Function Mangling#
This module provides utilities for extracting information about python functions.
AUTHORS:
Tom Boothby (2009): Original version in Python
Simon King (2011): Use Cython. Speedup of
fix_to_pos
, cleaning documentation.
- class sage.misc.function_mangling.ArgumentFixer#
Bases:
object
This class provides functionality to normalize the arguments passed into a function. While the various ways of calling a function are perfectly equivalent from the perspective of the callee, they don’t always look the same for an object watching the caller. For example,
sage: def f(x = 10): ....: return min(1,x)
the following calls are equivalent,
sage: f() 1 sage: f(10) 1 sage: f(x=10) 1
but from the perspective of a wrapper, they are different:
sage: def wrap(g): ....: def _g(*args,**kwargs): ....: print("{} {}".format(args, kwargs)) ....: return g(*args, **kwargs) ....: return _g sage: h = wrap(f) sage: t = h() () {} sage: t = h(10) (10,) {} sage: t = h(x=10) () {'x': 10}
For the purpose of cached functions, it is important not to distinguish between these uses.
INPUT:
f – a function
classmethod – boolean (default False) – True if the function is a classmethod and therefore the first argument is expected to be the class instance. In that case, we ignore the first argument.
EXAMPLES:
sage: from sage.misc.function_mangling import ArgumentFixer sage: def wrap2(g): ....: af = ArgumentFixer(g) ....: def _g(*args, **kwargs): ....: print(af.fix_to_pos()) ....: return g(*args,**kwargs) ....: return _g sage: h2 = wrap2(f) sage: t = h2() ((10,), ()) sage: t = h2(10) ((10,), ()) sage: t = h2(x=10) ((10,), ())
sage: class one: ....: def __init__(self, x = 1): ....: self.x = x sage: af = ArgumentFixer(one.__init__, classmethod=True) sage: af.fix_to_pos(1,2,3,a=31,b=2,n=3) ((1, 2, 3), (('a', 31), ('b', 2), ('n', 3)))
- f#
- fix_to_named(*args, **kwargs)#
Normalize the arguments with a preference for named arguments.
INPUT:
any positional and named arguments.
OUTPUT:
We return a tuple
\((e_1, e_2, ..., e_k), ((n_1, v_1), ... , (n_m, v_m))\)
where \(n_1, ... , n_m\) are the names of the arguments and \(v_1, ..., v_m\) are the values passed in; and \(e_1, ..., e_k\) are the unnamed arguments. We minimize \(k\).
The defaults are extracted from the function and filled into the list
K
of named arguments. The names \(n_1, ..., n_t\) are in order of the function definition, where \(t\) is the number of named arguments. The remaining names, \(n_{t+1}, ..., n_m\) are given in alphabetical order. This is useful to extract the names of arguments, but does not maintain equivalence ofA,K = self.fix_to_pos(...) self.f(*A,**dict(K))`
and
self.f(...)
in all cases.
EXAMPLES:
sage: from sage.misc.function_mangling import ArgumentFixer sage: def sum3(a,b,c=3,*args,**kwargs): ....: return a+b+c sage: AF = ArgumentFixer(sum3) sage: AF.fix_to_named(1,2,3,4,5,6,f=14,e=16) ((4, 5, 6), (('a', 1), ('b', 2), ('c', 3), ('e', 16), ('f', 14))) sage: AF.fix_to_named(1,2,f=14) ((), (('a', 1), ('b', 2), ('c', 3), ('f', 14)))
- fix_to_pos(*args, **kwds)#
Normalize the arguments with a preference for positional arguments.
INPUT:
Any positional or named arguments
OUTPUT:
We return a tuple
\((e_1, e_2, ..., e_k), ((n_1, v_1), ... , (n_m, v_m))\)
where \(n_1, ... , n_m\) are the names of the arguments and \(v_1, ..., v_m\) are the values passed in; and \(e_1, ..., e_k\) are the unnamed arguments. We minimize \(m\).
The commands
A,K = self.fix_to_pos(...) self.f(*A,**dict(K))
are equivalent to
self.f(...)
though defaults are extracted from the function and appended to the tuple
A
of positional arguments. The names \(n_1, ..., n_m\) are given in alphabetical order.EXAMPLES:
sage: from sage.misc.function_mangling import ArgumentFixer sage: def do_something(a, b, c=3, *args, **kwargs): ....: print("{} {} {} {} {}".format(a, b, c, args, ....: sorted(kwargs.items()))) sage: AF = ArgumentFixer(do_something) sage: A, K = AF.fix_to_pos(1, 2, 3, 4, 5, 6, f=14, e=16) sage: print("{} {}".format(A, K)) (1, 2, 3, 4, 5, 6) (('e', 16), ('f', 14)) sage: do_something(*A, **dict(K)) 1 2 3 (4, 5, 6) [('e', 16), ('f', 14)] sage: do_something(1, 2, 3, 4, 5, 6, f=14, e=16) 1 2 3 (4, 5, 6) [('e', 16), ('f', 14)]