# # Copyright © 2010—2023 Andrey Mikhaylenko and contributors # # This file is part of Argh. # # Argh is free software under terms of the GNU Lesser # General Public License version 3 (LGPLv3) as published by the Free # Software Foundation. See the file README.rst for copying conditions. # """ Assembling ~~~~~~~~~~ Functions and classes to properly assemble your commands in a parser. """ import warnings from collections import OrderedDict from argh.completion import COMPLETION_ENABLED from argh.constants import ( ATTR_ALIASES, ATTR_ARGS, ATTR_EXPECTS_NAMESPACE_OBJECT, ATTR_NAME, DEFAULT_ARGUMENT_TEMPLATE, DEST_FUNCTION, PARSER_FORMATTER, ) from argh.exceptions import AssemblingError from argh.utils import get_arg_spec, get_subparsers __all__ = [ "SUPPORTS_ALIASES", "set_default_command", "add_commands", "add_subcommands", ] # TODO: remove in v.0.30. SUPPORTS_ALIASES = True """ .. deprecated:: 0.28.0 This constant will be removed in Argh v.0.30. It's not relevant anymore because it's always `True` for all Python versions currently supported by Argh. """ def _get_args_from_signature(function): if getattr(function, ATTR_EXPECTS_NAMESPACE_OBJECT, False): return spec = get_arg_spec(function) defaults = dict(zip(*[reversed(x) for x in (spec.args, spec.defaults or [])])) defaults.update(getattr(spec, "kwonlydefaults", None) or {}) kwonly = getattr(spec, "kwonlyargs", []) annotations = dict( (k, v) for k, v in function.__annotations__.items() if isinstance(v, str) ) # define the list of conflicting option strings # (short forms, i.e. single-character ones) chars = [a[0] for a in spec.args + kwonly] char_counts = dict((char, chars.count(char)) for char in set(chars)) conflicting_opts = tuple(char for char in char_counts if 1 < char_counts[char]) for name in spec.args + kwonly: flags = [] # name_or_flags akwargs = {} # keyword arguments for add_argument() # TODO: remove this in v.0.30. if name in annotations: # help message: func(a : "b") -> add_argument("a", help="b") value = annotations.get(name) if isinstance(value, str): warnings.warn( "Defining argument help messages via annotations is " + "deprecated and will be removed in Argh 0.30. Please " + 'replace `f(a:"foo")` with `@arg("-a", help="foo")(a)`.', DeprecationWarning, ) akwargs.update(help=value) if name in defaults or name in kwonly: if name in defaults: akwargs.update(default=defaults.get(name)) else: akwargs.update(required=True) flags = ("-{0}".format(name[0]), "--{0}".format(name)) if name.startswith(conflicting_opts): # remove short name flags = flags[1:] else: # positional argument flags = (name,) # cmd(foo_bar) -> add_argument('foo-bar') flags = tuple(x.replace("_", "-") if x.startswith("-") else x for x in flags) yield dict(option_strings=flags, **akwargs) if spec.varargs: # *args yield dict(option_strings=[spec.varargs], nargs="*") def _guess(kwargs): """ Adds types, actions, etc. to given argument specification. For example, ``default=3`` implies ``type=int``. :param arg: a :class:`argh.utils.Arg` instance """ guessed = {} # Parser actions that accept argument 'type' TYPE_AWARE_ACTIONS = "store", "append" # guess type/action from default value value = kwargs.get("default") if value is not None: if isinstance(value, bool): if kwargs.get("action") is None: # infer action from default value guessed["action"] = "store_false" if value else "store_true" elif kwargs.get("type") is None: # infer type from default value # (make sure that action handler supports this keyword) if kwargs.get("action", "store") in TYPE_AWARE_ACTIONS: guessed["type"] = type(value) # guess type from choices (first item) if kwargs.get("choices") and "type" not in list(guessed) + list(kwargs): guessed["type"] = type(kwargs["choices"][0]) return dict(kwargs, **guessed) def _is_positional(args, prefix_chars="-"): if not args or not args[0]: raise ValueError("Expected at least one argument") if args[0][0].startswith(tuple(prefix_chars)): return False else: return True def _get_parser_param_kwargs(parser, argspec): argspec = argspec.copy() # parser methods modify source data args = argspec["option_strings"] if _is_positional(args, prefix_chars=parser.prefix_chars): get_kwargs = parser._get_positional_kwargs else: get_kwargs = parser._get_optional_kwargs kwargs = get_kwargs(*args, **argspec) kwargs["dest"] = kwargs["dest"].replace("-", "_") return kwargs def _get_dest(parser, argspec): kwargs = _get_parser_param_kwargs(parser, argspec) return kwargs["dest"] def set_default_command(parser, function): """ Sets default command (i.e. a function) for given parser. If `parser.description` is