"""
Decorators
Python decorators for use in Sage.
AUTHORS:
- Tim Dumol (5 Dec 2009) -- initial version.
- Johan S. R. Nielsen (2010) -- collect decorators from various modules.
- Johan S. R. Nielsen (8 apr 2011) -- improve introspection on decorators.
- Simon King (2011-05-26) -- improve introspection of sage_wraps. Put this
file into the reference manual.
- Julian Rueth (2014-03-19): added ``decorator_keywords`` decorator
"""
#*****************************************************************************
# Copyright (C) 2009 Tim Dumol
# 2010,2011 Johan S. R. Nielsen
# 2011 Simon King <simon.king@uni-jena.de>
# 2014 Julian Rueth <julian.rueth@fsfe.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
# http://www.gnu.org/licenses/
#*****************************************************************************
from __future__ import print_function
from functools import (partial, update_wrapper, WRAPPER_ASSIGNMENTS,
WRAPPER_UPDATES)
from copy import copy
from sage.misc.sageinspect import (sage_getsource, sage_getsourcelines,
sage_getargspec)
from inspect import ArgSpec
def sage_wraps(wrapped, assigned=WRAPPER_ASSIGNMENTS, updated=WRAPPER_UPDATES):
r"""
Decorator factory which should be used in decorators for making sure that
meta-information on the decorated callables are retained through the
decorator, such that the introspection functions of
``sage.misc.sageinspect`` retrieves them correctly. This includes
documentation string, source, and argument specification. This is an
extension of the Python standard library decorator functools.wraps.
That the argument specification is retained from the decorated functions
implies, that if one uses ``sage_wraps`` in a decorator which intentionally
changes the argument specification, one should add this information to
the special attribute ``_sage_argspec_`` of the wrapping function (for an
example, see e.g. ``@options`` decorator in this module).
EXAMPLES:
Demonstrate that documentation string and source are retained from the
decorated function::
sage: def square(f):
....: @sage_wraps(f)
....: def new_f(x):
....: return f(x)*f(x)
....: return new_f
sage: @square
....: def g(x):
....: "My little function"
....: return x
sage: g(2)
4
sage: g(x)
x^2
sage: g.__doc__
'My little function'
sage: from sage.misc.sageinspect import sage_getsource, sage_getsourcelines, sage_getfile
sage: sage_getsource(g)
'@square...def g(x)...'
Demonstrate that the argument description are retained from the
decorated function through the special method (when left
unchanged) (see :trac:`9976`)::
sage: def diff_arg_dec(f):
....: @sage_wraps(f)
....: def new_f(y, some_def_arg=2):
....: return f(y+some_def_arg)
....: return new_f
sage: @diff_arg_dec
....: def g(x):
....: return x
sage: g(1)
3
sage: g(1, some_def_arg=4)
5
sage: from sage.misc.sageinspect import sage_getargspec
sage: sage_getargspec(g)
ArgSpec(args=['x'], varargs=None, keywords=None, defaults=None)
Demonstrate that it correctly gets the source lines and the source
file, which is essential for interactive code edition; note that we
do not test the line numbers, as they may easily change::
sage: P.<x,y> = QQ[]
sage: I = P*[x,y]
sage: sage_getfile(I.interreduced_basis)
'.../sage/interfaces/singular.py'
sage: sage_getsourcelines(I.interreduced_basis)
([' @singular_gb_standard_options\n',
' @libsingular_gb_standard_options\n',
' def interreduced_basis(self):\n',
...
' return self.basis.reduced()\n'], ...)
The ``f`` attribute of the decorated function refers to the
original function::
sage: foo = object()
sage: @sage_wraps(foo)
....: def func():
....: pass
sage: wrapped = sage_wraps(foo)(func)
sage: wrapped.f is foo
True
Demonstrate that sage_wraps works for non-function callables
(:trac:`9919`)::
sage: def square_for_met(f):
....: @sage_wraps(f)
....: def new_f(self, x):
....: return f(self,x)*f(self,x)
....: return new_f
sage: class T:
....: @square_for_met
....: def g(self, x):
....: "My little method"
....: return x
sage: t = T()
sage: t.g(2)
4
sage: t.g.__doc__
'My little method'
The bug described in :trac:`11734` is fixed::
sage: def square(f):
....: @sage_wraps(f)
....: def new_f(x):
....: return f(x)*f(x)
....: return new_f
sage: f = lambda x:x^2
sage: g = square(f)
sage: g(3) # this line used to fail for some people if these command were manually entered on the sage prompt
81
"""
#TRAC 9919: Workaround for bug in @update_wrapper when used with
#non-function callables.
