IPython/core/application.py

#!/usr/bin/env python
# encoding: utf-8
"""
An application for IPython.

All top-level applications should use the classes in this module for
handling configuration and creating componenets.

The job of an :class:`Application` is to create the master configuration 
object and then create the components, passing the config to them.

Authors:

* Brian Granger
* Fernando Perez

Notes
-----
"""

#-----------------------------------------------------------------------------
#  Copyright (C) 2008-2009  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 sys

from IPython.core import release
from IPython.utils.genutils import get_ipython_dir
from IPython.config.loader import (
    PyFileConfigLoader,
    ArgParseConfigLoader,
    Config,
    NoConfigDefault
)

#-----------------------------------------------------------------------------
# Classes and functions
#-----------------------------------------------------------------------------


class BaseAppArgParseConfigLoader(ArgParseConfigLoader):
    """Default command line options for IPython based applications."""

    def _add_other_arguments(self):
        self.parser.add_argument('--ipython-dir', 
            dest='Global.ipython_dir',type=unicode,
            help='Set to override default location of Global.ipython_dir.',
            default=NoConfigDefault,
            metavar='Global.ipython_dir')
        self.parser.add_argument('-p', '--profile',
            dest='Global.profile',type=unicode,
            help='The string name of the ipython profile to be used.',
            default=NoConfigDefault,
            metavar='Global.profile')
        self.parser.add_argument('--log-level',
            dest="Global.log_level",type=int,
            help='Set the log level (0,10,20,30,40,50).  Default is 30.',
            default=NoConfigDefault,
            metavar='Global.log_level')
        self.parser.add_argument('--config-file',
            dest='Global.config_file',type=unicode,
            help='Set the config file name to override default.',
            default=NoConfigDefault,
            metavar='Global.config_file')


class ApplicationError(Exception):
    pass


class Application(object):
    """Load a config, construct components and set them running."""

    name = u'ipython'
    description = 'IPython: an enhanced interactive Python shell.'
    config_file_name = u'ipython_config.py'
    default_log_level = logging.WARN

    def __init__(self):
        self._exiting = False
        self.init_logger()
        # Track the default and actual separately because some messages are
        # only printed if we aren't using the default.
        self.default_config_file_name = self.config_file_name

    def init_logger(self):
        self.log = logging.getLogger(self.__class__.__name__)
        # This is used as the default until the command line arguments are read.
        self.log.setLevel(self.default_log_level)
        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 _set_log_level(self, level):
        self.log.setLevel(level)

    def _get_log_level(self):
        return self.log.level

    log_level = property(_get_log_level, _set_log_level)

    def start(self):
        """Start the application."""
        self.attempt(self.create_default_config)
        self.log_default_config()
        self.set_default_config_log_level()
        self.attempt(self.pre_load_command_line_config)
        self.attempt(self.load_command_line_config, action='abort')
        self.set_command_line_config_log_level()
        self.attempt(self.post_load_command_line_config)
        self.log_command_line_config()
        self.attempt(self.find_ipython_dir)
        self.attempt(self.find_resources)
        self.attempt(self.find_config_file_name)
        self.attempt(self.find_config_file_paths)
        self.attempt(self.pre_load_file_config)
        self.attempt(self.load_file_config)
        self.set_file_config_log_level()
        self.attempt(self.post_load_file_config)
        self.log_file_config()
        self.attempt(self.merge_configs)
        self.log_master_config()
        self.attempt(self.pre_construct)
        self.attempt(self.construct)
        self.attempt(self.post_construct)
        self.attempt(self.start_app)

    #-------------------------------------------------------------------------
    # Various stages of Application creation
    #-------------------------------------------------------------------------

    def create_default_config(self):
        """Create defaults that can't be set elsewhere.

        For the most part, we try to set default in the class attributes
        of Components.  But, defaults the top-level Application (which is
        not a HasTraitlets or Component) are not set in this way.  Instead
        we set them here.  The Global section is for variables like this that
        don't belong to a particular component.
        """
        self.default_config = Config()
        self.default_config.Global.ipython_dir = get_ipython_dir()
        self.default_config.Global.log_level = self.log_level

    def log_default_config(self):
        self.log.debug('Default config loaded:')
        self.log.debug(repr(self.default_config))

    def set_default_config_log_level(self):
        try:
            self.log_level = self.default_config.Global.log_level
        except AttributeError:
            # Fallback to the default_log_level class attribute
            pass

    def create_command_line_config(self):
        """Create and return a command line config loader."""
        return BaseAppArgParseConfigLoader(
            description=self.description, 
            version=release.version
        )

    def pre_load_command_line_config(self):
        """Do actions just before loading the command line config."""
        pass

    def load_command_line_config(self):
        """Load the command line config."""
        loader = self.create_command_line_config()
        self.command_line_config = loader.load_config()
        self.extra_args = loader.get_extra_args()

    def set_command_line_config_log_level(self):
        try:
            self.log_level = self.command_line_config.Global.log_level
        except AttributeError:
            pass

    def post_load_command_line_config(self):
        """Do actions just after loading the command line config."""
        pass

    def log_command_line_config(self):
        self.log.debug("Command line config loaded:")
        self.log.debug(repr(self.command_line_config))

    def find_ipython_dir(self):
        """Set the IPython directory.

