Will Robertson

Nice use case `:)`. Many of the `_case` commands also are most commonly used with only the `F` branch and I'd see something similar here where `\file_if_exist_input:nnF` turns out to...

I think this does it: ``` \cs_new:Npn \dim_scale:nn #1#2 { #1 \__dim_eval:w #2 \__dim_eval_end: } ``` I agree would be a good addition.

Here is a better approach that uses "labels" instead and push/pop to move between them as needed. UI still needs work of course but the sketch of the idea is...

It looks like anything we do here should be imported directly from babel... already has \shorthandon \shorthandoff \useshorthands \defineshorthand etc. It doesn't have a push/pop approach but its language option...

You’re right about \protected. I didn’t think that through fully. I’m also not 100% push/pop is needed; I was thinking of the kind of use case where you might write...

Joseph: You're right there are plenty of situations where the line number isn't necessary or doesn't make sense. So I think you're right that it's sensible not to include it...

I'll consider adding some words to the documentation about "best practises for writing messages" before I close this immediately…

Given this discussion, then, I would propose two options: - compact, machine readable only - verbose, as currently but with file+lineno But in that case are "file+lineno” universally sensible? What...

I’m doubtful that we’ll ever see a situation in which the raw arguments could be usefully parsed — that’d involve a level of editor integration that we’ve never seen. So...

> !?@ no reason to keep them "other". In fact making @ letter would aid writing code that relies on 2e things. And !? being letters might open us up...