ViewString for enumerator uses method for list

[markuspf]

Using GAP in the terminal, viewing an enumerator behaves reasonably:

gap> e := Enumerator(SymmetricGroup(5));
<enumerator of perm group>
gap> ViewObj(e);
<enumerator of perm group>

But the method selected for ViewString is the one for a list, and hence the enumerator is expanded. This is not what we want:

ViewString returns a string which would be displayed by ViewObj (6.3-5) for an object.

gap> e := Enumerator(SymmetricGroup(5));
<enumerator of perm group>
gap> ViewString(e);
"[ (),\<\> (1,\<\>5),\<\> (1,\<\>2,\<\>5),\<\> (1,\<\>3,\<\>5),\<\> (1,\<\>4,\<\>5),\
\<\> (2,\<\>5),... (continues for another 50 lines or so)

See gap-packages/JupyterKernel#72

[fingolfin]

I just became aware of this issue, and to be frank, I don't understand what it is about. What is wrong? Please amend the issue description to explain that.

[ChrisJefferson]

This shows the problem:

gap> e := Enumerator(SymmetricGroup(5));;
gap> ViewString(e);
"[ (),\<\> (1,\<\>5),\<\> (1,\<\>2,\<\>5),\<\> (1,\<\>3,\<\>5),\<\> (1,\<\>4,\<\>5),\
\<\> (2,\<\>5),... (continues for another 50 lines or so)

[wilfwilson]

I updated the issue description and removed the status: awaiting response label, since I feel that the issue is now sufficiently clear.

[ThomasBreuer]

I think this issue has the following aspects.

• Design and documentation of enumerators in IsEnumeratorByFunctions should be changed
  such that a ViewString component is supported.
• Analogously, support PrintString.
• Analogously, do the same for IsIteratorByFunctions.
• Objects in IsEnumeratorByFunctions and IsIteratorByFunctions need
  ViewString and PrintStringmethods analogous to their ViewObj and PrintObj methods.
• Concerning the JupyterKernel context, the problem is more general.
  A change as proposed in prefer ViewObj to ViewString (temporarily) gap-packages/JupyterKernel#104
  would provide a temporary solution to problems of this kind
  until sufficiently many ViewString methods are available.

If this sounds reasonable then I can create a pull request for the changes sketched above.