Is there a way to seek through a file without loading the whole thing into an array?

Question

This works:

f = File.new(\"myfile\").readlines
f[0] #=> \"line 1\"
f[21] #=> \"line 22\"

But what if I have a very large file, and on

Answer 1

Don't ignore the IO class. IO::foreach is one of those methods that returns an Enumerator, and can be lazily evaluated.

IO#each_line is also another one that will return an Enumerator.

In Ruby 2.0 we can call .lazy and use those methods, except for zip and cycle, that allow us to traverse the enumeration without bringing the whole file into memory.