assigned = set(assigned).intersection(set(dir(wrapped)))
#end workaround
def f(wrapper):
update_wrapper(wrapper, wrapped, assigned=assigned, updated=updated)
wrapper.f = wrapped
wrapper._sage_src_ = lambda: sage_getsource(wrapped)
wrapper._sage_src_lines_ = lambda: sage_getsourcelines(wrapped)
#Getting the signature right in documentation by Sphinx (Trac 9976)
#The attribute _sage_argspec_() is read by Sphinx if present and used
#as the argspec of the function instead of using reflection.
wrapper._sage_argspec_ = lambda: sage_getargspec(wrapped)
return wrapper
return f
# Infix operator decorator
class infix_operator(object):
"""
A decorator for functions which allows for a hack that makes
the function behave like an infix operator.
This decorator exists as a convenience for interactive use.
EXAMPLES:
An infix dot product operator::
sage: def dot(a,b): return a.dot_product(b)
sage: dot=infix_operator('multiply')(dot)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u *dot* v
22
An infix element-wise addition operator::
sage: def eadd(a,b):
....: return a.parent([i+j for i,j in zip(a,b)])
sage: eadd=infix_operator('add')(eadd)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u +eadd+ v
(6, 6, 6)
sage: 2*u +eadd+ v
(7, 8, 9)
A hack to simulate a postfix operator::
sage: def thendo(a,b): return b(a)
sage: thendo=infix_operator('or')(thendo)
sage: x |thendo| cos |thendo| (lambda x: x^2)
cos(x)^2
"""
def __init__(self, precedence):
"""
A decorator for functions which allows for a hack that makes
the function behave like an infix operator.
This decorator exists as a convenience for interactive use.
EXAMPLES::
sage: def dot(a,b): return a.dot_product(b)
sage: dot=infix_operator('multiply')(dot)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u *dot* v
22
sage: from sage.misc.decorators import infix_operator
sage: def eadd(a,b):
....: return a.parent([i+j for i,j in zip(a,b)])
sage: eadd=infix_operator('add')(eadd)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u +eadd+ v
(6, 6, 6)
sage: 2*u +eadd+ v
(7, 8, 9)
sage: from sage.misc.decorators import infix_operator
sage: def thendo(a,b): return b(a)
sage: thendo=infix_operator('or')(thendo)
sage: x |thendo| cos |thendo| (lambda x: x^2)
cos(x)^2
"""
self.precedence = precedence
operators = {'add': {'left': '__add__', 'right': '__radd__'},
'multiply': {'left': '__mul__', 'right': '__rmul__'},
'or': {'left': '__or__', 'right': '__ror__'},
}
def __call__(self, func):
"""
Returns a function which acts as an inline operator.
EXAMPLES::
sage: from sage.misc.decorators import infix_operator
sage: def dot(a,b): return a.dot_product(b)
sage: dot=infix_operator('multiply')(dot)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u *dot* v
22
sage: def eadd(a,b):
....: return a.parent([i+j for i,j in zip(a,b)])
sage: eadd=infix_operator('add')(eadd)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u +eadd+ v
(6, 6, 6)
sage: 2*u +eadd+ v
(7, 8, 9)
sage: def thendo(a,b): return b(a)
sage: thendo=infix_operator('or')(thendo)
sage: x |thendo| cos |thendo| (lambda x: x^2)
cos(x)^2
"""
def left_func(self, right):
"""
The function for the operation on the left (e.g., __add__).
EXAMPLES::
sage: def dot(a,b): return a.dot_product(b)
sage: dot=infix_operator('multiply')(dot)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u *dot* v
22
"""
if self.left is None:
if self.right is None:
new = copy(self)
new.right = right
return new
else:
raise SyntaxError("Infix operator already has its "
"right argument")
else:
return self.function(self.left, right)
def right_func(self, left):
"""
The function for the operation on the right (e.g., __radd__).
EXAMPLES::
sage: def dot(a,b): return a.dot_product(b)
sage: dot=infix_operator('multiply')(dot)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u *dot* v
22
"""
if self.right is None:
if self.left is None:
new = copy(self)
new.left = left
return new
else:
raise SyntaxError("Infix operator already has its "
"left argument")
else:
return self.function(left, self.right)
@sage_wraps(func)
class wrapper:
def __init__(self, left=None, right=None):
"""
Initialize the actual infix object, with possibly a
specified left and/or right operand.
