsource(section, name, untrusted)
             if ':' in src:
                 base = os.path.dirname(src.rsplit(':'))
                 v = os.path.join(base, os.path.expanduser(v))
         return v
 
     def configbool(self, section, name, default=False, untrusted=False):
         """parse a configuration element as a boolean
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'true', 'yes')
         >>> u.configbool(s, 'true')
         True
         >>> u.setconfig(s, 'false', 'no')
         >>> u.configbool(s, 'false')
         False
         >>> u.configbool(s, 'unknown')
         False
         >>> u.configbool(s, 'unknown', True)
         True
         >>> u.setconfig(s, 'invalid', 'somevalue')
         >>> u.configbool(s, 'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a boolean ('somevalue')
         """
 
         v = self.config(section, name, None, untrusted)
         if v is None:
             return default
         if isinstance(v, bool):
             return v
         b = util.parsebool(v)
         if b is None:
             raise error.ConfigError(_("%s.%s is not a boolean ('%s')")
                                     % (section, name, v))
         return b
 
     def configint(self, section, name, default=None, untrusted=False):
         """parse a configuration element as an integer
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'int1', '42')
         >>> u.configint(s, 'int1')
         42
         >>> u.setconfig(s, 'int2', '-42')
         >>> u.configint(s, 'int2')
         -42
         >>> u.configint(s, 'unknown', 7)
         7
         >>> u.setconfig(s, 'invalid', 'somevalue')
         >>> u.configint(s, 'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not an integer ('somevalue')
         """
 
         v = self.config(section, name, None, untrusted)
         if v is None:
             return default
         try:
             return int(v)
         except ValueError:
             raise error.ConfigError(_("%s.%s is not an integer ('%s')")
                                     % (section, name, v))
 
     def configlist(self, section, name, default=None, untrusted=False):
         """parse a configuration element as a list of comma/space separated
         strings
 
         >>> u = ui(); s = 'foo'
         >>> u.setconfig(s, 'list1', 'this,is "a small" ,test')
         >>> u.configlist(s, 'list1')
         ['this', 'is', 'a small', 'test']
         """
 
         def _parse_plain(parts, s, offset):
             whitespace = False
             while offset < len(s) and (s[offset].isspace() or s[offset] == ','):
                 whitespace = True
                 offset += 1
             if offset >= len(s):
                 return None, parts, offset
             if whitespace:
                 parts.append('')
             if s[offset] == '"' and not parts[-1]:
                 return _parse_quote, parts, offset + 1
             elif s[offset] == '"' and parts[-1][-1] == '\\':
                 parts[-1] = parts[-1][:-1] + s[offset]
                 return _parse_plain, parts, offset + 1
             parts[-1] += s[offset]
             return _parse_plain, parts, offset + 1
 
         def _parse_quote(parts, s, offset):
             if offset < len(s) and s[offset] == '"': # ""
                 parts.append('')
                 offset += 1
                 while offset < len(s) and (s[offset].isspace() or
                         s[offset] == ','):
                     offset += 1
                 return _parse_plain, parts, offset
 
             while offset < len(s) and s[offset] != '"':
                 if (s[offset] == '\\' and offset + 1 < len(s)
                         and s[offset + 1] == '"'):
                     offset += 1
                     parts[-1] += '"'
                 else:
                     parts[-1] += s[offset]
                 offset += 1
 
             if offset >= len(s):
                 real_parts = _configlist(parts[-1])
                 if not real_parts:
                     parts[-1] = '"'
                 else:
                     real_parts[0] = '"' + real_parts[0]
                     parts = parts[:-1]
                     parts.extend(real_parts)
                 return None, parts, offset
 
             offset += 1
             while offset < len(s) and s[offset] in [' ', ',']:
                 offset += 1
 
             if offset < len(s):
                 if offset + 1 == len(s) and s[offset] == '"':
                     parts[-1] += '"'
                     offset += 1
                 else:
                     parts.append('')
             else:
                 return None, parts, offset
 
             return _parse_plain, parts, offset
 
         def _configlist(s):
             s = s.rstrip(' ,')
             if not s:
                 return []
             parser, parts, offset = _parse_plain, [''], 0
             while parser:
                 parser, parts, offset = parser(parts, s, offset)
             return parts
 
         result = self.config(section, name, untrusted=untrusted)
         if result is None:
             result = default or []
         if isinstance(result, basestring):
             result = _configlist(result.lstrip(' ,\n'))
             if result is None:
                 result = default or []
         return result
 
     def has_section(self, section, untrusted=False):
         '''tell whether section exists in config.'''
         return section in self._data(untrusted)
 
     def configitems(self, section, untrusted=False):
         items = self._data(untrusted).items(section)
         if self.debugflag and not untrusted and self._reportuntrusted:
             for k, v in self._ucfg.items(section):
                 if self._tcfg.get(section, k) != v:
                     self.debug(_("ignoring untrusted configuration option "
                                 "%s.%s = %s\n") % (section, k, v))
         return items
 
     def walkconfig(self, untrusted=False):
         cfg = self._data(untrusted)
         for section in cfg.sections():
             for name, value in self.configitems(section, untrusted):
                 yield section, name, value
 
-    def plain(self):
+    def plain(self, feature=None):
         '''is plain mode active?
 
