Rules

• Sometimes you don’t want to write rules for every single file task … so use a rule.

  rule '.o' => ['.c'] do |t|
    sh %{cc #{t.source} -c -o #{t.name}}
  end

• When you need to build a file named "main.o"
  • And "main.o" doesn’t exist, But "main.c" does …
  • Then synthesize a file task to build "main.o" from "main.c"

 file "xyz.o" => ["xyz.c"] do |t|
    sh %{cc #{t.source} -c -o #{t.name}}
 end