Source code for plumbum.cli.switches

import contextlib
import inspect
from abc import ABC, abstractmethod
from typing import Callable, Generator, List, Union

from plumbum import local
from plumbum.cli.i18n import get_translation_for
from plumbum.lib import getdoc

_translation = get_translation_for(__name__)
_, ngettext = _translation.gettext, _translation.ngettext

[docs]class SwitchError(Exception): """A general switch related-error (base class of all other switch errors)"""
[docs]class PositionalArgumentsError(SwitchError): """Raised when an invalid number of positional arguments has been given"""
[docs]class SwitchCombinationError(SwitchError): """Raised when an invalid combination of switches has been given"""
[docs]class UnknownSwitch(SwitchError): """Raised when an unrecognized switch has been given"""
[docs]class MissingArgument(SwitchError): """Raised when a switch requires an argument, but one was not provided"""
[docs]class MissingMandatorySwitch(SwitchError): """Raised when a mandatory switch has not been given"""
[docs]class WrongArgumentType(SwitchError): """Raised when a switch expected an argument of some type, but an argument of a wrong type has been given"""
[docs]class SubcommandError(SwitchError): """Raised when there's something wrong with sub-commands"""
# =================================================================================================== # The switch decorator # =================================================================================================== class SwitchInfo: def __init__(self, **kwargs): for k, v in kwargs.items(): setattr(self, k, v)
[docs]def switch( names, argtype=None, argname=None, list=False, # pylint: disable=redefined-builtin mandatory=False, requires=(), excludes=(), help=None, # pylint: disable=redefined-builtin overridable=False, group="Switches", envname=None, ): """ A decorator that exposes functions as command-line switches. Usage:: class MyApp(Application): @switch(["-l", "--log-to-file"], argtype = str) def log_to_file(self, filename): handler = logging.FileHandler(filename) logger.addHandler(handler) @switch(["--verbose"], excludes=["--terse"], requires=["--log-to-file"]) def set_debug(self): logger.setLevel(logging.DEBUG) @switch(["--terse"], excludes=["--verbose"], requires=["--log-to-file"]) def set_terse(self): logger.setLevel(logging.WARNING) :param names: The name(s) under which the function is reachable; it can be a string or a list of string, but at least one name is required. There's no need to prefix the name with ``-`` or ``--`` (this is added automatically), but it can be used for clarity. Single-letter names are prefixed by ``-``, while longer names are prefixed by ``--`` :param envname: Name of environment variable to extract value from, as alternative to argv :param argtype: If this function takes an argument, you need to specify its type. The default is ``None``, which means the function takes no argument. The type is more of a "validator" than a real type; it can be any callable object that raises a ``TypeError`` if the argument is invalid, or returns an appropriate value on success. If the user provides an invalid value, :func:`plumbum.cli.WrongArgumentType` :param argname: The name of the argument; if ``None``, the name will be inferred from the function's signature :param list: Whether or not this switch can be repeated (e.g. ``gcc -I/lib -I/usr/lib``). If ``False``, only a single occurrence of the switch is allowed; if ``True``, it may be repeated indefinitely. The occurrences are collected into a list, so the function is only called once with the collections. For instance, for ``gcc -I/lib -I/usr/lib``, the function will be called with ``["/lib", "/usr/lib"]``. :param mandatory: Whether or not this switch is mandatory; if a mandatory switch is not given, :class:`MissingMandatorySwitch <plumbum.cli.MissingMandatorySwitch>` is raised. The default is ``False``. :param requires: A list of switches that this switch depends on ("requires"). This means that it's invalid to invoke this switch without also invoking the required ones. In the example above, it's illegal to pass ``--verbose`` or ``--terse`` without also passing ``--log-to-file``. By default, this list is empty, which means the switch has no prerequisites. If an invalid combination is given, :class:`SwitchCombinationError <plumbum.cli.SwitchCombinationError>` is raised. Note that this list is made of the switch *names*; if a switch has more than a single name, any of its names will do. .. note:: There is no guarantee on the (topological) order in which the actual switch functions will be invoked, as the dependency graph might contain cycles. :param excludes: A list of switches that this switch forbids ("excludes"). This means that it's invalid to invoke this switch if any of the excluded ones are given. In the example above, it's illegal to pass ``--verbose`` along with ``--terse``, as it will result in a contradiction. By default, this list is empty, which means the switch has no prerequisites. If an invalid combination is given, :class:`SwitchCombinationError <plumbum.cli.SwitchCombinationError>` is raised. Note that this list is made of the switch *names*; if a switch has more than a single name, any of its names will do. :param help: The help message (description) for this switch; this description is used when ``--help`` is given. If ``None``, the function's docstring will be used. :param overridable: Whether or not the names of this switch are overridable by other switches. If ``False`` (the default), having another switch function with the same name(s) will cause an exception. If ``True``, this is silently ignored. :param group: The switch's *group*; this is a string that is used to group related switches together when ``--help`` is given. The default group is ``Switches``. :returns: The decorated function (with a ``_switch_info`` attribute) """ if isinstance(names, str): names = [names] names = [n.lstrip("-") for n in names] requires = [n.lstrip("-") for n in requires] excludes = [n.lstrip("-") for n in excludes] def deco(func): if argname is None: argspec = inspect.getfullargspec(func).args argname2 = argspec[1] if len(argspec) == 2 else _("VALUE") else: argname2 = argname help2 = getdoc(func) if help is None else help if not help2: help2 = str(func) func._switch_info = SwitchInfo( names=names, envname=envname, argtype=argtype, list=list, func=func, mandatory=mandatory, overridable=overridable, group=group, requires=requires, excludes=excludes, argname=argname2, help=help2, ) return func return deco
[docs]def autoswitch(*args, **kwargs): """A decorator that exposes a function as a switch, "inferring" the name of the switch from the function's name (converting to lower-case, and replacing underscores with hyphens). The arguments are the same as for :func:`switch <plumbum.cli.switch>`.""" def deco(func): return switch(func.__name__.replace("_", "-"), *args, **kwargs)(func) return deco
# =================================================================================================== # Switch Attributes # ===================================================================================================
[docs]class SwitchAttr: """ A switch that stores its result in an attribute (descriptor). Usage:: class MyApp(Application): logfile = SwitchAttr(["-f", "--log-file"], str) def main(self): if self.logfile: open(self.logfile, "w") :param names: The switch names :param argtype: The switch argument's (and attribute's) type :param default: The attribute's default value (``None``) :param argname: The switch argument's name (default is ``"VALUE"``) :param kwargs: Any of the keyword arguments accepted by :func:`switch <plumbum.cli.switch>` """ ATTR_NAME = "__plumbum_switchattr_dict__" VALUE = _("VALUE") def __init__( self, names, argtype=str, default=None, list=False, # pylint: disable=redefined-builtin argname=VALUE, **kwargs, ): # Setting to prevent the help message from showing SwitchAttr's docstring self.__doc__ = "Sets an attribute" if default and argtype is not None: defaultmsg = _("; the default is {0}").format(default) if "help" in kwargs: kwargs["help"] += defaultmsg else: kwargs["help"] = defaultmsg.lstrip("; ") switch(names, argtype=argtype, argname=argname, list=list, **kwargs)(self) listtype = type([]) if list: if default is None: self._default_value = [] elif isinstance(default, (tuple, listtype)): self._default_value = listtype(default) else: self._default_value = [default] else: self._default_value = default def __call__(self, inst, val): self.__set__(inst, val) def __get__(self, inst, cls): if inst is None: return self return getattr(inst, self.ATTR_NAME, {}).get(self, self._default_value) def __set__(self, inst, val): if inst is None: raise AttributeError("cannot set an unbound SwitchAttr") if not hasattr(inst, self.ATTR_NAME): setattr(inst, self.ATTR_NAME, {self: val}) else: getattr(inst, self.ATTR_NAME)[self] = val