         Plain mode means that all configuration variables which affect
         the behavior and output of Mercurial should be
         ignored. Additionally, the output should be stable,
         reproducible and suitable for use in scripts or applications.
 
         The only way to trigger plain mode is by setting either the
         `HGPLAIN' or `HGPLAINEXCEPT' environment variables.
 
-        The return value can either be False, True, or a list of
-        features that plain mode should not apply to (e.g., i18n,
-        progress, etc).
+        The return value can either be
+        - False if HGPLAIN is not set, or feature is in HGPLAINEXCEPT
+        - True otherwise
         '''
         if 'HGPLAIN' not in os.environ and 'HGPLAINEXCEPT' not in os.environ:
             return False
         exceptions = os.environ.get('HGPLAINEXCEPT', '').strip().split(',')
-        return exceptions or True
+        if feature and exceptions:
+            return feature not in exceptions
+        return True
 
     def username(self):
         """Return default username to be used in commits.
 
         Searched in this order: $HGUSER, [ui] section of hgrcs, $EMAIL
         and stop searching if one of these is set.
         If not found and ui.askusername is True, ask the user, else use
         ($LOGNAME or $USER or $LNAME or $USERNAME) + "@full.hostname".
         """
         user = os.environ.get("HGUSER")
         if user is None:
             user = self.config("ui", "username")
             if user is not None:
                 user = os.path.expandvars(user)
         if user is None:
             user = os.environ.get("EMAIL")
         if user is None and self.configbool("ui", "askusername"):
             user = self.prompt(_("enter a commit username:"), default=None)
         if user is None and not self.interactive():
             try:
                 user = '%s@%s' % (util.getuser(), socket.getfqdn())
                 self.warn(_("No username found, using '%s' instead\n") % user)
             except KeyError:
                 pass
         if not user:
             raise util.Abort(_('no username supplied (see "hg help config")'))
         if "\n" in user:
             raise util.Abort(_("username %s contains a newline\n") % repr(user))
         return user
 
     def shortuser(self, user):
         """Return a short representation of a user name or email address."""
         if not self.verbose:
             user = util.shortuser(user)
         return user
 
     def expandpath(self, loc, default=None):
         """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
 
     def pushbuffer(self):
         self._buffers.append([])
 
     def popbuffer(self, labeled=False):
         '''pop the last buffer and return the buffered output
 
         If labeled is True, any labels associated with buffered
         output will be handled. By default, this has no effect
         on the output returned, but extensions and GUI tools may
         handle this argument and returned styled output. If output
         is being buffered so it can be captured and parsed or
         processed, labeled should not be set to True.
         '''
         return "".join(self._buffers.pop())
 
     def write(self, *args, **opts):
         '''write args to output
 
         By default, this method simply writes to the buffer or stdout,
         but extensions or GUI tools may override this method,
         write_err(), popbuffer(), and label() to style output from
         various parts of hg.
 
         An optional keyword argument, "label", can be passed in.
         This should be a string containing label names separated by
         space. Label names take the form of "topic.type". For example,
         ui.debug() issues a label of "ui.debug".
 
         When labeling output for a specific command, a label of
         "cmdname.type" is recommended. For example, status issues
         a label of "status.modified" for modified files.
         '''
         if self._buffers:
             self._buffers[-1].extend([str(a) for a in args])
         else:
             for a in args:
                 sys.stdout.write(str(a))
 
     def write_err(self, *args, **opts):
         try:
             if not getattr(sys.stdout, 'closed', False):
                 sys.stdout.flush()
             for a in args:
                 sys.stderr.write(str(a))
             # stderr may be buffered under win32 when redirected to files,
             # including stdout.
             if not getattr(sys.stderr, 'closed', False):
                 sys.stderr.flush()
         except IOError, inst:
             if inst.errno not in (errno.EPIPE, errno.EIO):
                 raise
 
     def flush(self):
         try: sys.stdout.flush()
         except: pass
         try: sys.stderr.flush()
         except: pass
 
     def interactive(self):
         '''is interactive input allowed?
 
