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
- sage.misc.decorators.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.misc.decorators.decorator_keywords(func)#
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
- class sage.misc.decorators.infix_operator(precedence)#
Bases:
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: @infix_operator('multiply') ....: def dot(a, b): ....: '''Dot product.''' ....: return a.dot_product(b) sage: u = vector([1, 2, 3]) sage: v = vector([5, 4, 3]) sage: u *dot* v 22
An infix element-wise addition operator:
sage: @infix_operator('add') ....: def eadd(a, b): ....: return a.parent([i + j for i, j in zip(a, b)]) 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: @infix_operator('or') ....: def thendo(a, b): ....: return b(a) sage: x |thendo| cos |thendo| (lambda x: x^2) cos(x)^2
- operators = {'add': {'left': '__add__', 'right': '__radd__'}, 'multiply': {'left': '__mul__', 'right': '__rmul__'}, 'or': {'left': '__or__', 'right': '__ror__'}}#
- class sage.misc.decorators.options(**options)#
Bases:
object
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.
- class sage.misc.decorators.rename_keyword(deprecated=None, deprecation=None, **renames)#
Bases:
object
A decorator which renames keyword arguments and optionally deprecates the new keyword.
INPUT:
deprecation
– integer. The github issue 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 renamingrenamed_option
so that the function only seesexisting_option
. If bothrenamed_option
andexisting_option
are passed to the function,existing_option
will override therenamed_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')
- sage.misc.decorators.sage_wraps(wrapped, assigned=('__module__', '__name__', '__qualname__', '__doc__', '__annotations__'), updated=('__dict__',))#
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 github issue #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) FullArgSpec(args=['x'], varargs=None, varkw=None, defaults=None, kwonlyargs=[], kwonlydefaults=None, annotations={})
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) # known bug '.../sage/rings/polynomial/multi_polynomial_ideal.py' sage: sage_getsourcelines(I.interreduced_basis) ([' @handle_AA_and_QQbar\n', ' @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 (github issue #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 github issue #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
- class sage.misc.decorators.specialize(*args, **kwargs)#
Bases:
object
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 likef
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!
- class sage.misc.decorators.suboptions(name, **options)#
Bases:
object
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 calledname_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}