"""
This module contains the core `.Task` class & convenience decorators used to
generate new tasks.
"""
from copy import deepcopy
import inspect
import types
from .util import six
if six.PY3:
from itertools import zip_longest
else:
from itertools import izip_longest as zip_longest
from .context import Context
from .parser import Argument, translate_underscores
#: Sentinel object representing a truly blank value (vs ``None``).
NO_DEFAULT = object()
class Task(object):
"""
Core object representing an executable task & its argument specification.
For the most part, this object is a clearinghouse for all of the data that
may be supplied to the `@task <invoke.tasks.task>` decorator, such as
``name``, ``aliases``, ``positional`` etc, which appear as attributes.
In addition, instantiation copies some introspection/documentation friendly
metadata off of the supplied ``body`` object, such as ``__doc__``,
``__name__`` and ``__module__``, allowing it to "appear as" ``body`` for
most intents and purposes.
.. versionadded:: 1.0
"""
# TODO: store these kwarg defaults central, refer to those values both here
# and in @task.
# TODO: allow central per-session / per-taskmodule control over some of
# them, e.g. (auto_)positional, auto_shortflags.
# NOTE: we shadow __builtins__.help here on purpose - obfuscating to avoid
# it feels bad, given the builtin will never actually be in play anywhere
# except a debug shell whose frame is exactly inside this class.
def __init__(
self,
body,
name=None,
aliases=(),
positional=None,
optional=(),
default=False,
auto_shortflags=True,
help=None,
pre=None,
post=None,
autoprint=False,
iterable=None,
incrementable=None,
):
# Real callable
self.body = body
# Copy a bunch of special properties from the body for the benefit of
# Sphinx autodoc or other introspectors.
self.__doc__ = getattr(body, "__doc__", "")
self.__name__ = getattr(body, "__name__", "")
self.__module__ = getattr(body, "__module__", "")
# Default name, alternate names, and whether it should act as the
# default for its parent collection
self._name = name
self.aliases = aliases
self.is_default = default
# Arg/flag/parser hints
self.positional = self.fill_implicit_positionals(positional)
self.optional = optional
self.iterable = iterable or []
self.incrementable = incrementable or []
self.auto_shortflags = auto_shortflags
self.help = help or {}
# Call chain bidness
self.pre = pre or []
self.post = post or []
self.times_called = 0
# Whether to print return value post-execution
self.autoprint = autoprint
@property
def name(self):
return self._name or self.__name__
def __repr__(self):
aliases = ""
if self.aliases:
aliases = " ({})".format(", ".join(self.aliases))
return "<Task {!r}{}>".format(self.name, aliases)
def __eq__(self, other):
if self.name != other.name:
return False
# Functions do not define __eq__ but func_code objects apparently do.
# (If we're wrapping some other callable, they will be responsible for
# defining equality on their end.)
if self.body == other.body:
return True
else:
try:
return six.get_function_code(
self.body
) == six.get_function_code(other.body)
except AttributeError:
return False
def __hash__(self):
# Presumes name and body will never be changed. Hrm.
# Potentially cleaner to just not use Tasks as hash keys, but let's do
# this for now.
return hash(self.name) + hash(self.body)
def __call__(self, *args, **kwargs):
# Guard against calling tasks with no context.
if not isinstance(args[0], Context):
err = "Task expected a Context as its first arg, got {} instead!"
# TODO: raise a custom subclass _of_ TypeError instead
raise TypeError(err.format(type(args[0])))
result = self.body(*args, **kwargs)
self.times_called += 1
return result
@property
def called(self):
return self.times_called > 0
def argspec(self, body):
"""
Returns two-tuple:
* First item is list of arg names, in order defined.
* I.e. we *cannot* simply use a dict's ``keys()`` method here.
* Second item is dict mapping arg names to default values or
`.NO_DEFAULT` (an 'empty' value distinct from None, since None
is a valid value on its own).
.. versionadded:: 1.0
"""
# Handle callable-but-not-function objects
# TODO: __call__ exhibits the 'self' arg; do we manually nix 1st result
# in argspec, or is there a way to get the "really callable" spec?
func = body if isinstance(body, types.FunctionType) else body.__call__
spec = inspect.getargspec(func)
arg_names = spec.args[:]
matched_args = [reversed(x) for x in [spec.args, spec.defaults or []]]
spec_dict = dict(zip_longest(*matched_args, fillvalue=NO_DEFAULT))
# Pop context argument
try:
context_arg = arg_names.pop(0)
except IndexError:
# TODO: see TODO under __call__, this should be same type
raise TypeError("Tasks must have an initial Context argument!")