[docs]class Flag(SwitchAttr): """A specialized :class:`SwitchAttr <plumbum.cli.SwitchAttr>` for boolean flags. If the flag is not given, the value of this attribute is ``default``; if it is given, the value changes to ``not default``. Usage:: class MyApp(Application): verbose = Flag(["-v", "--verbose"], help = "If given, I'll be very talkative") :param names: The switch names :param default: The attribute's initial value (``False`` by default) :param kwargs: Any of the keyword arguments accepted by :func:`switch <plumbum.cli.switch>`, except for ``list`` and ``argtype``. """ def __init__(self, names, default=False, **kwargs): SwitchAttr.__init__( self, names, argtype=None, default=default, list=False, **kwargs ) def __call__(self, inst): self.__set__(inst, not self._default_value)
[docs]class CountOf(SwitchAttr): """A specialized :class:`SwitchAttr <plumbum.cli.SwitchAttr>` that counts the number of occurrences of the switch in the command line. Usage:: class MyApp(Application): verbosity = CountOf(["-v", "--verbose"], help = "The more, the merrier") If ``-v -v -vv`` is given in the command-line, it will result in ``verbosity = 4``. :param names: The switch names :param default: The default value (0) :param kwargs: Any of the keyword arguments accepted by :func:`switch <plumbum.cli.switch>`, except for ``list`` and ``argtype``. """ def __init__(self, names, default=0, **kwargs): SwitchAttr.__init__( self, names, argtype=None, default=default, list=True, **kwargs ) self._default_value = default # issue #118 def __call__(self, inst, v): self.__set__(inst, len(v))
# =================================================================================================== # Decorator for function that adds argument checking # ===================================================================================================
[docs]class positional: """ Runs a validator on the main function for a class. This should be used like this:: class MyApp(cli.Application): @cli.positional(cli.Range(1,10), cli.ExistingFile) def main(self, x, *f): # x is a range, f's are all ExistingFile's) Or, Python 3 only:: class MyApp(cli.Application): def main(self, x : cli.Range(1,10), *f : cli.ExistingFile): # x is a range, f's are all ExistingFile's) If you do not want to validate on the annotations, use this decorator ( even if empty) to override annotation validation. Validators should be callable, and should have a ``.choices()`` function with possible choices. (For future argument completion, for example) Default arguments do not go through the validator. #TODO: Check with MyPy """ def __init__(self, *args, **kargs): self.args = args self.kargs = kargs def __call__(self, function): m = inspect.getfullargspec(function) args_names = list(m.args[1:]) positional_list = [None] * len(args_names) varargs = None for i in range(min(len(positional_list), len(self.args))): positional_list[i] = self.args[i] if len(args_names) + 1 == len(self.args): varargs = self.args[-1] # All args are positional, so convert kargs to positional for item, value in self.kargs.items(): if item == m.varargs: varargs = value else: positional_list[args_names.index(item)] = value function.positional = positional_list function.positional_varargs = varargs return function
[docs]class Validator(ABC): __slots__ = () @abstractmethod def __call__(self, obj): "Must be implemented for a Validator to work" # pylint: disable-next=no-self-use
[docs] def choices(self, partial=""): # noqa: ARG002 """Should return set of valid choices, can be given optional partial info""" return set()
def __repr__(self): """If not overridden, will print the slots as args""" slots = {} for cls in self.__mro__: for prop in getattr(cls, "__slots__", ()): if prop[0] != "_": slots[prop] = getattr(self, prop) mystrs = (f"{name} = {value}" for name, value in slots.items()) mystrs_str = ", ".join(mystrs) return f"{self.__class__.__name__}({mystrs_str})"