         An interactive session is a session where input can be reasonably read
         from `sys.stdin'. If this function returns false, any attempt to read
         from stdin should fail with an error, unless a sensible default has been
         specified.
 
         Interactiveness is triggered by the value of the `ui.interactive'
         configuration variable or - if it is unset - when `sys.stdin' points
         to a terminal device.
 
         This function refers to input only; for output, see `ui.formatted()'.
         '''
         i = self.configbool("ui", "interactive", None)
         if i is None:
             try:
                 return sys.stdin.isatty()
             except AttributeError:
                 # some environments replace stdin without implementing isatty
                 # usually those are non-interactive
                 return False
 
         return i
 
     def termwidth(self):
         '''how wide is the terminal in columns?
         '''
         if 'COLUMNS' in os.environ:
             try:
                 return int(os.environ['COLUMNS'])
             except ValueError:
                 pass
         return util.termwidth()
 
     def formatted(self):
         '''should formatted output be used?
 
         It is often desirable to format the output to suite the output medium.
         Examples of this are truncating long lines or colorizing messages.
         However, this is not often not desirable when piping output into other
         utilities, e.g. `grep'.
 
         Formatted output is triggered by the value of the `ui.formatted'
         configuration variable or - if it is unset - when `sys.stdout' points
         to a terminal device. Please note that `ui.formatted' should be
         considered an implementation detail; it is not intended for use outside
         Mercurial or its extensions.
 
         This function refers to output only; for input, see `ui.interactive()'.
         This function always returns false when in plain mode, see `ui.plain()'.
         '''
         if self.plain():
             return False
 
         i = self.configbool("ui", "formatted", None)
         if i is None:
             try:
                 return sys.stdout.isatty()
             except AttributeError:
                 # some environments replace stdout without implementing isatty
                 # usually those are non-interactive
                 return False
 
         return i
 
     def _readline(self, prompt=''):
         if sys.stdin.isatty():
             try:
                 # magically add command line editing support, where
                 # available
                 import readline
                 # force demandimport to really load the module
                 readline.read_history_file
                 # windows sometimes raises something other than ImportError
             except Exception:
                 pass
         line = raw_input(prompt)
         # When stdin is in binary mode on Windows, it can cause
         # raw_input() to emit an extra trailing carriage return
         if os.linesep == '\r\n' and line and line[-1] == '\r':
             line = line[:-1]
         return line
 
     def prompt(self, msg, default="y"):
         """Prompt user with msg, read response.
         If ui is not interactive, the default is returned.
         """
         if not self.interactive():
             self.write(msg, ' ', default, "\n")
             return default
         try:
             r = self._readline(self.label(msg, 'ui.prompt') + ' ')
             if not r:
                 return default
             return r
         except EOFError:
             raise util.Abort(_('response expected'))
 
     def promptchoice(self, msg, choices, default=0):
         """Prompt user with msg, read response, and ensure it matches
         one of the provided choices. The index of the choice is returned.
         choices is a sequence of acceptable responses with the format:
         ('&None', 'E&xec', 'Sym&link') Responses are case insensitive.
         If ui is not interactive, the default is returned.
         """
         resps = [s[s.index('&')+1].lower() for s in choices]
         while True:
             r = self.prompt(msg, resps[default])
             if r.lower() in resps:
                 return resps.index(r.lower())
             self.write(_("unrecognized response\n"))
 
     def getpass(self, prompt=None, default=None):
         if not self.interactive():
             return default
         try:
             return getpass.getpass(prompt or _('password: '))
         except EOFError:
             raise util.Abort(_('response expected'))
     def status(self, *msg, **opts):
         '''write status message to output (if ui.quiet is False)
 
         This adds an output label of "ui.status".
         '''
         if not self.quiet:
             opts['label'] = opts.get('label', '') + ' ui.status'
             self.write(*msg, **opts)
     def warn(self, *msg, **opts):
         '''write warning message to output (stderr)
 
         This adds an output label of "ui.warning".
         '''
         opts['label'] = opts.get('label', '') + ' ui.warning'
         self.write_err(*msg, **opts)
     def note(self, *msg, **opts):
         '''write note to output (if ui.verbose is True)
 
         This adds an output label of "ui.note".
         '''
         if self.verbose:
             opts['label'] = opts.get('label', '') + ' ui.note'
             self.write(*msg, **opts)
     def debug(self, *msg, **opts):
         '''write debug message to output (if ui.debugflag is True)
 