del spec_dict[context_arg]
return arg_names, spec_dict
def fill_implicit_positionals(self, positional):
args, spec_dict = self.argspec(self.body)
# If positionals is None, everything lacking a default
# value will be automatically considered positional.
if positional is None:
positional = []
for name in args: # Go in defined order, not dict "order"
default = spec_dict[name]
if default is NO_DEFAULT:
positional.append(name)
return positional
def arg_opts(self, name, default, taken_names):
opts = {}
# Whether it's positional or not
opts["positional"] = name in self.positional
# Whether it is a value-optional flag
opts["optional"] = name in self.optional
# Whether it should be of an iterable (list) kind
if name in self.iterable:
opts["kind"] = list
# If user gave a non-None default, hopefully they know better
# than us what they want here (and hopefully it offers the list
# protocol...) - otherwise supply useful default
opts["default"] = default if default is not None else []
# Whether it should increment its value or not
if name in self.incrementable:
opts["incrementable"] = True
# Argument name(s) (replace w/ dashed version if underscores present,
# and move the underscored version to be the attr_name instead.)
if "_" in name:
opts["attr_name"] = name
name = translate_underscores(name)
names = [name]
if self.auto_shortflags:
# Must know what short names are available
for char in name:
if not (char == name or char in taken_names):
names.append(char)
break
opts["names"] = names
# Handle default value & kind if possible
if default not in (None, NO_DEFAULT):
# TODO: allow setting 'kind' explicitly.
# NOTE: skip setting 'kind' if optional is True + type(default) is
# bool; that results in a nonsensical Argument which gives the
# parser grief in a few ways.
kind = type(default)
if not (opts["optional"] and kind is bool):
opts["kind"] = kind
opts["default"] = default
# Help
if name in self.help:
opts["help"] = self.help[name]
return opts
def get_arguments(self):
"""
Return a list of Argument objects representing this task's signature.
.. versionadded:: 1.0
"""
# Core argspec
arg_names, spec_dict = self.argspec(self.body)
# Obtain list of args + their default values (if any) in
# declaration/definition order (i.e. based on getargspec())
tuples = [(x, spec_dict[x]) for x in arg_names]
# Prime the list of all already-taken names (mostly for help in
# choosing auto shortflags)
taken_names = {x[0] for x in tuples}
# Build arg list (arg_opts will take care of setting up shortnames,
# etc)
args = []
for name, default in tuples:
new_arg = Argument(**self.arg_opts(name, default, taken_names))
args.append(new_arg)
# Update taken_names list with new argument's full name list
# (which may include new shortflags) so subsequent Argument
# creation knows what's taken.
taken_names.update(set(new_arg.names))
# Now we need to ensure positionals end up in the front of the list, in
# order given in self.positionals, so that when Context consumes them,
# this order is preserved.
for posarg in reversed(self.positional):
for i, arg in enumerate(args):
if arg.name == posarg:
args.insert(0, args.pop(i))
break
return args
[docs]def task(*args, **kwargs):
"""
Marks wrapped callable object as a valid Invoke task.
May be called without any parentheses if no extra options need to be
specified. Otherwise, the following keyword arguments are allowed in the
parenthese'd form:
* ``name``: Default name to use when binding to a `.Collection`. Useful for
avoiding Python namespace issues (i.e. when the desired CLI level name
can't or shouldn't be used as the Python level name.)
* ``aliases``: Specify one or more aliases for this task, allowing it to be
invoked as multiple different names. For example, a task named ``mytask``
with a simple ``@task`` wrapper may only be invoked as ``"mytask"``.
Changing the decorator to be ``@task(aliases=['myothertask'])`` allows
invocation as ``"mytask"`` *or* ``"myothertask"``.
* ``positional``: Iterable overriding the parser's automatic "args with no
default value are considered positional" behavior. If a list of arg
names, no args besides those named in this iterable will be considered
positional. (This means that an empty list will force all arguments to be
given as explicit flags.)
* ``optional``: Iterable of argument names, declaring those args to
have :ref:`optional values <optional-values>`. Such arguments may be
given as value-taking options (e.g. ``--my-arg=myvalue``, wherein the
task is given ``"myvalue"``) or as Boolean flags (``--my-arg``, resulting
in ``True``).
* ``iterable``: Iterable of argument names, declaring them to :ref:`build
iterable values <iterable-flag-values>`.
* ``incrementable``: Iterable of argument names, declaring them to
:ref:`increment their values <incrementable-flag-values>`.
* ``default``: Boolean option specifying whether this task should be its
collection's default task (i.e. called if the collection's own name is
given.)
* ``auto_shortflags``: Whether or not to automatically create short
flags from task options; defaults to True.
* ``help``: Dict mapping argument names to their help strings. Will be
displayed in ``--help`` output.
* ``pre``, ``post``: Lists of task objects to execute prior to, or after,
the wrapped task whenever it is executed.
* ``autoprint``: Boolean determining whether to automatically print this
task's return value to standard output when invoked directly via the CLI.
Defaults to False.
* ``klass``: Class to instantiate/return. Defaults to `.Task`.
If any non-keyword arguments are given, they are taken as the value of the
``pre`` kwarg for convenience's sake. (It is an error to give both
``*args`` and ``pre`` at the same time.)
.. versionadded:: 1.0
.. versionchanged:: 1.1
Added the ``klass`` keyword argument.
"""
klass = kwargs.pop("klass", Task)
# @task -- no options were (probably) given.
if len(args) == 1 and callable(args[0]) and not isinstance(args[0], Task):
return klass(args[0], **kwargs)
# @task(pre, tasks, here)
if args:
if "pre" in kwargs:
raise TypeError(
"May not give *args and 'pre' kwarg simultaneously!"
