don't crash on bad config files

IPython/config/application.py

@@ -1,421 +1,426 b''
 # encoding: utf-8
 """
 A base class for a configurable application.
 
 Authors:
 
 * Brian Granger
 * Min RK
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import logging
 import os
 import re
 import sys
 from copy import deepcopy
 
 from IPython.config.configurable import SingletonConfigurable
 from IPython.config.loader import (
     KeyValueConfigLoader, PyFileConfigLoader, Config, ArgumentError
 )
 
 from IPython.utils.traitlets import (
     Unicode, List, Int, Enum, Dict, Instance, TraitError
 )
 from IPython.utils.importstring import import_item
 from IPython.utils.text import indent, wrap_paragraphs, dedent
 
 #-----------------------------------------------------------------------------
 # function for re-wrapping a helpstring
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Descriptions for the various sections
 #-----------------------------------------------------------------------------
 
 # merge flags&aliases into options
 option_description = """
 IPython command-line arguments are passed as '--<flag>', or '--<name>=<value>'.
 
 Arguments that take values are actually convenience aliases to full
 Configurables, whose aliases are listed on the help line. For more information
 on full configurables, see '--help-all'.
 """.strip() # trim newlines of front and back
 
 keyvalue_description = """
 Parameters are set from command-line arguments of the form:
 `--Class.trait=value`.
 This line is evaluated in Python, so simple expressions are allowed, e.g.::
 `--C.a='range(3)'` For setting C.a=[0,1,2].
 """.strip() # trim newlines of front and back
 
 subcommand_description = """
 Subcommands are launched as `{app} cmd [args]`. For information on using
 subcommand 'cmd', do: `{app} cmd -h`.
 """.strip().format(app=os.path.basename(sys.argv[0]))
 # get running program name
 
 #-----------------------------------------------------------------------------
 # Application class
 #-----------------------------------------------------------------------------
 
 
 class ApplicationError(Exception):
     pass
 
 
 class Application(SingletonConfigurable):
     """A singleton application with full configuration support."""
 
     # The name of the application, will usually match the name of the command
     # line application
     name = Unicode(u'application')
 
     # The description of the application that is printed at the beginning
     # of the help.
     description = Unicode(u'This is an application.')
     # default section descriptions
     option_description = Unicode(option_description)
     keyvalue_description = Unicode(keyvalue_description)
     subcommand_description = Unicode(subcommand_description)
 
     # The usage and example string that goes at the end of the help string.
     examples = Unicode()
 
     # A sequence of Configurable subclasses whose config=True attributes will
     # be exposed at the command line.
     classes = List([])
 
     # The version string of this application.
     version = Unicode(u'0.0')
 
     # The log level for the application
     log_level = Enum((0,10,20,30,40,50,'DEBUG','INFO','WARN','ERROR','CRITICAL'),
                     default_value=logging.WARN,
                     config=True,
                     help="Set the log level by value or name.")
     def _log_level_changed(self, name, old, new):
         """Adjust the log level when log_level is set."""
         if isinstance(new, basestring):
             new = getattr(logging, new)
             self.log_level = new
         self.log.setLevel(new)
     
     # the alias map for configurables
     aliases = Dict({'log-level' : 'Application.log_level'})
     
     # flags for loading Configurables or store_const style flags
     # flags are loaded from this dict by '--key' flags
     # this must be a dict of two-tuples, the first element being the Config/dict
     # and the second being the help string for the flag
     flags = Dict()
     def _flags_changed(self, name, old, new):
         """ensure flags dict is valid"""
         for key,value in new.iteritems():
             assert len(value) == 2, "Bad flag: %r:%s"%(key,value)
             assert isinstance(value[0], (dict, Config)), "Bad flag: %r:%s"%(key,value)
             assert isinstance(value[1], basestring), "Bad flag: %r:%s"%(key,value)
         
     
     # subcommands for launching other applications
     # if this is not empty, this will be a parent Application
     # this must be a dict of two-tuples, 
     # the first element being the application class/import string
     # and the second being the help string for the subcommand
     subcommands = Dict()
     # parse_command_line will initialize a subapp, if requested
     subapp = Instance('IPython.config.application.Application', allow_none=True)
     
     # extra command-line arguments that don't set config values
     extra_args = List(Unicode)
     
 
     def __init__(self, **kwargs):
         SingletonConfigurable.__init__(self, **kwargs)
         # Add my class to self.classes so my attributes appear in command line
         # options.
         self.classes.insert(0, self.__class__)
         
         self.init_logging()
 
     def _config_changed(self, name, old, new):
         SingletonConfigurable._config_changed(self, name, old, new)
         self.log.debug('Config changed:')
         self.log.debug(repr(new))
 
     def init_logging(self):
         """Start logging for this application.
 
