Question

I have this code:

 settings[:base_name].gsub! /[\x00\/\\:\*\?\"<>\|]/, ''

When I run the script it throws an error:

gsub!': can't modify frozen String (RuntimeError)

I have changed the code to this:

 settings[:base_name] = settings[:base_name].gsub /[\x00\/\\:\*\?\"<>\|]/, ''

The code above works, but I don’t like at all, is there a way to properly use gsub! in this case?

Answer 1

No. Apparently, the API providing the string has frozen it, which means any method that modifies it will fail. Because gsub! modifies the string it is called on, a frozen object can not use gsub!. However, the variable that contains a frozen object can still be set to a non-frozen object, which is why your second code snippet works.

The API probably froze the object because it is a constant string that all of the instances share, and so one instance shouldn’t be able to ruin the string. But they do define a setter method, so you can set the value.