Why isn't there a String#shift()?

Question

I'm working my way through Project Euler, and ran into a slightly surprising omission: There is no String#shift, unshift, push, or pop. I had assumed a String was considered a "sequential" object like an Array, since they share the ability to be indexed and iterated through, and that this would include the ability to easily change the beginning and ends of the object.

I know there are ways to create the same effects, but is there a specific reason that String does not have these methods?

Answer 1

Strings don't act as an enumerable object as of 1.9, because it's considered too confusing to decide what it'd be a list of:

• A list of characters / codepoints?
• A list of bytes?
• A list of lines?

Answer 2

Not being a Ruby contributor, I can't speak to their design goals, but from experience, I don't think that strings are regarded as 'sequential' objects; they're mutable in ways that suggest sequential behaviour, but most of the time they're treated atomically.

Case in point: in Ruby 1.9, String no longer mixes in Enumerable.