# =================================================================================================== # Switch type validators # ===================================================================================================
[docs]class Range(Validator): """ A switch-type validator that checks for the inclusion of a value in a certain range. Usage:: class MyApp(Application): age = SwitchAttr(["--age"], Range(18, 120)) :param start: The minimal value :param end: The maximal value """ __slots__ = ("start", "end") def __init__(self, start, end): self.start = start self.end = end def __repr__(self): return f"[{self.start:d}..{self.end:d}]" def __call__(self, obj): obj = int(obj) if obj < self.start or obj > self.end: raise ValueError( _("Not in range [{0:d}..{1:d}]").format(self.start, self.end) ) return obj
[docs] def choices(self, partial=""): # noqa: ARG002 # TODO: Add partial handling return set(range(self.start, self.end + 1))
[docs]class Set(Validator): """ A switch-type validator that checks that the value is contained in a defined set of values. Usage:: class MyApp(Application): mode = SwitchAttr(["--mode"], Set("TCP", "UDP", case_sensitive = False)) num = SwitchAttr(["--num"], Set("MIN", "MAX", int, csv = True)) :param values: The set of values (strings), or other callable validators, or types, or any other object that can be compared to a string. :param case_sensitive: A keyword argument that indicates whether to use case-sensitive comparison or not. The default is ``False`` :param csv: splits the input as a comma-separated-value before validating and returning a list. Accepts ``True``, ``False``, or a string for the separator :param all_markers: When a user inputs any value from this set, all values are iterated over. Something like {"*", "all"} would be a potential setting for this option. """ def __init__( self, *values: Union[str, Callable[[str], str]], case_sensitive: bool = False, csv: Union[bool, str] = False, all_markers: "[str]" = frozenset(), ) -> None: self.case_sensitive = case_sensitive if isinstance(csv, bool): self.csv = "," if csv else "" else: self.csv = csv self.values = values self.all_markers = all_markers def __repr__(self): items = ", ".join(v if isinstance(v, str) else v.__name__ for v in self.values) return f"{{{items}}}" def _call_iter( self, value: str, check_csv: bool = True ) -> Generator[str, None, None]: if self.csv and check_csv: for v in value.split(self.csv): yield from self._call_iter(v.strip(), check_csv=False) if not self.case_sensitive: value = value.lower() for opt in self.values: if isinstance(opt, str): if not self.case_sensitive: opt = opt.lower() # noqa: PLW2901 if opt == value or value in self.all_markers: yield opt # always return original value continue with contextlib.suppress(ValueError): yield opt(value) def __call__(self, value: str, check_csv: bool = True) -> Union[str, List[str]]: items = list(self._call_iter(value, check_csv)) if not items: msg = f"Invalid value: {value} (Expected one of {self.values})" raise ValueError(msg) if self.csv and check_csv or len(items) > 1: return items return items[0]
[docs] def choices(self, partial=""): choices = {opt if isinstance(opt, str) else f"({opt})" for opt in self.values} choices |= self.all_markers if partial: return {opt for opt in choices if opt.lower().startswith(partial)} return choices
CSV = Set(str, csv=True)
[docs]class Predicate: """A wrapper for a single-argument function with pretty printing""" def __init__(self, func): self.func = func def __str__(self): return self.func.__name__ def __call__(self, val): return self.func(val) # pylint: disable-next=no-self-use def choices(self, partial=""): # noqa: ARG002 return set()
@Predicate def ExistingDirectory(val): """A switch-type validator that ensures that the given argument is an existing directory""" p = local.path(val) if not p.is_dir(): raise ValueError(_("{0} is not a directory").format(val)) return p @Predicate def MakeDirectory(val): p = local.path(val) if p.is_file(): raise ValueError(f"{val} is a file, should be nonexistent, or a directory") if not p.exists(): p.mkdir() return p @Predicate def ExistingFile(val): """A switch-type validator that ensures that the given argument is an existing file""" p = local.path(val) if not p.is_file(): raise ValueError(_("{0} is not a file").format(val)) return p @Predicate def NonexistentPath(val): """A switch-type validator that ensures that the given argument is a nonexistent path""" p = local.path(val) if p.exists(): raise ValueError(_("{0} already exists").format(val)) return p