Default to short printing for REPL #168

Keno · 2021-07-10T01:33:56Z

The printing choices in this package are somewhat non-standard
with respect to how Base defines printing, though that is
probably Base's fault for not documenting how these are
supposed to be used properly. In particular, this package
uses the :compact switch to decide between a parseable,
verbose printing and a compact, human-readable printing.

However, these are orthogonal concepts, and the :compact
switch isn't really supposed to switch the parsability.
Parsability vs non-parsibility is the distinction between
show(io::IO, x) (parseable) and show(io::IO, MIME"text/plain"(), x)
(non-parseable, pretty for humans). The latter is also
what is used for display in REPL contexts whereas the former
is used for repr.

I would like to suggest that the REPL printing should also
default to the human-readable version. For example, I
wanted to use intervals of units in a package, but the
default output looks very scary for first time Julia users:

julia> using Intervals, Unitful

julia> 1dB..2dB
Interval{Gain{Unitful.LogInfo{:Decibel, 10, 10}, :?, Int64}, Closed, Closed}(1 dB, 2 dB)

Admittedly that is mostly because of the scary Unitful type,
but still. We have better printing, why not use it. After this PR,
the compact printing is used at the REPL:

julia> 1dB..2dB
[1 dB .. 2 dB]

The printing choices in this package are somewhat non-standard with respect to how Base defines printing, though that is probably Base's fault for not documenting how these are supposed to be used properly. In particular, this package uses the :compact switch to decide between a parseable, verbose printing and a compact, human-readable printing. However, these are orthogonal concepts, and the :compact switch isn't really supposed to switch the parsability. Parsability vs non-parsibility is the distinction between `show(io::IO, x)` (parseable) and `show(io::IO, MIME"text/plain"(), x)` (non-parseable, pretty for humans). The latter is also what is used for display in REPL contexts whereas the former is used for repr. I would like to suggest that the REPL printing should also default to the human-readable version. For example, I wanted to use intervals of units in a package, but the default output looks very scary for first time Julia users: ``` julia> using Intervals, Unitful julia> 1dB..2dB Interval{Gain{Unitful.LogInfo{:Decibel, 10, 10}, :?, Int64}, Closed, Closed}(1 dB, 2 dB) ``` Admittedly that is mostly because of the scary Unitful type, but still. We have better printing, why not use it. ``` julia> 1dB..2dB [1 dB .. 2 dB] ```

This is sort of an expansion of invenia#168. There I tried to keep the PR fairly minimal to only fix the specific case that was bothering me. Here I try a more extensive set of changes to show some options of what might be possible. Some subset of these may be interesting, so I'm opening this for discussion with the maximum set of possible changes and we can discuss from there. First things first, here's some demo printing: ``` julia> a = Interval{Closed, Open}(DateTime(2013, 2, 13), DateTime(2013, 2, 13, 1)) ［2013-02-13T00:00:00, 2013-02-13T01:00:00） julia> show(a) Interval{Closed,Open}(DateTime("2013-02-13T00:00:00"), DateTime("2013-02-13T00:00:00")) julia> show(IOContext(stdout, :compact=>true), a) i`［DateTime("2013-02-13T00:00:00"),DateTime("2013-02-13T01:00:00")）` julia> i`［DateTime("2013-02-13T00:00:00"),DateTime("2013-02-13T01:00:00")）` ［2013-02-13T00:00:00, 2013-02-13T01:00:00） julia> const dB = Unitful.dB dB julia> 1 dB .. 2 dB 1 dB .. 2 dB julia> i`(1dB, 2dB]` （1 dB, 2 dB］ ``` The most obvious change, is probably the introduction of the i_cmd macro that parses back the short interval syntax and is used for compact, parseable print. Here's the feature highlights of this scheme: - Compact printing is changed to use the unicode double-wide brackets, to distinguish it from ascii brackets, which already have a different meaning - `show(::IO, x::Interval)` is always parseable, both in compact mode and in non-compact mode. Note that the compact interval printing changed from using `..` to `,`. This is to clarify the parsing rules inside the macro. In particular, other than the first and last character, the macro uses tuple parsing rules, so you can do things like: ``` julia> i`(now(), now()+Hour(1)]` （2021-07-10T02:51:37.780, 2021-07-10T03:51:37.780］ ``` - The i-macro parses both ASCII and double-wide brackets as interval bounds - The parseable and non-parseable printing now generally only differs in the printing or non-printing of the i-macro. This is quite useful to get something parseable back from an interval that was printed in non-parseable context. - Closed intervals have special printing using the `..` operator to make the output match the input syntax. Of course they can also be constructed using the i-macro (but will still be printed as `..`). - Even for non-compact, parseable prinitng, the long type parameter is dropped, in favor of only showing the Open/Closed setting, since the type should be redunant with the parsing of the bounds being printed. As I said, several of these are independent, so we might only want a subset of these, but I thought, I'd present it as one big thing. This doesn't have any doc(test) changes yet, since I figure things will change, and I didn't want to bother doing that twice :).

Keno requested a review from omus as a code owner July 10, 2021 01:33

Keno mentioned this pull request Jul 10, 2021

RFC: More printing overhaul #169

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Default to short printing for REPL #168

Default to short printing for REPL #168

Keno commented Jul 10, 2021

Default to short printing for REPL #168

Are you sure you want to change the base?

Default to short printing for REPL #168

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Keno commented Jul 10, 2021