         The default is to log to stdout using a StreaHandler. The log level
         starts at loggin.WARN, but this can be adjusted by setting the 
         ``log_level`` attribute.
         """
         self.log = logging.getLogger(self.__class__.__name__)
         self.log.setLevel(self.log_level)
         if sys.executable.endswith('pythonw.exe'):
             # this should really go to a file, but file-logging is only
             # hooked up in parallel applications
             self._log_handler = logging.StreamHandler(open(os.devnull, 'w'))
         else:
             self._log_handler = logging.StreamHandler()
         self._log_formatter = logging.Formatter("[%(name)s] %(message)s")
         self._log_handler.setFormatter(self._log_formatter)
         self.log.addHandler(self._log_handler)
 
     def initialize(self, argv=None):
         """Do the basic steps to configure me.
         
         Override in subclasses.
         """
         self.parse_command_line(argv)
         
     
     def start(self):
         """Start the app mainloop.
         
         Override in subclasses.
         """
         if self.subapp is not None:
             return self.subapp.start()
     
     def print_alias_help(self):
         """Print the alias part of the help."""
         if not self.aliases:
             return
         
         lines = []
         classdict = {}
         for cls in self.classes:
             # include all parents (up to, but excluding Configurable) in available names
             for c in cls.mro()[:-3]:
                 classdict[c.__name__] = c
         
         for alias, longname in self.aliases.iteritems():
             classname, traitname = longname.split('.',1)
             cls = classdict[classname]
             
             trait = cls.class_traits(config=True)[traitname]
             help = cls.class_get_trait_help(trait).splitlines()
             # reformat first line
             help[0] = help[0].replace(longname, alias) + ' (%s)'%longname
             lines.extend(help)
         # lines.append('')
         print os.linesep.join(lines)
     
     def print_flag_help(self):
         """Print the flag part of the help."""
         if not self.flags:
             return
         
         lines = []
         for m, (cfg,help) in self.flags.iteritems():
             lines.append('--'+m)
             lines.append(indent(dedent(help.strip())))
         # lines.append('')
         print os.linesep.join(lines)
     
     def print_options(self):
         if not self.flags and not self.aliases:
             return
         lines = ['Options']
         lines.append('-'*len(lines[0]))
         lines.append('')
         for p in wrap_paragraphs(self.option_description):
             lines.append(p)
             lines.append('')
         print os.linesep.join(lines)
         self.print_flag_help()
         self.print_alias_help()
         print
     
     def print_subcommands(self):
         """Print the subcommand part of the help."""
         if not self.subcommands:
             return
         
         lines = ["Subcommands"]
         lines.append('-'*len(lines[0]))
         lines.append('')
         for p in wrap_paragraphs(self.subcommand_description):
             lines.append(p)
             lines.append('')
         for subc, (cls, help) in self.subcommands.iteritems():
             lines.append(subc)
             if help:
                 lines.append(indent(dedent(help.strip())))
         lines.append('')
         print os.linesep.join(lines)
     
     def print_help(self, classes=False):
         """Print the help for each Configurable class in self.classes.
         
         If classes=False (the default), only flags and aliases are printed.
         """
         self.print_subcommands()
         self.print_options()
         
         if classes:
             if self.classes:
                 print "Class parameters"
                 print "----------------"
                 print
                 for p in wrap_paragraphs(self.keyvalue_description):
                     print p
                     print
         
             for cls in self.classes:
                 cls.class_print_help()
                 print
         else:
             print "To see all available configurables, use `--help-all`"
             print
 
     def print_description(self):
         """Print the application description."""
         for p in wrap_paragraphs(self.description):
             print p
             print
 
     def print_examples(self):
         """Print usage and examples.
 
