probably aren't useful, but if you really want to push GNU Make syntax to its limits try this:
+:=+
Yes, that defines a variable called + containing a +.
Paul's warning
When I first blogged about some of this, I received the following warning from Paul Smith (the maintainer of GNU Make):
I don't recommend using a space as a variable name. I've toyed with the idea of allowing some special syntactic sugar for user-defined functions, that would allow you to omit the $(call ...) prefix and just invoke the user-defined function directly, like:
$(my-func arg1, arg2)
Obviously the way this works is that if make detects a space in the variable name, it would assume that it is a user-defined function. If this were to happen I'd probaby make whitespace in variable names illegal, just to cut down on confusion and bizarre misbehaviors.
OK, I'll be careful.
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About the author
John Graham-Cumming is Co-Founder at Electric Cloud, Inc . Prior to joining Electric Cloud, John was a Venture Consultant with Accel Partners, VP of Internet Technology at Interwoven, Inc. (IWOV), VP of Engineering at Scriptics Corporation (acquired by Interwoven), and Chief Architect at Optimal Networks, Inc. John holds BA and MA degrees in Mathematics and Computation and a Doctorate in Computer Security from Oxford University. John is the creator of the highly acclaimed open source POPFile project. He also holds two patents in network analysis and has others pending.