empty and the function has a docstring, it is used as the description. .. note:: If there are both explicitly declared arguments (e.g. via :func:`~argh.decorators.arg`) and ones inferred from the function signature, declared ones will be merged into inferred ones. If an argument does not conform to the function signature, `AssemblingError` is raised. .. note:: If the parser was created with ``add_help=True`` (which is by default), option name ``-h`` is silently removed from any argument. """ spec = get_arg_spec(function) declared_args = getattr(function, ATTR_ARGS, []) inferred_args = list(_get_args_from_signature(function)) if inferred_args and declared_args: # We've got a mixture of declared and inferred arguments # a mapping of "dest" strings to argument declarations. # # * a "dest" string is a normalized form of argument name, i.e.: # # '-f', '--foo' → 'foo' # 'foo-bar' → 'foo_bar' # # * argument declaration is a dictionary representing an argument; # it is obtained either from _get_args_from_signature() or from # an @arg decorator (as is). # dests = OrderedDict() for argspec in inferred_args: dest = _get_parser_param_kwargs(parser, argspec)["dest"] dests[dest] = argspec for declared_kw in declared_args: # an argument is declared via decorator dest = _get_dest(parser, declared_kw) if dest in dests: # the argument is already known from function signature # # now make sure that this declared arg conforms to the function # signature and therefore only refines an inferred arg: # # @arg('my-foo') maps to func(my_foo) # @arg('--my-bar') maps to func(my_bar=...) # either both arguments are positional or both are optional decl_positional = _is_positional(declared_kw["option_strings"]) infr_positional = _is_positional(dests[dest]["option_strings"]) if decl_positional != infr_positional: kinds = {True: "positional", False: "optional"} raise AssemblingError( '{func}: argument "{dest}" declared as {kind_i} ' "(in function signature) and {kind_d} (via decorator)".format( func=function.__name__, dest=dest, kind_i=kinds[infr_positional], kind_d=kinds[decl_positional], ) ) # merge explicit argument declaration into the inferred one # (e.g. `help=...`) dests[dest].update(**declared_kw) else: # the argument is not in function signature varkw = getattr(spec, "varkw", getattr(spec, "keywords", [])) if varkw: # function accepts **kwargs; the argument goes into it dests[dest] = declared_kw else: # there's no way we can map the argument declaration # to function signature xs = (dests[x]["option_strings"] for x in dests) raise AssemblingError( "{func}: argument {flags} does not fit " "function signature: {sig}".format( flags=", ".join(declared_kw["option_strings"]), func=function.__name__, sig=", ".join("/".join(x) for x in xs), ) ) # pack the modified data back into a list inferred_args = dests.values() command_args = inferred_args or declared_args # add types, actions, etc. (e.g. default=3 implies type=int) command_args = [_guess(x) for x in command_args] for draft in command_args: draft = draft.copy() if "help" not in draft: draft.update(help=DEFAULT_ARGUMENT_TEMPLATE) dest_or_opt_strings = draft.pop("option_strings") if parser.add_help and "-h" in dest_or_opt_strings: dest_or_opt_strings = [x for x in dest_or_opt_strings if x != "-h"] completer = draft.pop("completer", None) try: action = parser.add_argument(*dest_or_opt_strings, **draft) if COMPLETION_ENABLED and completer: action.completer = completer except Exception as e: raise type(e)( "{func}: cannot add arg {args}: {msg}".format( args="/".join(dest_or_opt_strings), func=function.__name__, msg=e ) ) if function.__doc__ and not parser.description: parser.description = function.__doc__ parser.set_defaults( **{ DEST_FUNCTION: function, } ) def add_commands( parser, functions, namespace=None, namespace_kwargs=None, func_kwargs=None, # deprecated args: title=None, description=None, help=None, ): """ Adds given functions as commands to given parser. :param parser: an :class:`argparse.ArgumentParser` instance. :param functions: a list of functions. A subparser is created for each of them. If the function is decorated with :func:`~argh.decorators.arg`, the arguments are passed to :meth:`argparse.ArgumentParser.add_argument`. See also :func:`~argh.dispatching.dispatch` for requirements concerning function signatures. The command name is inferred from the function name. Note that the underscores in the name are replaced with hyphens, i.e. function name "foo_bar" becomes command name "foo-bar". :param namespace: an optional string representing the group of commands. For