         This adds an output label of "ui.debug".
         '''
         if self.debugflag:
             opts['label'] = opts.get('label', '') + ' ui.debug'
             self.write(*msg, **opts)
     def edit(self, text, user):
         (fd, name) = tempfile.mkstemp(prefix="hg-editor-", suffix=".txt",
                                       text=True)
         try:
             f = os.fdopen(fd, "w")
             f.write(text)
             f.close()
 
             editor = self.geteditor()
 
             util.system("%s \"%s\"" % (editor, name),
                         environ={'HGUSER': user},
                         onerr=util.Abort, errprefix=_("edit failed"))
 
             f = open(name)
             t = f.read()
             f.close()
         finally:
             os.unlink(name)
 
         return t
 
     def traceback(self, exc=None):
         '''print exception traceback if traceback printing enabled.
         only to call in exception handler. returns true if traceback
         printed.'''
         if self.tracebackflag:
             if exc:
                 traceback.print_exception(exc[0], exc[1], exc[2])
             else:
                 traceback.print_exc()
         return self.tracebackflag
 
     def geteditor(self):
         '''return editor to use'''
         return (os.environ.get("HGEDITOR") or
                 self.config("ui", "editor") or
                 os.environ.get("VISUAL") or
                 os.environ.get("EDITOR", "vi"))
 
     def progress(self, topic, pos, item="", unit="", total=None):
         '''show a progress message
 
         With stock hg, this is simply a debug message that is hidden
         by default, but with extensions or GUI tools it may be
         visible. 'topic' is the current operation, 'item' is a
         non-numeric marker of the current position (ie the currently
         in-process file), 'pos' is the current numeric position (ie
         revision, bytes, etc.), unit is a corresponding unit label,
         and total is the highest expected pos.
 
         Multiple nested topics may be active at a time.
 
         All topics should be marked closed by setting pos to None at
         termination.
         '''
 
         if pos is None or not self.debugflag:
             return
 
         if unit:
             unit = ' ' + unit
         if item:
             item = ' ' + item
 
         if total:
             pct = 100.0 * pos / total
             self.debug('%s:%s %s/%s%s (%4.2f%%)\n'
                      % (topic, item, pos, total, unit, pct))
         else:
             self.debug('%s:%s %s%s\n' % (topic, item, pos, unit))
 
     def log(self, service, message):
         '''hook for logging facility extensions
 
         service should be a readily-identifiable subsystem, which will
         allow filtering.
         message should be a newline-terminated string to log.
         '''
         pass
 
     def label(self, msg, label):
         '''style msg based on supplied label
 
         Like ui.write(), this just returns msg unchanged, but extensions
         and GUI tools can override it to allow styling output without
         writing it.
 
         ui.write(s, 'label') is equivalent to
         ui.write(ui.label(s, 'label')).
         '''
         return msg

tests/test-hgrc.t

@@ -1,171 +1,171 b''
 Use hgrc within $TESTTMP
 
   $ HGRCPATH=`pwd`/hgrc
   $ export HGRCPATH
 
 Basic syntax error
 
   $ echo "invalid" > $HGRCPATH
   $ hg version
   hg: parse error at $TESTTMP/hgrc:1: invalid
   [255]
   $ echo "" > $HGRCPATH
 
 Issue1199: Can't use '%' in hgrc (eg url encoded username)
 
   $ hg init "foo%bar"
   $ hg clone "foo%bar" foobar
   updating to branch default
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ cd foobar
   $ cat .hg/hgrc
   [paths]
   default = $TESTTMP/foo%bar
   $ hg paths
   default = $TESTTMP/foo%bar
   $ hg showconfig
   bundle.mainreporoot=$TESTTMP/foobar
   paths.default=$TESTTMP/foo%bar
   $ cd ..
 
 issue1829: wrong indentation
 
   $ echo '[foo]' > $HGRCPATH
   $ echo '  x = y' >> $HGRCPATH
   $ hg version
   hg: parse error at $TESTTMP/hgrc:2:   x = y
   [255]
 
   $ python -c "print '[foo]\nbar = a\n b\n c \n  de\n fg \nbaz = bif cb \n'" \
   > > $HGRCPATH
   $ hg showconfig foo
   foo.bar=a\nb\nc\nde\nfg
   foo.baz=bif cb
 
   $ FAKEPATH=/path/to/nowhere
   $ export FAKEPATH
   $ echo '%include $FAKEPATH/no-such-file' > $HGRCPATH
   $ hg version
   hg: parse error at $TESTTMP/hgrc:1: cannot include /path/to/nowhere/no-such-file (No such file or directory)
   [255]
   $ unset FAKEPATH
 
 username expansion
 
   $ olduser=$HGUSER
   $ unset HGUSER
 
   $ FAKEUSER='John Doe'
   $ export FAKEUSER
   $ echo '[ui]' > $HGRCPATH
   $ echo 'username = $FAKEUSER' >> $HGRCPATH
 
   $ hg init usertest
   $ cd usertest
   $ touch bar
   $ hg commit --addremove --quiet -m "added bar"
   $ hg log --template "{author}\n"
   John Doe
   $ cd ..
 
