"""
This module provides SunPy specific decorators.
"""
import types
import inspect
import textwrap
import warnings
import functools
from inspect import Parameter, signature
from functools import wraps
import astropy.units as u
from astropy.nddata import NDData
from sunpy.util.exceptions import SunpyDeprecationWarning, SunpyPendingDeprecationWarning, warn_deprecated
__all__ = ['deprecated']
def get_removal_version(since):
# Work out which version this will be removed in
since_major, since_minor = since.split('.')[:2]
since_lts = since_minor == '0'
if since_lts:
major = int(since_major)
minor = int(since_minor) + 1
else:
major = int(since_major) + 1
minor = 1
return major, minor
[docs]
def deprecated(since, message='', name='', alternative='', pending=False,
obj_type=None):
"""
Used to mark a function or class as deprecated.
Parameters
----------
since : str
The release at which this API became deprecated. This is
required.
message : str, optional
Override the default deprecation message. The format
specifier ``func`` may be used for the name of the function,
and ``alternative`` may be used in the deprecation message
to insert the name of an alternative to the deprecated
function. ``obj_type`` may be used to insert a friendly name
for the type of object being deprecated.
name : str, optional
The name of the deprecated function or class; if not provided
the name is automatically determined from the passed in
function or class, though this is useful in the case of
renamed functions, where the new function is just assigned to
the name of the deprecated function. For example::
def new_function():
...
oldFunction = new_function
alternative : str, optional
An alternative function or class name that the user may use in
place of the deprecated object. The deprecation warning will
tell the user about this alternative if provided.
pending : bool, optional
If True, uses a SunpyPendingDeprecationWarning instead of a
``warning_type``.
obj_type : str, optional
The type of this object, if the automatically determined one
needs to be overridden.
"""
major, minor = get_removal_version(since)
removal_version = f"{major}.{minor}"
# TODO: replace this with the astropy deprecated decorator
return _deprecated(since, message=message, name=name, alternative=alternative, pending=pending,
removal_version=removal_version, obj_type=obj_type,
warning_type=SunpyDeprecationWarning,
pending_warning_type=SunpyPendingDeprecationWarning)
def _deprecated(since, message='', name='', alternative='', pending=False, removal_version=None,
obj_type=None, warning_type=SunpyDeprecationWarning,
pending_warning_type=SunpyPendingDeprecationWarning):
# TODO: remove this once the removal_version kwarg has been added to the upstream
# astropy deprecated decorator
method_types = (classmethod, staticmethod, types.MethodType)
def deprecate_doc(old_doc, message):
"""
Returns a given docstring with a deprecation message prepended
to it.
"""
if not old_doc:
old_doc = ''
old_doc = textwrap.dedent(old_doc).strip('\n')
new_doc = (('\n.. deprecated:: {since}'
'\n {message}\n\n'.format(
**{'since': since, 'message': message.strip()})) + old_doc)
if not old_doc:
# This is to prevent a spurious 'unexpected unindent' warning from
# docutils when the original docstring was blank.
new_doc += r'\ '
return new_doc
def get_function(func):
"""
Given a function or classmethod (or other function wrapper type), get
the function object.
"""
if isinstance(func, method_types):
func = func.__func__
return func
def deprecate_function(func, message, warning_type=warning_type):
"""
Returns a wrapped function that displays ``warning_type``
when it is called.
"""
if isinstance(func, method_types):
func_wrapper = type(func)
else:
def func_wrapper(f):
return f
func = get_function(func)
def deprecated_func(*args, **kwargs):
if pending:
category = pending_warning_type
else:
category = warning_type
warnings.warn(message, category, stacklevel=2)
return func(*args, **kwargs)
# If this is an extension function, we can't call
# functools.wraps on it, but we normally don't care.
# This crazy way to get the type of a wrapper descriptor is
# straight out of the Python 3.3 inspect module docs.
if not isinstance(func, type(str.__dict__['__add__'])):
deprecated_func = functools.wraps(func)(deprecated_func)
deprecated_func.__doc__ = deprecate_doc(
deprecated_func.__doc__, message)
return func_wrapper(deprecated_func)
def deprecate_class(cls, message, warning_type=warning_type):
"""
Update the docstring and wrap the ``__init__`` in-place (or ``__new__``
if the class or any of the bases overrides ``__new__``) so it will give
a deprecation warning when an instance is created.
This won't work for extension classes because these can't be modified
in-place and the alternatives don't work in the general case:
- Using a new class that looks and behaves like the original doesn't
work because the __new__ method of extension types usually makes sure
that it's the same class or a subclass.
- Subclassing the class and return the subclass can lead to problems
with pickle and will look weird in the Sphinx docs.
"""
cls.__doc__ = deprecate_doc(cls.__doc__, message)
if cls.__new__ is object.__new__:
cls.__init__ = deprecate_function(get_function(cls.__init__),
message, warning_type)
else:
cls.__new__ = deprecate_function(get_function(cls.__new__),
message, warning_type)
return cls
def deprecate(obj, message=message, name=name, alternative=alternative,
pending=pending, warning_type=warning_type):
if obj_type is None:
if isinstance(obj, type):
obj_type_name = 'class'
elif inspect.isfunction(obj):
obj_type_name = 'function'
elif inspect.ismethod(obj) or isinstance(obj, method_types):
obj_type_name = 'method'
else:
obj_type_name = 'object'
else:
obj_type_name = obj_type
if not name:
name = get_function(obj).__name__
altmessage = ''
if not message or isinstance(message, type(deprecate)):
if pending:
message = ('The {func} {obj_type} will be deprecated in '
'version {deprecated_version}.')
else:
message = ('The {func} {obj_type} is deprecated and may '
'be removed in {future_version}.')
if alternative:
altmessage = f'\n Use {alternative} instead.'
if removal_version is None:
future_version = 'a future version'
else:
future_version = f'version {removal_version}'
message = ((message.format(**{
'func': name,
'name': name,
'deprecated_version': since,
'future_version': future_version,
'alternative': alternative,
'obj_type': obj_type_name})) +
altmessage)
if isinstance(obj, type):
return deprecate_class(obj, message, warning_type)
else:
return deprecate_function(obj, message, warning_type)
if isinstance(message, type(deprecate)):
return deprecate(message)
return deprecate
class add_common_docstring:
"""
A function decorator that will append and/or prepend an addendum to the
docstring of the target function.
