h3h.net

I really like Ruby’s idiomatic use of ? and ! token characters at the end of method names to indicate the method’s purpose: a predicate or a mutator (or otherwise destructive method), respectively. The benefits can be seen with examples.

If the task is replacing a substring inside of a larger string, JavaScript would have it done like this:

str = str.replace(/foo/g, 'bar');

The issue here, especially when you have a long LHS, is that the str = str... bit becomes redundant. In Ruby you could mirror this code as such:

str = str.gsub(/foo/, 'bar');

But then it gets better. Ruby has another method, gsub! that uses the mutator idiom to accomplish the same task in place. The code becomes:

str.gsub!(/foo/, 'bar');

This just ends up being much cleaner and more direct, in my opinion. I would love to see this idiom spread to other languages, especially ones in which I have a personal interest (JavaScript/ES4, Python). There are several more examples of these idioms throughout Ruby code that I won’t get into here, but hopefully you see the benefit from this small snippet.

See also: String.gsub!, FileTest.exist?, Array.flatten!