add paging to help> prompt ( #36460)

[Pramodh-G]

Fixes #36460 .
Thanks

[fredrikekre]

I think this should be configurable somehow.

[Pramodh-G]

@fredrikekre . would an environment variable similar to things like JULIA_WARN_COLOR et. al help here?

But these values are set by repl_color() here which makes me think that it would be weird to have an environment variable for this.

[fredrikekre]

Perhaps .julia/config/REPL.toml, or something more advanced using Preferences.jl interface. Such a file can then also be used for e.g. colors and colorschemes.

[Pramodh-G]

should I open a separate issue for this? It seems to be a bigger issue since it applies to all the REPL config including colors.

[StefanKarpinski]

Issue opened with some questions: #41435.

[ViralBShah]

Shouldn't we merge this while we make it more configurable?

[Pramodh-G]

bump

[Pramodh-G]

bumping again :)

[oscardssmith]

Adding a triage label to decide if we want this. I'm in favor.

[JeffBezanson]

In general this is a good thing to have. First, I'm not sure this is the right place to implement it. It looks like this should move closer to the presentation layer (higher up the stack in the REPL)? Second, I have some issues with how the pager works. It would be nice if you didn't need to press an extra key when the output fits on one page.

[JeffBezanson]

I also see some artifacts, for example I can get into this state easily:

(15 / 45)  33%
(15 / 45)  33%
(15 / 45)  33%
(22 / 45)  49%
(23 / 45)  51%
(24 / 45)  53%
(25 / 45)  56%
(26 / 45)  58%
(27 / 45)  60%
(28 / 45)  62%
(29 / 45)  64%
(30 / 45)  67%
(31 / 45)  69%
(32 / 45)  71%
(33 / 45)  73%
^     1
      2
   
     sort(A; dims::Integer, alg::Algorithm=DEFAULT_UNSTABLE, lt=isless, by=identity, rev::Bool=false, order::Ordering=Forward)
   
     Sort a multidimensional array A along the given dimension. See sort! for a
     description of possible keyword arguments.
   
     To sort slices of an array, refer to sortslices.
   
     Examples
     ≡≡≡≡≡≡≡≡≡≡
   
 >   julia> A = [4 3; 1 2]
v    2×2 Matrix{Int64}:

[jakobnissen]

I think that bug is an instance of #39198 (i.e. it is caused by the line containing the method signature, because it is longer than the TerminalMenu line width)

[fingolfin]

Anyone who wants paging in the help prompt: I recommend the wonderful https://github.com/ronisbr/TerminalPager.jl package. While it does not enable paging on the ? help prompt, it adds a "pager prompt" and from there one can get paging help (just type | to enter the pager prompt, then ? to enter the pager help prompt). Or one can press Alt-h anywhere in the regular REPL prompt, and it shows the help for the word under the cursor. So nice.