Makefile::AST::Evaluator(3pm)

1Makefile::AST::EvaluatoUrs(e3r)Contributed Perl DocumentMaatkieofnile::AST::Evaluator(3)
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NAME

6       Makefile::AST::Evaluator - Evaluator and runtime for Makefile::AST
7       instances
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SYNOPSIS

10           use Makefile::AST::Evaluator;
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12           $Makefile::AST::Evaluator::JustPrint = 0;
13           $Makefile::AST::Evaluator::Quiet = 1;
14           $Makefile::AST::Evaluator::IgnoreErrors = 1;
15           $Makefile::AST::Evaluator::AlwaysMake = 1;
16           $Makefile::AST::Evaluator::Question = 1;
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18           # $ast is a Makefile::AST instance:
19           my $eval = Makefile::AST::Evaluator->new($ast);
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21           Makefile::AST::Evaluator->add_trigger(
22               firing_rule => sub {
23                   my ($self, $rule, $ast_cmds) = @_;
24                   my $target = $rule->target;
25                   my $colon = $rule->colon;
26                   my @normal_prereqs = @{ $rule->normal_prereqs };
27                   # ...
28               }
29           );
30           $eval->set_required_target($user_makefile)
31           $eval->make($goal);
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DESCRIPTION

34       This module implementes an evaluator or a runtime for makefile ASTs
35       represented by Makefile::AST instances.
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37       It "executes" the specified GNU make AST by the GNU makefile semantics.
38       Note that, "execution" not necessarily mean building a project tree by
39       firing makefile rule commands. Actually you can defining your own
40       triggers by calling the add_trigger method. (See the "SYNOPSIS" for
41       examples.) In other words, you can do more interesting things like
42       plotting the call path tree of a Makefile using Graphviz, or
43       translating the original makefile to another form (like what the
44       makesimple script does).
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46       It's worth mentioning that, most of the construction algorithm for
47       topological graph s (including implicit rule application) have already
48       been implemented in Makefile::AST and its child node classes.
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CONFIGURE VARIABLES

51       This module provides several package variables (i.e. static class
52       variables) for controlling the behavior of the evaluator.
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54       Particularly the user needs to set the $AlwaysMake variable to true and
55       $Question to true, if she wants to use the evaluator to do special
56       tasks like plotting dependency graphs and translating GNU makefiles to
57       other format.
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59       Setting $AlwaysMake to true will force the evaluator to ignore the
60       timestamps of external files appeared in the makefiles while setting
61       $Question to true will prevent the evaluator from executing the shell
62       commands specified in the makefile rules.
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64       Here's the detailed listing for all the config variables:
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66       $Question
67           This variable corresponds to the command-line option "-q" or
68           <--question> in GNU make. Its purpose is to make the evaluator
69           enter the "questioning mode", i.e., a mode in which "make" will
70           never try executing rule commands unless it has to, "and" echoing
71           is suppressed at the same time.
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73       $AlwaysMake
74           This variable corresponds to the command-line option "-B" or
75           "--always-make". It forces re-constructing all the rule's targets
76           related to the goal, ignoring the timestamp or existence of
77           targets' dependencies.
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79       $Quiet
80           It corresponds to GNU make's command-line option "-s", "--silent",
81           or "--quiet". Its effect is to cancel the echoing of shell commands
82           being executed.
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84       $JustPrint
85           This variable corresponds to GNU make's command line option "-n",
86           "--just-print", "--dry-run", or "--recon". Its effect is to print
87           out the shell commands requiring execution but without actually
88           executing them.
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90       $IgnoreErrors
91           This variable corresponds to GNU make's command line option "-i" or
92           "--ignore-errors"ieXXIt's used to ignore the errors of shell
93           commands being executed during the make process. The default
94           behavior is quitting as soon as a shell command without the "-"
95           modifier fails.
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CLASS TRIGGERS

98       The "make_by_rule" method of this class defines a trigger named
99       "firing_rule" via the Class::Trait module. Everytime the "make_by_rule"
100       method reaches the trigger point, it will invoke the user's processing
101       handler with the following three arguments: the self object, the
102       Makefile::AST::Rule object, and the corresponding
103       "Makefile::AST::Command" object in the context.
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105       By registering his own processing handlers for the "firing_rule"
106       trigger, the user's code can reuse the evaluator to do his own cool
107       things without traversing the makefile ASTs himself.
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109       See the "SYNOPSIS" for code examples.
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SVN REPOSITORY

112       For the very latest version of this script, check out the source from
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114       <http://svn.openfoundry.org/makefileparser/branches/gmake-db>.
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116       There is anonymous access to all.
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AUTHOR

119       Agent Zhang "<agentzh@yahoo.cn>"
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COPYRIGHT AND LICENSE

122       Copyright (c) 2007-2008 by Agent Zhang (agentzh).
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124       This library is free software; you can redistribute it and/or modify it
125       under the same terms as Perl itself.
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