EXAMPLES::
sage: def dot(a,b): return a.dot_product(b)
sage: dot=infix_operator('multiply')(dot)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: u *dot* v
22
"""
self.function = func
self.left = left
self.right = right
def __call__(self, *args, **kwds):
"""
Call the passed function.
EXAMPLES::
sage: def dot(a,b): return a.dot_product(b)
sage: dot=infix_operator('multiply')(dot)
sage: u=vector([1,2,3])
sage: v=vector([5,4,3])
sage: dot(u,v)
22
"""
return self.function(*args, **kwds)
setattr(wrapper, self.operators[self.precedence]['left'], left_func)
setattr(wrapper, self.operators[self.precedence]['right'], right_func)
wrapper._sage_src_ = lambda: sage_getsource(func)
return wrapper()
def decorator_defaults(func):
"""
This function allows a decorator to have default arguments.
Normally, a decorator can be called with or without arguments.
However, the two cases call for different types of return values.
If a decorator is called with no parentheses, it should be run
directly on the function. However, if a decorator is called with
parentheses (i.e., arguments), then it should return a function
that is then in turn called with the defined function as an
argument.
This decorator allows us to have these default arguments without
worrying about the return type.
EXAMPLES::
sage: from sage.misc.decorators import decorator_defaults
sage: @decorator_defaults
....: def my_decorator(f,*args,**kwds):
....: print(kwds)
....: print(args)
....: print(f.__name__)
sage: @my_decorator
....: def my_fun(a,b):
....: return a,b
{}
()
my_fun
sage: @my_decorator(3,4,c=1,d=2)
....: def my_fun(a,b):
....: return a,b
{'c': 1, 'd': 2}
(3, 4)
my_fun
"""
@sage_wraps(func)
def my_wrap(*args, **kwds):
if len(kwds) == 0 and len(args) == 1:
# call without parentheses
return func(*args)
else:
return lambda f: func(f, *args, **kwds)
return my_wrap
class suboptions(object):
def __init__(self, name, **options):
"""
A decorator for functions which collects all keywords
starting with ``name+'_'`` and collects them into a dictionary
which will be passed on to the wrapped function as a
dictionary called ``name_options``.
The keyword arguments passed into the constructor are taken
to be default for the ``name_options`` dictionary.
EXAMPLES::
sage: from sage.misc.decorators import suboptions
sage: s = suboptions('arrow', size=2)
sage: s.name
'arrow_'
sage: s.options
{'size': 2}
"""
self.name = name + "_"
self.options = options
def __call__(self, func):
"""
Returns a wrapper around func
EXAMPLES::
sage: from sage.misc.decorators import suboptions
sage: def f(*args, **kwds): print(list(sorted(kwds.items())))
sage: f = suboptions('arrow', size=2)(f)
sage: f(size=2)
[('arrow_options', {'size': 2}), ('size', 2)]
sage: f(arrow_size=3)
[('arrow_options', {'size': 3})]
sage: f(arrow_options={'size':4})
[('arrow_options', {'size': 4})]
sage: f(arrow_options={'size':4}, arrow_size=5)
[('arrow_options', {'size': 5})]
Demonstrate that the introspected argument specification of the
wrapped function is updated (see :trac:`9976`).
sage: from sage.misc.sageinspect import sage_getargspec
sage: sage_getargspec(f)
ArgSpec(args=['arrow_size'], varargs='args', keywords='kwds', defaults=(2,))
"""
@sage_wraps(func)
def wrapper(*args, **kwds):
suboptions = copy(self.options)
suboptions.update(kwds.pop(self.name+"options", {}))
#Collect all the relevant keywords in kwds
#and put them in suboptions
for key, value in kwds.items():
if key.startswith(self.name):
suboptions[key[len(self.name):]] = value
del kwds[key]
kwds[self.name + "options"] = suboptions
return func(*args, **kwds)
#Add the options specified by @options to the signature of the wrapped
#function in the Sphinx-generated documentation (Trac 9976), using the
#special attribute _sage_argspec_ (see e.g. sage.misc.sageinspect)
def argspec():
argspec = sage_getargspec(func)
def listForNone(l):
return l if not l is None else []
newArgs = [self.name + opt for opt in self.options.keys()]
args = (argspec.args if not argspec.args is None else []) + newArgs
defaults = (argspec.defaults if not argspec.defaults is None else ()) \
+ tuple(self.options.values())
#Note: argspec.defaults is not always a tuple for some reason
return ArgSpec(args, argspec.varargs, argspec.keywords, defaults)
wrapper._sage_argspec_ = argspec
return wrapper
class options(object):
def __init__(self, **options):
"""
A decorator for functions which allows for default options to be
set and reset by the end user. Additionally, if one needs to, one
can get at the original keyword arguments passed into the
decorator.
