Opened 10 years ago
Closed 6 years ago
#12603 closed defect (fixed)
copying cached_methods does not work properly
Reported by:  saraedum  Owned by:  jason 

Priority:  minor  Milestone:  sage6.4 
Component:  misc  Keywords:  cached_method, cache, days71 
Cc:  SimonKing  Merged in:  
Authors:  Julian Rüth  Reviewers:  David Roe, Aly Deines 
Report Upstream:  N/A  Work issues:  
Branch:  90147ca (Commits, GitHub, GitLab)  Commit:  90147cae0db60208896a36e2ac3d87c8c2027c63 
Dependencies:  Stopgaps: 
Description
A few funny things can happen when copying cached methods:
sage: class A: ... @cached_method ... def f(self): ... return 1 ... sage: class B: ... g=A.f ... def f(self): ... return 2 ... ... sage: b=B() sage: b.f() 2 sage: b.g() 1 sage: b.f() 1
The problem is that a call to b.g leads to a new MethodCaller? in b.f; something similar happens here:
sage: class C: ... g=A.f ... sage: c=C() sage: c.g is c.g False sage: c.g is c.f True
Change History (17)
comment:1 Changed 10 years ago by
 Type changed from PLEASE CHANGE to defect
comment:2 Changed 8 years ago by
 Milestone changed from sage5.11 to sage5.12
comment:3 Changed 8 years ago by
 Milestone changed from sage6.1 to sage6.2
comment:4 Changed 8 years ago by
 Milestone changed from sage6.2 to sage6.3
comment:5 Changed 7 years ago by
 Milestone changed from sage6.3 to sage6.4
comment:6 Changed 6 years ago by
 Branch set to u/saraedum/copying_cached_methods_does_not_work_properly
comment:7 Changed 6 years ago by
 Commit set to d85263804f48b54e9869914c9a96f9c42253eb9e
 Status changed from new to needs_review
New commits:
d852638  Cached methods can not be copied.

comment:8 Changed 6 years ago by
 Status changed from needs_review to needs_work
Need to use ....: doctest continuations rather than ...
comment:9 Changed 6 years ago by
 Commit changed from d85263804f48b54e9869914c9a96f9c42253eb9e to 90147cae0db60208896a36e2ac3d87c8c2027c63
comment:10 Changed 6 years ago by
 Status changed from needs_work to needs_review
comment:11 Changed 6 years ago by
Looks good. Positive review once the tests all pass.
comment:12 Changed 6 years ago by
 Keywords days71 added
 Status changed from needs_review to positive_review
All tests pass. :)
comment:14 Changed 6 years ago by
 Reviewers set to David Roe
 Status changed from needs_work to positive_review
Aly, you can add yourself if you like. ;)
comment:15 Changed 6 years ago by
 Reviewers changed from David Roe to David Roe, Aly Deines
comment:16 Changed 6 years ago by
Merge conflict, possibly with #15692
comment:17 Changed 6 years ago by
 Branch changed from u/saraedum/copying_cached_methods_does_not_work_properly to 90147cae0db60208896a36e2ac3d87c8c2027c63
 Resolution set to fixed
 Status changed from positive_review to closed
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Is that a new bug (i.e., introduced by my code from #11115)?
Anyway, it is not clear to me how the problem could be solved. Namely, a cached method knows the name under which it was defined, but if one assigns it to a different name afterwards, I see no way for the cached method to find out that new name.