   $ hg showconfig
   ui.username=$FAKEUSER
 
   $ unset FAKEUSER
   $ HGUSER=$olduser
   $ export HGUSER
 
 showconfig with multiple arguments
 
   $ echo "[alias]" > $HGRCPATH
   $ echo "log = log -g" >> $HGRCPATH
   $ echo "[defaults]" >> $HGRCPATH
   $ echo "identify = -n" >> $HGRCPATH
   $ hg showconfig alias defaults
   alias.log=log -g
   defaults.identify=-n
   $ hg showconfig alias defaults.identify
   abort: only one config item permitted
   [255]
   $ hg showconfig alias.log defaults.identify
   abort: only one config item permitted
   [255]
 
 HGPLAIN
 
   $ cd ..
   $ p=`pwd`
   $ echo "[ui]" > $HGRCPATH
   $ echo "debug=true" >> $HGRCPATH
   $ echo "fallbackencoding=ASCII" >> $HGRCPATH
   $ echo "quiet=true" >> $HGRCPATH
   $ echo "slash=true" >> $HGRCPATH
   $ echo "traceback=true" >> $HGRCPATH
   $ echo "verbose=true" >> $HGRCPATH
   $ echo "style=~/.hgstyle" >> $HGRCPATH
   $ echo "logtemplate={node}" >> $HGRCPATH
   $ echo "[defaults]" >> $HGRCPATH
   $ echo "identify=-n" >> $HGRCPATH
   $ echo "[alias]" >> $HGRCPATH
   $ echo "log=log -g" >> $HGRCPATH
 
 customized hgrc
 
   $ hg showconfig
   read config from: $TESTTMP/hgrc
   $TESTTMP/hgrc:13: alias.log=log -g
   $TESTTMP/hgrc:11: defaults.identify=-n
   $TESTTMP/hgrc:2: ui.debug=true
   $TESTTMP/hgrc:3: ui.fallbackencoding=ASCII
   $TESTTMP/hgrc:4: ui.quiet=true
   $TESTTMP/hgrc:5: ui.slash=true
   $TESTTMP/hgrc:6: ui.traceback=true
   $TESTTMP/hgrc:7: ui.verbose=true
   $TESTTMP/hgrc:8: ui.style=~/.hgstyle
   $TESTTMP/hgrc:9: ui.logtemplate={node}
 
 plain hgrc
 
   $ HGPLAIN=; export HGPLAIN
   $ hg showconfig --config ui.traceback=True --debug
   read config from: $TESTTMP/hgrc
   none: ui.traceback=True
   none: ui.verbose=False
   none: ui.debug=True
   none: ui.quiet=False
 
 plain mode with exceptions
 
   $ cat > plain.py <<EOF
   > def uisetup(ui):
   >     ui.write('plain: %r\n' % ui.plain())
   > EOF
   $ echo "[extensions]" >> $HGRCPATH
   $ echo "plain=./plain.py" >> $HGRCPATH
   $ HGPLAINEXCEPT=; export HGPLAINEXCEPT
   $ hg showconfig --config ui.traceback=True --debug
-  plain: ['']
+  plain: True
   read config from: $TESTTMP/hgrc
   $TESTTMP/hgrc:15: extensions.plain=./plain.py
   none: ui.traceback=True
   none: ui.verbose=False
   none: ui.debug=True
   none: ui.quiet=False
   $ unset HGPLAIN
   $ hg showconfig --config ui.traceback=True --debug
-  plain: ['']
+  plain: True
   read config from: $TESTTMP/hgrc
   $TESTTMP/hgrc:15: extensions.plain=./plain.py
   none: ui.traceback=True
   none: ui.verbose=False
   none: ui.debug=True
   none: ui.quiet=False
   $ HGPLAINEXCEPT=i18n; export HGPLAINEXCEPT
   $ hg showconfig --config ui.traceback=True --debug
-  plain: ['i18n']
+  plain: True
   read config from: $TESTTMP/hgrc
   $TESTTMP/hgrc:15: extensions.plain=./plain.py
   none: ui.traceback=True
   none: ui.verbose=False
   none: ui.debug=True
   none: ui.quiet=False