Question

What’s a simple way to implement file inclusion in Ruby, e.g. if a text file includes {{{stuff.txt}}}, the contents of stuff.txt is included in-line. I thought maybe something like this:

cat prog | ruby -pe 'gsub /{{{.+}}}/, File.open("$0").read'

… with eval() involved, but can’t get it to work.

Answer 1

If you’d like to do it straight from the command line, try

cat prog | ruby -pe '$_.gsub!(/{{{(.+?)}}}/) { File.read $1 }'

As pointed out by Alex D, .+ is greedy and matches as many characters as it can. On the other hand, .+? tries to match as few characters as possible.

Ruby’s command line -p expects you to update the value of the $_ variable. Hence usage of mutating gsub! instead of gsub, which makes a copy. The same result could be achieved by using -n.

cat prog |  ruby -ne 'puts $_.gsub(/{{{(.+?)}}}/) {  File.read $1 }'