Avoid regex if possible checking for \AssignTemplateKeys

[josephwright]

READ ME FIRST: Please understand that in most cases we will not be able to merge a pull request because there are a lot of internal activities needed when updating the LaTeX2e sources. If you have a code suggestion please discuss it with the team first.

Internal housekeeping

Status of pull request

• Feedback wanted
• Under development
• Ready to merge

Checklist of required changes before merge will be approved

• Test file(s) added
• Version and date string updated in changed source files
• Relevant \changes entries in source included
• Relevant changes.txt updated
• Rollback provided (if necessary)?
• ltnewsX.tex (and/or latexchanges.tex) updated

[josephwright]

@Skillmon Take a look?

[Skillmon]

Less likely false-positives (marginally, I admit):

Suggested change

	\str_if_in:nnTF {#5} { AssignTemplateKeys }
	\str_if_in:nnTF {#5} { \AssignTemplateKeys }

[josephwright]

I'd thought about this - I missed out the backslash just in case we are in a context where it's not the escape char. I agree it's very much an edge case.

[Skillmon]

Not sure whether this is desirable, but one could reduce code duplication here using the following code

                \str_if_in:nnT {#5} { \AssignTemplateKeys }
                  {
                    \regex_match:nnT { \c { AssignTemplateKeys } } {#5}
                      {
                        \@@_declare_template_code:nnnn {#1} {#2} {#3} {#5}
                        \prg_break:
                      }
                  }
                \@@_declare_template_code:nnnn
                  {#1} {#2} {#3} { \AssignTemplateKeys #5 }
                \prg_break_point:

[FrankMittelbach]

Would \AssignTemplateKeys inside a group in the code of a template make any sense? If not, then this should perhaps be documented and you could go \tl_if_in...but I guess in reality any of the tests are fine.

[josephwright]

We have one case in a group: enotez - it though uses \group_begin:/\group_end:. We could document this and make a formally breaking change - do we want to do that?

[FrankMittelbach]

I was just wondering if it would make sense at all. If in a group the assignments would get reverted at the end of the group wouldn't they? so what happens then in enotez?

[josephwright]

The reason we kept \AssignTemplateKeys in the first place was that you might want to either save/restore variables or (as in enotez) use a group to keep changes to each use case

[FrankMittelbach]

ok then there are use cases for using \AssignTemplateKeys in a group, so we can't check using \tl_if_in..., so let's forget it.

[josephwright]

Well expl3 groups really should be \group_begin: ... \group_end: not {..}, but it's hard to be 100% sure

[FrankMittelbach]

arguably yes, but then as you say that is a bit hard to enforce and it is not critically slower to use a str test here (given that this happens only during declarations). So I think we are good.