Hi Jason!
On Tue, Jan 12, 2010 at 12:19:36PM -0500, Jason Bandlow wrote:
> While working on this, I added a ``TestSuite(phi)`` test where ``phi``
> is a TriangularModuleMorphism, mimicking what was done for
> DiagonalModuleMorphism.
Good idea!
> Unfortunately, pickling fails. I don't really know where to start
> tracking this down... can you give me a pointer?
phi is constructed from f, which itself can't be pickled:
sage: X = CombinatorialFreeModule(QQ, [1, 2, 3]); X.rename("X")
sage: Y = CombinatorialFreeModule(QQ, [1, 2, 3]); y = Y.basis()
sage: f = lambda i: sum( y[j] for j in range(i,4) )
sage: loads(dumps(f))
------------------------------------------------------------
Traceback (most recent call last):
PicklingError: Can't pickle <type 'function'>: attribute lookup
__builtin__.function failed
That's because functions are pickled by name; but the name of f is
__main__.f. Pickles detects that there is no such function in the
__main__module, and rightfully deduces that f could not be unpickled
in a latter Sage session.
Luckily, one can cheat-around this, faking f being picklable, by
forcefully inserting it into __main__, as in:
sage: import __main__; __main__.f = f
Oh, and f should be defined with def, not lambda.
sage: X = CombinatorialFreeModule(QQ, [1, 2, 3]); X.rename("X")
sage: Y = CombinatorialFreeModule(QQ, [1, 2, 3]); y = Y.basis()
sage: def f(i): sum( y[j] for j in range(i,4) )
sage: import __main__; __main__.f = f
sage: loads(dumps(f))
<function f at 0xbfbc9cc>
sage: phi = X.module_morphism(f, triangular=True, codomain = Y)
sage: TestSuite(phi).run()
See the first example of TriangularModuleMorphism.
Altogether, whenever possible, I try to use standard sage functions
(like factorial) for such building blocks in tests. Here is a handy
trick, which involves a bit of magic in sum_of_terms (it's a morphism,
and therefore * is function composition):
sage: f = Y.sum_of_terms * range
sage: f(5)
B[0] + B[1] + B[2] + B[3] + B[4]
sage: loads(dumps(f))
A map to X
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
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