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"Useless syntax sugar": Numbered block parameters in Ruby
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Damn, I wish rust had that
It wouldn't be as relevant, since passing a function or method instead of a closure is much easier in Rust - you can just name it, while Ruby requires you to use the
method
method.So instead of
.map(|res| res.unwrap())
you can do.map(Result::unwrap)
and it'll Just Work™.In the case of your example we'd do
.map(&:unwrap)
in Ruby (if unwrap was a method we'd actually want to call)Notably, these are not the cases
_1
and_2
etc are for. They are there for the cases that are not structurally "call this method on the single argument to the block" e.g..map{ _1 + _2 }
or.map { x.foo(_1) }
(
_1
is reasonable, because iterating over an enumerable sequence makes it obvious what it is;_1
and_2
combined is often reasonable, because e.g. if we iterate over a key, value enumerable, such as what you get from enumerating aHash
, it's obvious what you get; if you find yourself using_3
or above, you're turning to the dark side and should rethink your entire life)