Unique copies of rings in CoCoA-5
If a user creates the same ring twice, should he get the exact same ring?
Use QQ[x]; f := x; Use QQ[x]; g := x; f+g; --> should this work?
Currently, CoCoA-5 creates two distinct but "identical" rings, so
MixedRingserror. This is quite close to a nasty surprise.
#1 Updated by John Abbott about 4 years ago
Conceptually this issue seems practically identical to #482.
Yet, I think they are slightly independent: if CoCoALib makes unique copies of rings then CoCoA-5 pretty much has no choice, but CoCoA-5 could make unique copies even if CoCoALib does not: e.g. CoCoA-5 maintains a global registry of rings, but CoCoALib does not.
To facilitate the porting of CoCoA-5 code into CoCoALib it is probably best that two adopt the same policy.