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Ruby

Posted by Roy Leung
Roy Leung
1,272 Points

How do I know which method would change the call object itself if there is no "!" required. It seems confused

like the function keep_if will change the call object itself but without symbol "!". It seems not consistency.

2 Answers

Dylan Shine
Dylan Shine
17,565 Points
Dylan Shine
Dylan Shine
17,565 Points

In the Ruby Code Docs (http://www.ruby-doc.org/core-2.1.3/Array.html#method-i-keep_if) there are methods that are destructive and non destructive. Since .keep_if is a destructive method, it will modify the array regardless of having a ! sign. To check if a method is destructive or now, look at whether the method you're using also has a ! version listed in the Ruby Core Docs.

Roy Leung
Roy Leung
1,272 Points

so that means, there is no ! sign version for destructive methods.

Dylan Shine
Dylan Shine
17,565 Points
Dylan Shine
Dylan Shine
17,565 Points

Correct, in order to not modify your array chances are you're going to need to duplicate it before you operate on it.