         This usage string goes at the end of the command line help string
         and should contain examples of the application's usage.
         """
         if self.examples:
             print "Examples"
             print "--------"
             print
             print indent(dedent(self.examples.strip()))
             print
 
     def print_version(self):
         """Print the version string."""
         print self.version
 
     def update_config(self, config):
         """Fire the traits events when the config is updated."""
         # Save a copy of the current config.
         newconfig = deepcopy(self.config)
         # Merge the new config into the current one.
         newconfig._merge(config)
         # Save the combined config as self.config, which triggers the traits
         # events.
         self.config = newconfig
     
     def initialize_subcommand(self, subc, argv=None):
         """Initialize a subcommand with argv."""
         subapp,help = self.subcommands.get(subc)
         
         if isinstance(subapp, basestring):
             subapp = import_item(subapp)
         
         # clear existing instances
         self.__class__.clear_instance()
         # instantiate
         self.subapp = subapp.instance()
         # and initialize subapp
         self.subapp.initialize(argv)
         
     def parse_command_line(self, argv=None):
         """Parse the command line arguments."""
         argv = sys.argv[1:] if argv is None else argv
 
         if self.subcommands and len(argv) > 0:
             # we have subcommands, and one may have been specified
             subc, subargv = argv[0], argv[1:]
             if re.match(r'^\w(\-?\w)*$', subc) and subc in self.subcommands:
                 # it's a subcommand, and *not* a flag or class parameter
                 return self.initialize_subcommand(subc, subargv)
             
         if '-h' in argv or '--help' in argv or '--help-all' in argv:
             self.print_description()
             self.print_help('--help-all' in argv)
             self.print_examples()
             self.exit(0)
 
         if '--version' in argv:
             self.print_version()
             self.exit(0)
         
         loader = KeyValueConfigLoader(argv=argv, aliases=self.aliases,
                                         flags=self.flags)
         try:
             config = loader.load_config()
             self.update_config(config)
         except (TraitError, ArgumentError) as e:
             self.print_description()
             self.print_help()
             self.print_examples()
             self.log.fatal(str(e))
             self.exit(1)
         # store unparsed args in extra_args
         self.extra_args = loader.extra_args
 
     def load_config_file(self, filename, path=None):
         """Load a .py based config file by filename and path."""
         loader = PyFileConfigLoader(filename, path=path)
-        config = loader.load_config()
-        self.update_config(config)
+        try:
+            config = loader.load_config()
+        except Exception:
+            self.log.error("Exception while loading config file %s [path=%s]"%
+                            (filename, path), exc_info=True)
+        else:
+            self.update_config(config)
     
     def generate_config_file(self):
         """generate default config file from Configurables"""
         lines = ["# Configuration file for %s."%self.name]
         lines.append('')
         lines.append('c = get_config()')
         lines.append('')
         for cls in self.classes:
             lines.append(cls.class_config_section())
         return '\n'.join(lines)
 
     def exit(self, exit_status=0):
         self.log.debug("Exiting application: %s" % self.name)
         sys.exit(exit_status)
 
 #-----------------------------------------------------------------------------
 # utility functions, for convenience
 #-----------------------------------------------------------------------------
 
 def boolean_flag(name, configurable, set_help='', unset_help=''):
     """Helper for building basic --trait, --no-trait flags.
     
     Parameters
     ----------
     
     name : str
         The name of the flag.
     configurable : str
         The 'Class.trait' string of the trait to be set/unset with the flag
     set_help : unicode
         help string for --name flag
     unset_help : unicode
         help string for --no-name flag
     
     Returns
     -------
     
     cfg : dict
         A dict with two keys: 'name', and 'no-name', for setting and unsetting
         the trait, respectively.
     """
     # default helpstrings
     set_help = set_help or "set %s=True"%configurable
     unset_help = unset_help or "set %s=False"%configurable
     
     cls,trait = configurable.split('.')
     
     setter = {cls : {trait : True}}
     unsetter = {cls : {trait : False}}
     return {name : (setter, set_help), 'no-'+name : (unsetter, unset_help)}