QueryOne!: Support /./ to immediately get term + -default when 0 results

[osnr]

Saves a lot of code repetition -- we've been using lindex, dict getdef, and list length comparisons very repetitively when querying imperatively.

See Discord: https://discord.com/channels/956758212152025098/956765077883744266/1510000054507802785

Need to test that this didn't break anything.

[smj-edison]

Do you allow flags to be passed in after query parameters? I suppose this is more of an edge case, but -- might be needed in the future.

[osnr]

Generally, I think we allow flags anywhere? + it reads better this way, I think, without the letter right up next to paper

[osnr]

Yeah, I like the idea of eventually supporting --

[smj-edison]

Would you want a flag like -takefirst instead of try/on here?

[smj-edison]

Or I suppose this is just in case nothing is returned, never mind.

[s-ol]

Neat. /./ is a new bit of "syntax", right? I'm wondering if using uplevel to match When's binding logic could make sense:

AssignOne! the paper formats are /formats/
# equivalent to
set formats [QueryOne! the paper formats are /./]

# enables multiple capture (still enforcing single overall match)
AssignOne! the /medium/ formats are /formats/

You could also specify defaults inline, although that requires introducing specialized syntax once again:

AssignOne! the /medium=paper/ formats are /formats={letter a4}/

[osnr]

Neat. /./ is a new bit of "syntax", right? I'm wondering if using uplevel to match When's binding logic could make sense:

AssignOne! the paper formats are /formats/
# equivalent to
set formats [QueryOne! the paper formats are /./]

# enables multiple capture (still enforcing single overall match)
AssignOne! the /medium/ formats are /formats/

You could also specify defaults inline, although that requires introducing specialized syntax once again:

AssignOne! the /medium=paper/ formats are /formats={letter a4}/

I like this idea. Reads more cleanly than set x .... We were talking about Expect or Observe for a reactive variant of this. This could be Expect!, maybe. @smj-edison what do you think?

[smj-edison]

Agreed, that's much cleaner. Just a note, but if someone does /name=$default/ it'll substitute into a single string without any escaping, so I guess parse accordingly. Also, the example with /formats={letter a4}/ will parse as two tokens, since the parser is in normal string mode since it didn't open with a brace. It would have to be {/formats=letter a4/}.

[osnr]

[osnr]

Maybe we introduce Expect! with no defaults for now, since that covers a lot of the cases here, then think about further syntax later?

Expect! the fps is /fps or 3/ could work as well if we're going to parse multiple tokens anyway

[smj-edison]

So essentially scan ahead until you see a token ending in /? That makes a lot of sense. String injection is also harder to pull off because of Tcl's escaping rules.

[smj-edison]

Oops, I forgot to respond to Expect!. I think it's a good idea to introduce it as Expect! now, and we can extend it later.

[smj-edison]

Oh further thought, and at risk of breaking Tcl's string transparency, when you evaluate a function like Expect!, you could look at the script being evaluated, and you could make sure that the trailing / comes from a string token and not from a cobbled together source.