@something: a short-circuiting something

[omus]

In the AWS.jl package I was noticing a pattern where if an argument was undefined a series of fallbacks would be tried. The code was similar to:

if region === nothing
    region === nothing && (region = get(ENV, "AWS_REGION", nothing)
    region === nothing && (region = get_profile_region())
    region === nothing && (region = get_ec2_instance_region())
    region === nothing && (region = DEFAULT_REGION)
end

Since the code above makes use of nothing using the something function is a natural fit:

something(
    region,
    get(ENV, "AWS_REGION", nothing),
    get_profile_region(),
    get_ec2_instance_region(),
    DEFAULT_REGION,
)

This is much easier to read but unfortunately evaluates all arguments even if they aren't used. The @something macro is equivalent to something but skips evaluating all argument after the first non-nothing value.

[omus]

I'll add a NEWS entry tomorrow

[jw3126]

Nice! Would it make sence to also have @coalesce?

[omus]

Nice! Would it make sence to also have @coalesce?

That can definitely be added. I just didn't have a use case for it

[omus]

• Added NEWS entry
• Added short-circuiting @coalesce
• Fixed a minor documentation error which made it appear that something and coalesce required at least one argument.

[omus]

CI failure is from the LibCURL stdlib and is unrelated

[ararslan]

Ah, I forgot to mention that these should have a compat annotation in the docstrings.

[omus]

Ah, I forgot to mention that these should have a compat annotation in the docstrings.

I'll take care of that now