EDITLIST in CAS program

[StephenG1CMZ]

Actually, I wonder whether that should be a bug?
Using L1 := EDITLIST(L1)
Looks like a useful syntax for those times you want to edit a list and keep the original:
L2 := EDITLIST(L1)

If EDITLIST (L1) always changes L1, that last line would make
L2 = L1 = edited
Whereas
L2 = edited L1 =Original
Would be it's obvious meaning without looking up EDITLIST's spec.

So for readability of the source code, I would suggest EDITLIST should not automatically edit the list given as a parameter, though if no destination list is specified it should default to doing so).

A potential downside is that that might be less efficient, but it avoids
L2:=EDITLIST(L1) editing L1 when you might not expect it to.
If doing this is considered too wasteful given that on many occasions you will be editing back to the same list,
I would suggest EDITLIST should not be assignable - the corresponding code then becoming:
EDITLIST (L1); // no L2 makes it clear what is being edited
Or
L2:=L1; //keep original
EDITLIST (L2); // change copy
L2:=EDITLIST (L1) // could give syntax error to avoid confusion


I would also like to suggest EDITLIST should have an optional READONLY parameter (alternatively: a VIEWLIST command) for those times when you want to browse a list without changing it.
See for example how I use it in Version 0.3 of my Z EDITOR (select Searchall then View, and see how awkward the editing can look before my program implements search-and-replace). Having a readonly setting would be much neater.