example, if a command named "hello" is added without the namespace, it will be available as "prog.py hello"; if the namespace if specified as "greet", then the command will be accessible as "prog.py greet hello". The namespace itself is not callable, so "prog.py greet" will fail and only display a help message. :param func_kwargs: a `dict` of keyword arguments to be passed to each nested ArgumentParser instance created per command (i.e. per function). Members of this dictionary have the highest priority, so a function's docstring is overridden by a `help` in `func_kwargs` (if present). :param namespace_kwargs: a `dict` of keyword arguments to be passed to the nested ArgumentParser instance under given `namespace`. Deprecated params that should be moved into `namespace_kwargs`: :param title: .. deprecated:: 0.26.0 This argument will be removed in Argh v.0.30. Please use `namespace_kwargs` instead. :param description: .. deprecated:: 0.26.0 This argument will be removed in Argh v.0.30. Please use `namespace_kwargs` instead. :param help: .. deprecated:: 0.26.0 This argument will be removed in Argh v.0.30. Please use `namespace_kwargs` instead. .. note:: This function modifies the parser object. Generally side effects are bad practice but we don't seem to have any choice as ArgumentParser is pretty opaque. You may prefer :meth:`~argh.helpers.ArghParser.add_commands` for a bit more predictable API. .. note:: An attempt to add commands to a parser which already has a default function (e.g. added with :func:`~argh.assembling.set_default_command`) results in `AssemblingError`. """ # FIXME "namespace" is a correct name but it clashes with the "namespace" # that represents arguments (argparse.Namespace and our ArghNamespace). # We should rename the argument here. namespace_kwargs = namespace_kwargs or {} # TODO remove this in 0.30 # if title: warnings.warn( "Argument `title` is deprecated in add_commands(), " + "it will be removed in Argh 0.30. " + "Please use `parser_kwargs` instead.", DeprecationWarning, ) namespace_kwargs["description"] = title if help: warnings.warn( "Argument `help` is deprecated in add_commands(), " + "it will be removed in Argh 0.30. " + "Please use `parser_kwargs` instead.", DeprecationWarning, ) namespace_kwargs["help"] = help if description: warnings.warn( "Argument `description` is deprecated in add_commands(), " + "it will be removed in Argh 0.30. " + "Please use `parser_kwargs` instead.", DeprecationWarning, ) namespace_kwargs["description"] = description # # / subparsers_action = get_subparsers(parser, create=True) if namespace: # Make a nested parser and init a deeper _SubParsersAction under it. # Create a named group of commands. It will be listed along with # root-level commands in ``app.py --help``; in that context its `title` # can be used as a short description on the right side of its name. # Normally `title` is shown above the list of commands # in ``app.py my-namespace --help``. subsubparser_kw = { "help": namespace_kwargs.get("title"), } subsubparser = subparsers_action.add_parser(namespace, **subsubparser_kw) subparsers_action = subsubparser.add_subparsers(**namespace_kwargs) else: if namespace_kwargs: raise ValueError("`parser_kwargs` only makes sense " "with `namespace`.") for func in functions: cmd_name, func_parser_kwargs = _extract_command_meta_from_func(func) # override any computed kwargs by manually supplied ones if func_kwargs: func_parser_kwargs.update(func_kwargs) # create and set up the parser for this command command_parser = subparsers_action.add_parser(cmd_name, **func_parser_kwargs) set_default_command(command_parser, func) def _extract_command_meta_from_func(func): # use explicitly defined name; if none, use function name (a_b → a-b) cmd_name = getattr(func, ATTR_NAME, func.__name__.replace("_", "-")) func_parser_kwargs = { # add command help from function's docstring "help": func.__doc__, # set default formatter "formatter_class": PARSER_FORMATTER, } # add aliases for command name func_parser_kwargs["aliases"] = getattr(func, ATTR_ALIASES, []) return cmd_name, func_parser_kwargs def add_subcommands(parser, namespace, functions, **namespace_kwargs): """ A wrapper for :func:`add_commands`. These examples are equivalent:: add_commands(parser, [get, put], namespace='db', namespace_kwargs={ 'title': 'database commands', 'help': 'CRUD for our silly database' }) add_subcommands(parser, 'db', [get, put], title='database commands', help='CRUD for our silly database') """ add_commands( parser, functions, namespace=namespace, namespace_kwargs=namespace_kwargs )