Building a Large String a Piece at a Time

Category: Coding

Problem

You need to build a large string a piece at a time.

Ingredients

strings, string concatenation

Recipe

Simply concatenate the pieces together. For example:

s = ""
while (false isnt piece = NextPiece())
    s $= piece

Note: If you have the pieces in an object, consider using object.Join

Discussion

This recipe is almost too simple to include. The reason it's here, is that most other languages with immutable strings (e.g. Java, Python, Lua) specifically tell you not to do it this way. This is because, with a normal string implementation, every time you concatenate, a new string is created and the contents of the two strings is copied into it. In this situation, building a large string is very inefficient. Java recommends using a StringBuffer instead of normal strings. Python recommends creating a list of pieces and then concatenating them. A Lua technical notes suggests using a somewhat complicated stack of string pieces using a "tower of hanoi" system. All this just to build a string?

With Suneido you don't have to worry about it. Suneido's string implementation delays concatenation until it is necessary, building a linked list of pieces instead. This is completely transparent - done for you automatically.