Is it possible to create a "handler" recipe?

[antonalekseev]

Given the following justfile

 set dotenv-load := false

mkenv:
    @echo "Create env"
    echo "FOO=1" > .env

build-ok: mkenv
    @echo "Build status OK"
    #!/usr/bin/env sh
    cat .env
    exit 0

build-failed: mkenv
    #!/usr/bin/env sh
    cat .env
    exit 1

cleanup:
    rm .env

I wonder if there is any way to run the cleanup recipe automatically on error to handle build-failed or when all the recipes are done implicitly? Something like trap or https://docs.python.org/3/library/atexit.html.

[casey]

There isn't currently a way to do this. I've been thinking about it, but not sure how to do it in a reasonable way. One idea, which I don't think is particularly good, is to add a new kind of dependency:

foo:

bar: || foo

Dependencies after only || run if the recipe fails, analogously to the current && dependency syntax, which runs after a recipe if it succeeds. I feel like this is probably too brittle, and won't work for enough use-cases to be worth it.

[patmaddox]

That is the exact syntax I thought of when I saw the && syntax.

Our use case is we have what we call a "doctor" script, which checks for certain conditions on the machine (e.g. env files in place, certain binaries, whatever). If a check fails, we print a proposed remedy out to the screen.

I'll experiment more with just as-is, but I did think || would be helpful for our use case.

[casey]

Thanks for commenting! I'd definitely be open to implementing ||, I have a weakness for weird features and weird syntax. Would you mind creating an issue describing your use-case, along with what behavior you'd like || to have? An example justfile would be great.

[jpeeler]

What if instead the subsequent dependency is prefixed with - to indicate to run always, especially in the case of error?

foo:
 
bar: && -foo

[casey]

I personally prefer ||, it just seems more natural to me.