Parameters
----------
append : `str`, optional
A string to append to the end of the functions docstring.
prepend : `str`, optional
A string to prepend to the start of the functions docstring.
**kwargs : `dict`, optional
A dictionary to format append and prepend strings.
"""
def __init__(self, append=None, prepend=None, **kwargs):
if kwargs:
append = append
prepend = prepend
self.append = append
self.prepend = prepend
self.kwargs = kwargs
def __call__(self, func):
func.__doc__ = func.__doc__ if func.__doc__ else ''
self.append = self.append if self.append else ''
self.prepend = self.prepend if self.prepend else ''
if self.append and isinstance(func.__doc__, str):
func.__doc__ += self.append
if self.prepend and isinstance(func.__doc__, str):
func.__doc__ = self.prepend + func.__doc__
if self.kwargs:
func.__doc__ = func.__doc__.format(**self.kwargs)
return func
def deprecate_positional_args_since(since, keyword_only=False):
"""
Decorator for methods that issues warnings for positional arguments
Using the keyword-only argument syntax in pep 3102, arguments after the
* will issue a warning when passed as a positional argument.
Note that when you apply this, you also have to put at * in the signature
to create new keyword only parameters!
Parameters
----------
since : str
Parameter denoting last supported version.
"""
def deprecate_positional_args(f):
"""
Parameters
----------
f : function
Function to check arguments on.
References
----------
Taken from from `scikit-learn <https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/utils/validation.py#L1271>`__.
Licensed under the BSD, see "licenses/SCIKIT-LEARN.rst".
"""
nonlocal keyword_only
sig = signature(f)
kwonly_args = []
all_args = []
keyword_only = keyword_only or tuple()
for name, param in sig.parameters.items():
if param.kind == Parameter.POSITIONAL_OR_KEYWORD:
all_args.append(name)
elif param.kind == Parameter.KEYWORD_ONLY:
kwonly_args.append(name)
@wraps(f)
def inner_f(*args, **kwargs):
extra_args = len(args) - len(all_args)
if extra_args > 0:
for name, arg in zip(kwonly_args[:extra_args], args[-extra_args:]):
if name in keyword_only:
raise TypeError(f"{name} must be specified as a keyword argument.")
# ignore first 'self' argument for instance methods
args_msg = [f'{name}={arg}'
for name, arg in zip(kwonly_args[:extra_args],
args[-extra_args:])]
last_supported_version = ".".join(map(str, get_removal_version(since)))
warn_deprecated(f"Pass {', '.join(args_msg)} as keyword args. "
f"From version {last_supported_version} "
"passing these as positional arguments will result in an error.")
kwargs.update({k: arg for k, arg in zip(sig.parameters, args)})
return f(**kwargs)
return inner_f
return deprecate_positional_args
_NOT_FOUND = object()
def cached_property_based_on(attr_name):
"""
A decorator to cache the value of a property based on the output of a
different class attribute.
This decorator caches the values of ``getattr(instance, method)`` and
``prop(instance)``. When the decorated property is accessed,
``getattr(instance, method)`` is called. If this returns the same as its
cached value, the cached value of ``prop`` is returned. Otherwise both
``meth`` and ``prop`` are recomputed, cached, and the new value of ``prop``
is returned.
Parameters
----------
attr_name
The name of the attribute, on which changes are checked for. The actual
attribute is accessed using ``getattr(attr_name, instance)``.
Notes
-----
The cached value of ``meth(instance)`` is stored under the key ``meth.__name__``.
"""
def outer(prop):
"""
prop: the property method being decorated
"""
@wraps(outer)
def inner(instance):
"""
Parameters
----------
instance
Any class instance that has the property ``prop``,
and attribute ``attr``.
"""
cache = instance.__dict__
prop_key = prop.__name__
# Check if our caching method has changed output
new_attr_val = getattr(instance, attr_name)
old_attr_val = cache.get(attr_name, _NOT_FOUND)
if (old_attr_val is _NOT_FOUND or
new_attr_val != old_attr_val or
prop_key not in cache):
# Store the new attribute value
cache[attr_name] = new_attr_val
# Recompute the property
new_val = prop(instance)
cache[prop_key] = new_val
return cache[prop_key]
return inner
return outer
def check_arithmetic_compatibility(func):
"""
A decorator to check if an arithmetic operation can
be performed between a map instance and some other operation.
"""
@wraps(func)
def inner(instance, value):
# This is explicit because it is expected that users will try to do this. This raises
# a different error because it is expected that this type of operation will be supported
# in future releases.
if isinstance(value, NDData):
return NotImplemented
try:
# We want to support operations between numbers and array-like objects. This includes
# floats, ints, lists (of the aforementioned), arrays, quantities. This test acts as
# a proxy for these possible inputs. If it can be cast to a unitful quantity, we can
# do arithmetic with it. Broadcasting or unit mismatches are handled later in the
# actual operations by numpy and astropy respectively.
_ = u.Quantity(value, copy=False)
except TypeError:
return NotImplemented
return func(instance, value)
return inner