TESTS::
sage: from sage.misc.decorators import options
sage: o = options(rgbcolor=(0,0,1))
sage: o.options
{'rgbcolor': (0, 0, 1)}
sage: o = options(rgbcolor=(0,0,1), __original_opts=True)
sage: o.original_opts
True
sage: loads(dumps(o)).options
{'rgbcolor': (0, 0, 1)}
Demonstrate that the introspected argument specification of the wrapped
function is updated (see :trac:`9976`)::
sage: from sage.misc.decorators import options
sage: o = options(rgbcolor=(0,0,1))
sage: def f(*args, **kwds):
....: print("{} {}".format(args, list(sorted(kwds.items()))))
sage: f1 = o(f)
sage: from sage.misc.sageinspect import sage_getargspec
sage: sage_getargspec(f1)
ArgSpec(args=['rgbcolor'], varargs='args', keywords='kwds', defaults=((0, 0, 1),))
"""
self.options = options
self.original_opts = options.pop('__original_opts', False)
def __call__(self, func):
"""
EXAMPLES::
sage: from sage.misc.decorators import options
sage: o = options(rgbcolor=(0,0,1))
sage: def f(*args, **kwds):
....: print("{} {}".format(args, list(sorted(kwds.items()))))
sage: f1 = o(f)
sage: f1()
() [('rgbcolor', (0, 0, 1))]
sage: f1(rgbcolor=1)
() [('rgbcolor', 1)]
sage: o = options(rgbcolor=(0,0,1), __original_opts=True)
sage: f2 = o(f)
sage: f2(alpha=1)
() [('__original_opts', {'alpha': 1}), ('alpha', 1), ('rgbcolor', (0, 0, 1))]
"""
@sage_wraps(func)
def wrapper(*args, **kwds):
options = copy(wrapper.options)
if self.original_opts:
options['__original_opts'] = kwds
options.update(kwds)
return func(*args, **options)
#Add the options specified by @options to the signature of the wrapped
#function in the Sphinx-generated documentation (Trac 9976), using the
#special attribute _sage_argspec_ (see e.g. sage.misc.sageinspect)
def argspec():
argspec = sage_getargspec(func)
args = (argspec.args if not argspec.args is None else []) + self.options.keys()
defaults = tuple(argspec.defaults if not argspec.defaults is None else ()) + tuple(self.options.values())
#Note: argspec.defaults is not always a tuple for some reason
return ArgSpec(args, argspec.varargs, argspec.keywords, defaults)
wrapper._sage_argspec_ = argspec
def defaults():
"""
Return the default options.
EXAMPLES::
sage: from sage.misc.decorators import options
sage: o = options(rgbcolor=(0,0,1))
sage: def f(*args, **kwds):
....: print("{} {}".format(args, list(sorted(kwds.items()))))
sage: f = o(f)
sage: f.options['rgbcolor']=(1,1,1)
sage: f.defaults()
{'rgbcolor': (0, 0, 1)}
"""
return copy(self.options)
def reset():
"""
Reset the options to the defaults.
EXAMPLES::
sage: from sage.misc.decorators import options
sage: o = options(rgbcolor=(0,0,1))
sage: def f(*args, **kwds):
....: print("{} {}".format(args, list(sorted(kwds.items()))))
sage: f = o(f)
sage: f.options
{'rgbcolor': (0, 0, 1)}
sage: f.options['rgbcolor']=(1,1,1)
sage: f.options
{'rgbcolor': (1, 1, 1)}
sage: f()
() [('rgbcolor', (1, 1, 1))]
sage: f.reset()
sage: f.options
{'rgbcolor': (0, 0, 1)}
sage: f()
() [('rgbcolor', (0, 0, 1))]
"""
wrapper.options = copy(self.options)
wrapper.options = copy(self.options)
wrapper.reset = reset
wrapper.reset.__doc__ = """
Reset the options to the defaults.
Defaults:
%s
""" % self.options
wrapper.defaults = defaults
wrapper.defaults.__doc__ = """
Return the default options.
Defaults:
%s
""" % self.options
return wrapper
class rename_keyword(object):
def __init__(self, deprecated=None, deprecation=None, **renames):
"""
A decorator which renames keyword arguments and optionally
deprecates the new keyword.
