Strings

• Vectors containing 8-bit characters.

• String literals yield canonical strings, which are immutable. No two canonical strings have the same sequence of characters. Can use identity (==) to test equality.

• Sending copyMutable to a canonical string gives you a mutable string. Responds to at:Put: , etc.

• Useful methods in traits string.

Strings

There are two kinds of strings in Self, mutable strings and immutable strings, also known as canonical strings.

A string literal, e.g., 'foo', is always a canonical string. The Virtual Machine has an internal table of canonical strings, such that there are no two canonical strings with the same sequence of characters. Hence, identity comparison can be used as equality on canonical strings. Self's identity comparison message is ==, just like Smalltalk. Canonical strings cannot be modified.

To do string processing, you can make mutable strings from canonical strings by sending copyMutable.

Mutable strings respond to at:Put:, first:, etc.

Most of the useful operations on strings are defined in traits string. There you will find methods to do simple parsing, evaluating strings as Self expressions, pattern matching, ordering, and many other things.

One unusual feature (especially for Smalltalk programmers): when you send at: to a string, the returned value is a one-element string! There are no distinct character objects.