make-needvar

A can test whether a variable holds a non-empty value in the current process. With GNU make, any variable can be checked. With BSD make, you must set the needvars variable to the list of variables that can be checked. and elegant way to test whether a variable is defined in your make run. Works with both GNU Make and BSD Make.

Overview

With make-needvar you can test whether a variable holds a non-empty value in the current make process. This is done with a target

Usage

Include mk/needvar.mk at the top level in your project.

include mk/needvar.mk

For BSD make, define the variables you want to check:

needvars = foo bar baz

Check that a variable is set to a non-empty value in a target:

mytarget: needvar.X
    ...

That's it!

Features

• Works with both GNU Make and BSD Make
• Simple implementation
• Easy to integrate into existing projects

Installation

1. Copy the mk/ directory to your project, which contains:

   • mk/needvar.mk
   • mk/needvar.gnu.mk
   • mk/needvar.bsd.mk

2. Add this line to your Makefile:

include mk/needvar.mk

That's it! Now running make will show help for all documented targets.

Example

The included example Makefile demonstrates the features:

needvars = a b c
foo: needvar.a
    echo "this is foo, now with $(a)"

Public Domain

This project is released into the public domain. Feel free to use it however you like!

Contributing

Feel free to open issues or submit pull requests on GitHub.