makerule

Prototype: makerule(target, sources)

Return type: boolean

Description: Evaluates whether a target file needs to be built or rebuilt from one or more sources files.

The function is provided to emulate the semantics of the Unix make program.

In a traditional Makefile, rules take the form

 target: source1 source2 ..
 (tab) commands

The top line evaluates to a predicate for executing a number of commands, which is true if the target file does not exist, or if any of the sources dependencies in the list has been changed since the target was last built.

The makerule function emulates the same semantics and sets a class if the target needs to be built or rebuit, i.e. if the top line of an equivalent makefile is true.

Arguments:

• target: string, in the range: "?(/.*)
• sources: string, in the range: .*

The sources argument may be either a scalar or a list reference. If the sources argument is the name of a list variable, then the entire list of sources is used to determine whether the target needs rebuilding.

Example:

classes:

 "build_me" expressions => makerule("/tmp/target", "/tmp/source.c");

commands:

   build_me::

      "/usr/bin/gcc -o /tmp/target /tmp/source.c";