Makefile::AST::EvaluatUser)Contributed Perl DocumenMakefile::AST::Evaluator(3)NAMEMakefile::AST::Evaluator - Evaluator and runtime for Makefile::AST
instances
SYNOPSIS
use Makefile::AST::Evaluator;
$Makefile::AST::Evaluator::JustPrint = 0;
$Makefile::AST::Evaluator::Quiet = 1;
$Makefile::AST::Evaluator::IgnoreErrors = 1;
$Makefile::AST::Evaluator::AlwaysMake = 1;
$Makefile::AST::Evaluator::Question = 1;
# $ast is a Makefile::AST instance:
my $eval = Makefile::AST::Evaluator->new($ast);
Makefile::AST::Evaluator->add_trigger(
firing_rule => sub {
my ($self, $rule, $ast_cmds) = @_;
my $target = $rule->target;
my $colon = $rule->colon;
my @normal_prereqs = @{ $rule->normal_prereqs };
# ...
}
);
$eval->set_required_target($user_makefile)
$eval->make($goal);
DESCRIPTION
This module implementes an evaluator or a runtime for makefile ASTs
represented by Makefile::AST instances.
It "executes" the specified GNU make AST by the GNU makefile semantics.
Note that, "execution" not necessarily mean building a project tree by
firing makefile rule commands. Actually you can defining your own
triggers by calling the add_trigger method. (See the "SYNOPSIS" for
examples.) In other words, you can do more interesting things like
plotting the call path tree of a Makefile using Graphviz, or
translating the original makefile to another form (like what the
makesimple script does).
It's worth mentioning that, most of the construction algorithm for
topological graph s (including implicit rule application) have already
been implemented in Makefile::AST and its child node classes.
CONFIGURE VARIABLES
This module provides several package variables (i.e. static class
variables) for controlling the behavior of the evaluator.
Particularly the user needs to set the $AlwaysMake variable to true and
$Question to true, if she wants to use the evaluator to do special
tasks like plotting dependency graphs and translating GNU makefiles to
other format.
Setting $AlwaysMake to true will force the evaluator to ignore the
timestamps of external files appeared in the makefiles while setting
$Question to true will prevent the evaluator from executing the shell
commands specified in the makefile rules.
Here's the detailed listing for all the config variables:
$Question
This variable corresponds to the command-line option "-q" or
<--question> in GNU make. Its purpose is to make the evaluator
enter the "questioning mode", i.e., a mode in which "make" will
never try executing rule commands unless it has to, "and" echoing
is suppressed at the same time.
$AlwaysMake
This variable corresponds to the command-line option "-B" or
"--always-make". It forces re-constructing all the rule's targets
related to the goal, ignoring the timestamp or existence of
targets' dependencies.
$Quiet
It corresponds to GNU make's command-line option "-s", "--silent",
or "--quiet". Its effect is to cancel the echoing of shell commands
being executed.
$JustPrint
This variable corresponds to GNU make's command line option "-n",
"--just-print", "--dry-run", or "--recon". Its effect is to print
out the shell commands requiring execution but without actually
executing them.
$IgnoreErrors
This variable corresponds to GNU make's command line option "-i" or
"--ignore-errors"ieXXIt's used to ignore the errors of shell
commands being executed during the make process. The default
behavior is quitting as soon as a shell command without the "-"
modifier fails.
CLASS TRIGGERS
The "make_by_rule" method of this class defines a trigger named
"firing_rule" via the Class::Trait module. Everytime the "make_by_rule"
method reaches the trigger point, it will invoke the user's processing
handler with the following three arguments: the self object, the
Makefile::AST::Rule object, and the corresponding
"Makefile::AST::Command" object in the context.
By registering his own processing handlers for the "firing_rule"
trigger, the user's code can reuse the evaluator to do his own cool
things without traversing the makefile ASTs himself.
See the "SYNOPSIS" for code examples.
SVN REPOSITORY
For the very latest version of this script, check out the source from
http://svn.openfoundry.org/makefileparser/branches/gmake-db
<http://svn.openfoundry.org/makefileparser/branches/gmake-db>.
There is anonymous access to all.
AUTHOR
Agent Zhang "<agentzh@yahoo.cn>"
COPYRIGHT AND LICENSE
Copyright (c) 2007-2008 by Agent Zhang (agentzh).
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
SEE ALSO
Makefile::AST, Makefile::Parser::GmakeDB, pgmake-db, makesimple,
Makefile::DOM.
perl v5.14.1 2008-03-16 Makefile::AST::Evaluator(3)
