Description: Evaluates whether a
target file needs to be built or
rebuilt from one or more
The function is provided to emulate the semantics of the Unix
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
target file does not exist, or if any of the
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.
sources argument may be either a scalar (indicating a single
source) or a list reference or a data container. If the
argument specifies a list, then the entire list of sources is used to
determine whether the target needs rebuilding.
classes: "build_me" expression => makerule("/tmp/target", "/tmp/source.c"); "build_me_ab" expression => makerule("/tmp/target", '["/tmp/source.a","/tmp/source.b"]' ); commands: build_me:: "/usr/bin/gcc -o /tmp/target /tmp/source.c";
History: The collecting function behavior was added in 3.9.
See also: About collecting functions.