[ruby-core:123109] [Ruby Feature#21515] Add `&return` as sugar for `x=my_calculation; return x if x`

Issue #21515 has been updated by nhorton (Noah Horton).


nobu (Nobuyoshi Nakada) wrote in #note-3:
> Why not:
> ```ruby
> x = my_calculation(input_a, input_b) and return x
> ```

I have not seen it done this way. I will say that I started to say this did not work until I fully processed the `and` in this, so I am not sure on the legibility, but I think it is pretty good.

----------------------------------------
Feature #21515: Add `&return` as sugar for `x=my_calculation; return x if x`
https://bugs.ruby-lang.org/issues/21515#change-114426

* Author: nhorton (Noah Horton)
* Status: Open
----------------------------------------
Let me preface this by saying I have no marriage to the exact keyword name of `&return`.

# Problem
It is very common to have an early return in code where you get some initial value and return it if it is non-null. i.e.

```
return my_calculation(input_a, input_b) if my_calculation(input_a, input_b)
```

That form on its own is verbose and one where you need to look at it for a moment to confirm it is the same code on either side of the if.

If `my_calculation` is non-trivial at all, it normally gets turned into something with a variable:

```
my_calc = my_calculation(input_a, input_b)
return my_calc if my_calc
```

That is now two lines. The worse scenario, however, is if the user did not bother doing that and my_calculation turned out to be expensive (and they did not know it).

# Proposal
I propose a syntax of `&return my_calculation(input_a, input_b)` where it will evaluate the argument and return it as the result of the method if it is non-nil, otherwise it will continue on.

# Alternatives
## Do Nothing
There is no way to work around this with rolling your own methods. You can't make a `returnif` method or something yourself since you can't do a return in the caller's scope.

## Different Name

The best other name I saw were permutations of `returnif`. The biggest issue I see is the similarity of the following two statements:

```
return if foo
returnif foo
```

Those are obviously very, very different statements, but are somewhat similar. However, things like this are common, and the code is still quite distinct on those, so I think it is acceptable.

Ultimately, this feels so similar to the safe navigator that using `&` in this context feels appropriate.

Thank you all for your consideration.





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