INPUT:
- ``deprecation`` -- integer. The trac ticket number where the
deprecation was introduced.
- the rest of the arguments is a list of keyword arguments in the
form ``renamed_option='existing_option'``. This will have the
effect of renaming ``renamed_option`` so that the function only
sees ``existing_option``. If both ``renamed_option`` and
``existing_option`` are passed to the function, ``existing_option``
will override the ``renamed_option`` value.
EXAMPLES::
sage: from sage.misc.decorators import rename_keyword
sage: r = rename_keyword(color='rgbcolor')
sage: r.renames
{'color': 'rgbcolor'}
sage: loads(dumps(r)).renames
{'color': 'rgbcolor'}
To deprecate an old keyword::
sage: r = rename_keyword(deprecation=13109, color='rgbcolor')
"""
assert deprecated is None, 'Use @rename_keyword(deprecation=<trac_number>, ...)'
self.renames = renames
self.deprecation = deprecation
def __call__(self, func):
"""
Rename keywords.
EXAMPLES::
sage: from sage.misc.decorators import rename_keyword
sage: r = rename_keyword(color='rgbcolor')
sage: def f(*args, **kwds):
....: print("{} {}".format(args, kwds))
sage: f = r(f)
sage: f()
() {}
sage: f(alpha=1)
() {'alpha': 1}
sage: f(rgbcolor=1)
() {'rgbcolor': 1}
sage: f(color=1)
() {'rgbcolor': 1}
We can also deprecate the renamed keyword::
sage: r = rename_keyword(deprecation=13109, deprecated_option='new_option')
sage: def f(*args, **kwds):
....: print("{} {}".format(args, kwds))
sage: f = r(f)
sage: f()
() {}
sage: f(alpha=1)
() {'alpha': 1}
sage: f(new_option=1)
() {'new_option': 1}
sage: f(deprecated_option=1)
doctest:...: DeprecationWarning: use the option 'new_option' instead of 'deprecated_option'
See http://trac.sagemath.org/13109 for details.
() {'new_option': 1}
"""
@sage_wraps(func)
def wrapper(*args, **kwds):
for old_name, new_name in self.renames.items():
if old_name in kwds and new_name not in kwds:
if self.deprecation is not None:
from sage.misc.superseded import deprecation
deprecation(self.deprecation, "use the option "
"%r instead of %r" % (new_name, old_name))
kwds[new_name] = kwds[old_name]
del kwds[old_name]
return func(*args, **kwds)
return wrapper
class specialize:
r"""
A decorator generator that returns a decorator that in turn
returns a specialized function for function ``f``. In other words,
it returns a function that acts like ``f`` with arguments
``*args`` and ``**kwargs`` supplied.
INPUT:
- ``*args``, ``**kwargs`` -- arguments to specialize the function for.
OUTPUT:
- a decorator that accepts a function ``f`` and specializes it
with ``*args`` and ``**kwargs``
EXAMPLES::
sage: f = specialize(5)(lambda x, y: x+y)
sage: f(10)
15
sage: f(5)
10
sage: @specialize("Bon Voyage")
....: def greet(greeting, name):
....: print("{0}, {1}!".format(greeting, name))
sage: greet("Monsieur Jean Valjean")
Bon Voyage, Monsieur Jean Valjean!
sage: greet(name = 'Javert')
Bon Voyage, Javert!
"""
def __init__(self, *args, **kwargs):
self.args = args
self.kwargs = kwargs
def __call__(self, f):
return sage_wraps(f)(partial(f, *self.args, **self.kwargs))
def decorator_keywords(func):
r"""
A decorator for decorators with optional keyword arguments.
EXAMPLES::
sage: from sage.misc.decorators import decorator_keywords
sage: @decorator_keywords
....: def preprocess(f=None, processor=None):
....: def wrapper(*args, **kwargs):
....: if processor is not None:
....: args, kwargs = processor(*args, **kwargs)
....: return f(*args, **kwargs)
....: return wrapper
This decorator can be called with and without arguments::
sage: @preprocess
....: def foo(x): return x
sage: foo(None)
sage: foo(1)
1
sage: def normalize(x): return ((0,),{}) if x is None else ((x,),{})
sage: @preprocess(processor=normalize)
....: def foo(x): return x
sage: foo(None)
0
sage: foo(1)
1
"""
@sage_wraps(func)
def wrapped(f=None, **kwargs):
if f is None:
return sage_wraps(func)(lambda f:func(f, **kwargs))
else:
return func(f, **kwargs)
return wrapped