nix flake show: add the description if it exists

[kjeremy]

Motivation

Displays the description of the package if it exists. This information is already present in the json output.

I have a flake with many packages and dev shells and this helps discoverability.

Context

10977

Priorities and Process

Add :+1: to pull requests you find important.

The Nix maintainer team uses a GitHub project board to schedule and track reviews.

[kjeremy]

This has been really helpful for my team. What do I need to do to get it merged?

[edolstra]

The problem with showing descriptions in nix flake show is that they can be pretty long, which can break the tree output rendering (especially if they contain newlines).

[kjeremy]

@edolstra I can think of a few approaches:

1. Strip newlines and maybe limit the length
2. Fix the tree views to work with multiline output

I can tackle either one if I get some direction.

[kjeremy]

I've pushed a change to stop at the first new line

[kjeremy]

I'm not quite sure how to test the output. The tests in tests/functional/flakes/show.sh all depend on the json output but this needs to check stdout.

[cole-h]

As a bystander, I think the following implementation might make the most sense:

• Strip all whitespace from the beginning of the description until you get to a non-whitespace character
• Read up to the next newline (if any)
• If the resulting string is longer than, say, 100 characters, trim it to that and add an ellipsis at the end

I'm not quite sure how to test the output. The tests in tests/functional/flakes/show.sh all depend on the json output but this needs to check stdout.

You could try using <the command> | grepQuiet "what you're looking for", I think.

[kjeremy]

I chose 80 and added tests.

[kjeremy]

@edolstra is this a reasonable solution to the tree rendering?

[kjeremy]

@Ericson2314 is there any thing I can do to move this along?

[kjeremy]

It looks like lix just merged this into their code base.

[kjeremy]

I think the macos test failure is spurious

[tomberek]

I tried this out and I still get overflow. Am I reading the logic wrong? Shouldn't the window size limitation be on the entire string rather than only the desc?

logger->cout("%s: %s '%s' - '%s'", headerPrefix, type, name, desc);
             ^-----------------^

[kjeremy]

I guess it could be. I was thinking it should just be on the description but maybe it should be on the whole string but we should only cut off the description if too long to match existing behavior

[tomberek]

Tested and works as expected. Thanks!