167 lines
4.6 KiB
Python
167 lines
4.6 KiB
Python
import pkg_resources
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import argparse
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import logging
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import sys
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from warnings import warn
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import six
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log = logging.getLogger(__name__)
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class HelpfulArgumentParser(argparse.ArgumentParser):
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def error(self, message): # pragma: nocover
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"""error(message: string)
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Prints a usage message incorporating the message to stderr and
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exits.
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If you override this in a subclass, it should not return -- it
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should either exit or raise an exception.
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"""
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self.print_help(sys.stderr)
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self._print_message('\n')
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self.exit(2, '%s: %s\n' % (self.prog, message))
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class CommandManager(object):
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""" Used to discover `pecan.command` entry points. """
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def __init__(self):
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self.commands = {}
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self.load_commands()
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def load_commands(self):
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for ep in pkg_resources.iter_entry_points('pecan.command'):
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log.debug('%s loading plugin %s', self.__class__.__name__, ep)
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if ep.name in self.commands:
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warn(
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"Duplicate entry points found on `%s` - ignoring %s" % (
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ep.name,
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ep
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),
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RuntimeWarning
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)
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continue
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try:
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cmd = ep.load()
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assert hasattr(cmd, 'run')
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except Exception as e: # pragma: nocover
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warn("Unable to load plugin %s: %s" % (ep, e), RuntimeWarning)
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continue
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self.add({ep.name: cmd})
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def add(self, cmd):
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self.commands.update(cmd)
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class CommandRunner(object):
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""" Dispatches `pecan` command execution requests. """
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def __init__(self):
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self.manager = CommandManager()
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self.parser = HelpfulArgumentParser(add_help=True)
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self.parser.add_argument(
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'--version',
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action='version',
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version='Pecan %s' % self.version
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)
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self.parse_sub_commands()
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def parse_sub_commands(self):
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subparsers = self.parser.add_subparsers(
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dest='command_name',
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metavar='command'
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)
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for name, cmd in self.commands.items():
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sub = subparsers.add_parser(
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name,
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help=cmd.summary
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)
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for arg in getattr(cmd, 'arguments', tuple()):
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arg = arg.copy()
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if isinstance(arg.get('name'), six.string_types):
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sub.add_argument(arg.pop('name'), **arg)
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elif isinstance(arg.get('name'), list):
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sub.add_argument(*arg.pop('name'), **arg)
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def run(self, args):
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ns = self.parser.parse_args(args)
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self.commands[ns.command_name]().run(ns)
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@classmethod
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def handle_command_line(cls): # pragma: nocover
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runner = CommandRunner()
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runner.run(sys.argv[1:])
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@property
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def version(self):
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return pkg_resources.get_distribution('pecan').version
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@property
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def commands(self):
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return self.manager.commands
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class BaseCommandMeta(type):
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@property
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def summary(cls):
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"""
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This is used to populate the --help argument on the command line.
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This provides a default behavior which takes the first sentence of the
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command's docstring and uses it.
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"""
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return cls.__doc__.strip().splitlines()[0].rstrip('.')
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class BaseCommandParent(object):
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"""
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A base interface for Pecan commands.
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Can be extended to support ``pecan`` command extensions in individual Pecan
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projects, e.g.,
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$ ``pecan my-custom-command config.py``
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::
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# myapp/myapp/custom_command.py
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class CustomCommand(pecan.commands.base.BaseCommand):
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'''
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(First) line of the docstring is used to summarize the command.
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'''
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arguments = ({
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'name': '--extra_arg',
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'help': 'an extra command line argument',
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'optional': True
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})
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def run(self, args):
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super(SomeCommand, self).run(args)
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if args.extra_arg:
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pass
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"""
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arguments = ({
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'name': 'config_file',
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'help': 'a Pecan configuration file',
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'nargs': '?',
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'default': None,
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},)
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def run(self, args):
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"""To be implemented by subclasses."""
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self.args = args
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def load_app(self):
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from pecan import load_app
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return load_app(self.args.config_file)
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BaseCommand = BaseCommandMeta('BaseCommand', (BaseCommandParent,), {
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'__doc__': BaseCommandParent.__doc__
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})
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