String concatenation
The + method and interpolation create a new String. On the other hand, the << method directly modifies the instance of the variable a. In Ruby, Strings are not immutable ⚠️.
With more than 3 concatenations (and even 2!), always prefer interpolation to the + method:
+can only be used to concatenate Strings, while interpolation implicitly calls theto_smethod.- A String is created for each call to
+, while interpolation creates only one.
The << method is preferable to += if the original instance can be modified. It can also take an integer as argument, which will be converted to a String via the codepoint.
If you need to concatenate several arguments or even prefix, Ruby has thought of everything, almost! The implementation of concat is the same as <<, also allowing an integer. This is not the case with prepend, which only accepts Strings and doesn’t have the equivalent >> operator.
