Subtle problems with `IsZmodnZVectorRep`, `IsZmodnZMatrixRep`

[ThomasBreuer]

Currently the basic functions that create these objects assign types which depend on the arguments and hence may be too specific.
For example, currently the following happens.

gap> R:= Integers mod 6;;
gap> z:= NewZeroVector( IsZmodnZVectorRep, R, 3 );;
gap> MakeImmutable( z );
<immutable vector mod 6: [ 0, 0, 0 ]>
gap> IsZero(z);
true
gap> HasIsZero(z);
true
gap> v:= Vector( [ 1, 2, 3 ], z );
<vector mod 6: [ 1, 2, 3 ]>
gap> IsZero( v );
true

The straightforward solution is to use the same approach as for IsPlistVectorRep and IsPlistMatrixRep.
I can provide a pull request for that.

[james-d-mitchell]

This looks like a bug to me. What is the approach taken for IsPlistVectorRep and IsPlistMatrixRep that you are referring to?

[ThomasBreuer]

This looks like a bug to me.

Yes, of course this is a bug, I should have added the relevant labels already in the beginning.

What is the approach taken for IsPlistVectorRep and IsPlistMatrixRep that you are referring to?

There are functions MakeIsPlistVectorRep and MakeIsPlistMatrixRep which are called by all methods that eventually have to create a new IsPlistVectorRep or IsPlistMatrixRep object. This way, there is just one place in the code where a type gets chosen and Objectify gets called.
(If it turns out that this approach is recommended for all new kinds of vector and matrix objects then it makes sense to document this.)

[fingolfin]

A patch would of course be welcome, great!