Cognitive Consonance

When doing Groovy scripts I sometimes have the need to redirect the output of a part of the computation that is going to standard out.. A possible solution would be to open a new Writer and change the code to write to it (i.e. replacing all prints with newStream.prints), this, of course requires changing all prints, which is cumbersome and boring. There is a lazy alternative, using method references:

s = new PrintStream(new FileOutputStream("/tmp/myOut"))
def print = s.&print
print "a"
print = System.out.&print
print "b"

In this case the a is written to /tmp/myOut and b gets back to the standard output again. The big gain: all those prints in a script (and printlns) don’t need to be changed! Lazy me is happy.

Caveat: I would be careful in using this strategy a lot, it is be very easy to loose track of what is happening to the output. But it can be quite an expedient way to redirect prints on simple scripts.