        This sets ``self.ipython_dir``, but the actual value that is passed
        to the application is kept in either ``self.default_config`` or
        ``self.command_line_config``.  This also adds ``self.ipython_dir`` to
        ``sys.path`` so config files there can be references by other config
        files.
        """

        try:
            self.ipython_dir = self.command_line_config.Global.ipython_dir
        except AttributeError:
            self.ipython_dir = self.default_config.Global.ipython_dir
        sys.path.append(os.path.abspath(self.ipython_dir))
        if not os.path.isdir(self.ipython_dir):
            os.makedirs(self.ipython_dir, mode=0777)
        self.log.debug("IPYTHON_DIR set to: %s" % self.ipython_dir)

    def find_resources(self):
        """Find other resources that need to be in place.

        Things like cluster directories need to be in place to find the
        config file.  These happen right after the IPython directory has
        been set.
        """
        pass

    def find_config_file_name(self):
        """Find the config file name for this application.

        This must set ``self.config_file_name`` to the filename of the
        config file to use (just the filename). The search paths for the
        config file are set in :meth:`find_config_file_paths` and then passed
        to the config file loader where they are resolved to an absolute path.

        If a profile has been set at the command line, this will resolve
        it.
        """

        try:
            self.config_file_name = self.command_line_config.Global.config_file
        except AttributeError:
            pass

        try:
            self.profile_name = self.command_line_config.Global.profile
            name_parts = self.config_file_name.split('.')
            name_parts.insert(1, u'_' + self.profile_name + u'.')
            self.config_file_name = ''.join(name_parts)
        except AttributeError:
            pass

    def find_config_file_paths(self):
        """Set the search paths for resolving the config file.

        This must set ``self.config_file_paths`` to a sequence of search
        paths to pass to the config file loader.
        """
        self.config_file_paths = (os.getcwd(), self.ipython_dir)

    def pre_load_file_config(self):
        """Do actions before the config file is loaded."""
        pass

    def load_file_config(self):
        """Load the config file.
        
        This tries to load the config file from disk.  If successful, the
        ``CONFIG_FILE`` config variable is set to the resolved config file
        location.  If not successful, an empty config is used.
        """
        self.log.debug("Attempting to load config file: %s" % self.config_file_name)
        loader = PyFileConfigLoader(self.config_file_name,
                                    path=self.config_file_paths)
        try:
            self.file_config = loader.load_config()
            self.file_config.Global.config_file = loader.full_filename
        except IOError:
            # Only warn if the default config file was NOT being used.
            if not self.config_file_name==self.default_config_file_name:
                self.log.warn("Config file not found, skipping: %s" % \
                               self.config_file_name, exc_info=True)
            self.file_config = Config()
        except:
            self.log.warn("Error loading config file: %s" % \
                          self.config_file_name, exc_info=True)
            self.file_config = Config()

    def set_file_config_log_level(self):
        # We need to keeep self.log_level updated.  But we only use the value
        # of the file_config if a value was not specified at the command
        # line, because the command line overrides everything.
        if not hasattr(self.command_line_config.Global, 'log_level'):
            try:
                self.log_level = self.file_config.Global.log_level
            except AttributeError:
                pass # Use existing value

    def post_load_file_config(self):
        """Do actions after the config file is loaded."""
        pass

    def log_file_config(self):
        if hasattr(self.file_config.Global, 'config_file'):
            self.log.debug("Config file loaded: %s" % self.file_config.Global.config_file)
            self.log.debug(repr(self.file_config))

    def merge_configs(self):
        """Merge the default, command line and file config objects."""
        config = Config()
        config._merge(self.default_config)
        config._merge(self.file_config)
        config._merge(self.command_line_config)
        self.master_config = config

    def log_master_config(self):
        self.log.debug("Master config created:")
        self.log.debug(repr(self.master_config))

    def pre_construct(self):
        """Do actions after the config has been built, but before construct."""
        pass

    def construct(self):
        """Construct the main components that make up this app."""
        self.log.debug("Constructing components for application")

    def post_construct(self):
        """Do actions after construct, but before starting the app."""
        pass

    def start_app(self):
        """Actually start the app."""
        self.log.debug("Starting application")

    #-------------------------------------------------------------------------
    # Utility methods
    #-------------------------------------------------------------------------

    def abort(self):
        """Abort the starting of the application."""
        if self._exiting:
            pass
        else:
            self.log.critical("Aborting application: %s" % self.name, exc_info=True)
            self._exiting = True
            sys.exit(1)

    def exit(self, exit_status=0):
        if self._exiting:
            pass
        else:
            self.log.debug("Exiting application: %s" % self.name)
            self._exiting = True
            sys.exit(exit_status)

    def attempt(self, func, action='abort'):
        try:
            func()
        except SystemExit:
            raise
        except:
            if action == 'abort':
                self.abort()
            elif action == 'exit':
                self.exit(0)