[ruby-core:105074] [Ruby master Bug#18135] Introduce Enumerable#detect_only
From:
"meisel (Michael Eisel)" <noreply@...>
Date:
2021-08-26 19:18:26 UTC
List:
ruby-core #105074
Issue #18135 has been reported by meisel (Michael Eisel).
----------------------------------------
Bug #18135: Introduce Enumerable#detect_only
https://bugs.ruby-lang.org/issues/18135
* Author: meisel (Michael Eisel)
* Status: Open
* Priority: Normal
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
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It can be important to get the only element for which a block returns true, and to assert that this is the only element as such. For example, this can be a very helpful sanity check when one is working with data that's outside of their control and is not perfectly understood. They may have a guess as to how to get a specific element matching some criteria, but if they used Enumerable#detect might be hiding the fact that they have written an incorrect block and that there's in fact more than one element that matches it. It could also be a parameter on Typically, I'd do it like this:
```
matches = array.select { |elem| some_method(elem) }
raise if matches.size != 0
match = matches.first
```
Here, it would be shortened to:
```
match = array.detect_only { |elem| some_method(elem) }
```
It could also be a parameter on Enumerable#detect instead of a separate method.
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