)
kwargs["pre"] = args
# @task(options)
# TODO: why the heck did we originally do this in this manner instead of
# simply delegating to Task?! Let's just remove all this sometime & see
# what, if anything, breaks.
name = kwargs.pop("name", None)
aliases = kwargs.pop("aliases", ())
positional = kwargs.pop("positional", None)
optional = tuple(kwargs.pop("optional", ()))
iterable = kwargs.pop("iterable", None)
incrementable = kwargs.pop("incrementable", None)
default = kwargs.pop("default", False)
auto_shortflags = kwargs.pop("auto_shortflags", True)
help = kwargs.pop("help", {})
pre = kwargs.pop("pre", [])
post = kwargs.pop("post", [])
autoprint = kwargs.pop("autoprint", False)
def inner(obj):
obj = klass(
obj,
name=name,
aliases=aliases,
positional=positional,
optional=optional,
iterable=iterable,
incrementable=incrementable,
default=default,
auto_shortflags=auto_shortflags,
help=help,
pre=pre,
post=post,
autoprint=autoprint,
# Pass in any remaining kwargs as-is.
**kwargs
)
return obj
return inner
class Call(object):
"""
Represents a call/execution of a `.Task` with given (kw)args.
Similar to `~functools.partial` with some added functionality (such as the
delegation to the inner task, and optional tracking of the name it's being
called by.)
.. versionadded:: 1.0
"""
def __init__(self, task, called_as=None, args=None, kwargs=None):
"""
Create a new `.Call` object.
:param task: The `.Task` object to be executed.
:param str called_as:
The name the task is being called as, e.g. if it was called by an
alias or other rebinding. Defaults to ``None``, aka, the task was
referred to by its default name.
:param tuple args:
Positional arguments to call with, if any. Default: ``None``.
:param dict kwargs:
Keyword arguments to call with, if any. Default: ``None``.
"""
self.task = task
self.called_as = called_as
self.args = args or tuple()
self.kwargs = kwargs or dict()
# TODO: just how useful is this? feels like maybe overkill magic
def __getattr__(self, name):
return getattr(self.task, name)
def __deepcopy__(self, memo):
return self.clone()
def __repr__(self):
aka = ""
if self.called_as is not None and self.called_as != self.task.name:
aka = " (called as: {!r})".format(self.called_as)
return "<{} {!r}{}, args: {!r}, kwargs: {!r}>".format(
self.__class__.__name__,
self.task.name,
aka,
self.args,
self.kwargs,
)
def __eq__(self, other):
# NOTE: Not comparing 'called_as'; a named call of a given Task with
# same args/kwargs should be considered same as an unnamed call of the
# same Task with the same args/kwargs (e.g. pre/post task specified w/o
# name). Ditto tasks with multiple aliases.
for attr in "task args kwargs".split():
if getattr(self, attr) != getattr(other, attr):
return False
return True
def make_context(self, config):
"""
Generate a `.Context` appropriate for this call, with given config.
.. versionadded:: 1.0
"""
return Context(config=config)
def clone_data(self):
"""
Return keyword args suitable for cloning this call into another.
.. versionadded:: 1.1
"""
return dict(
task=self.task,
called_as=self.called_as,
args=deepcopy(self.args),
kwargs=deepcopy(self.kwargs),
)
def clone(self, into=None, with_=None):
"""
Return a standalone copy of this Call.
Useful when parameterizing task executions.
:param into:
A subclass to generate instead of the current class. Optional.
:param dict with_:
A dict of additional keyword arguments to use when creating the new
clone; typically used when cloning ``into`` a subclass that has
extra args on top of the base class. Optional.
.. note::
This dict is used to ``.update()`` the original object's data
(the return value from its `clone_data`), so in the event of
a conflict, values in ``with_`` will win out.
.. versionadded:: 1.0
.. versionchanged:: 1.1
Added the ``with_`` kwarg.
"""
klass = into if into is not None else self.__class__
data = self.clone_data()
if with_ is not None:
data.update(with_)
return klass(**data)
def call(task, *args, **kwargs):
"""
Describes execution of a `.Task`, typically with pre-supplied arguments.
Useful for setting up :ref:`pre/post task invocations
<parameterizing-pre-post-tasks>`. It's actually just a convenient wrapper
around the `.Call` class, which may be used directly instead if desired.
For example, here's two build-like tasks that both refer to a ``setup``
pre-task, one with no baked-in argument values (and thus no need to use
`.call`), and one that toggles a boolean flag::
@task
def setup(c, clean=False):
if clean:
c.run("rm -rf target")
# ... setup things here ...
c.run("tar czvf target.tgz target")
@task(pre=[setup])
def build(c):
c.run("build, accounting for leftover files...")
@task(pre=[call(setup, clean=True)])
def clean_build(c):
c.run("build, assuming clean slate...")
Please see the constructor docs for `.Call` for details - this function's
``args`` and ``kwargs`` map directly to the same arguments as in that
method.
.. versionadded:: 1.0
"""
return Call(task=task, args=args, kwargs=kwargs)