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Ruby 2.5 added delete_prefix and delete_suffix methods

This blog is part of our Ruby 2.5 series.

Ruby 2.4

Let's say that we have a string Projects::CategoriesController and we want to remove Controller. We can use chomp method.

1irb> "Projects::CategoriesController".chomp("Controller")
2=> "Projects::Categories"

However if we want to remove Projects:: from the string then there is no corresponding method of chomp. We need to resort to sub.

1irb> "Projects::CategoriesController".sub(/Projects::/, '')
2=> "CategoriesController"

Naotoshi Seo did not like using regular expression for such a simple task. He proposed that Ruby should have a method for taking care of such tasks.

Some of the names proposed were remove_prefix, deprefix, lchomp, remove_prefix and head_chomp.

Matz suggested the name delete_prefix and this method was born.

Ruby 2.5.0-preview1

1irb> "Projects::CategoriesController".delete_prefix("Projects::")
2=> "CategoriesController"

Now in order to delete prefix we can use delete_prefix and to delete suffix we could use chomp. This did not feel right. So for symmetry delete_suffix was added.

1irb> "Projects::CategoriesController".delete_suffix("Controller")
2=> "Projects::Categories"

Read up on this discussion to learn more about how elixir, go, python, and PHP deal with similar requirements.

Amit Choudhary in Ruby 2.5
November 28, 2017

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