#13998: hash of a pickled Sequence is broken
------------------------+---------------------------------------------------
Reporter: slabbe | Owner: slabbe
Type: defect | Status: new
Priority: major | Milestone: sage-5.7
Component: pickling | Keywords:
Work issues: | Report Upstream: N/A
Reviewers: | Authors:
Merged in: | Dependencies:
Stopgaps: |
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The following works::
{{{
sage: M = ModularSymbols(1,12,sign=1)
sage: M
Modular Symbols space of dimension 2 for Gamma_0(1) of weight 12 with
sign 1 over Rational Field
sage: S =
M.cuspidal_submodule().decomposition()[0].free_module().basis()
sage: type(S)
<class 'sage.structure.sequence.Sequence_generic'>
sage: S
[
(1, 0)
]
sage: hash(S)
979268961
}}}
But if you do the same from a certain pickled object, it is broken (tested
on sage-4.7 and sage-5.6.rc0)::
{{{
sage: M =
load('http://sage.math.washington.edu/home/slabbe/LMFDB/mstest.sobj')
Attempting to load remote file:
http://sage.math.washington.edu/home/slabbe/LMFDB/mstest.sobj
Loading: [.]
sage: M
Modular Symbols space of dimension 2 for Gamma_0(1) of weight 12 with
sign 1 over Rational Field
sage: S =
M.cuspidal_submodule().decomposition()[0].free_module().basis()
sage: type(S)
<class 'sage.structure.sequence.Sequence_generic'>
sage: S
[
(1, 0)
]
sage: hash(S)
Traceback (most recent call last)
...
AttributeError: 'Sequence_generic' object has no attribute
'_Sequence_generic__hash'
}}}
This particular problem was reported by LMFDB developper who understands
that Sage do not guarrenty that pickled object are supported by later
version of Sage.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13998>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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