1Workflow::Condition::NeUssteerd(C3o)ntributed Perl DocumWeonrtkaftlioown::Condition::Nested(3)
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6 Workflow::Condition::Nested - Evaluate nested workflow conditions
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9 This documentation describes version 1.51 of this package
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12 Typically, the workflow conditions are evaluated directly by the
13 framework in Workflow::State when the action is evaluated. This module
14 allows a workflow condition to contain nested conditions that are
15 evaluated directly rather than via separate workflow actions.
16 This allows the workflow to be designed to group multiple conditions
18 and perform advanced operations like an OR comparision of multiple
19 conditions with "greedy" evaluation (as opposed to "lazy" evaluation).
20 A usage example might be a case where 3 of 5 possible approvals are
22 needed for an action to be allowed. The "Greedy OR" condition would
23 define the list of conditions to be evaluated. After checking each
24 condition, it would return the total number of successes. The result is
25 then checked against the number needed, returning the boolean value
26 needed by Workflow::State.
27 Note: This class is not used directly, but subclassed by your class
29 that implements the "evaluate()" method and calls methods declared
30 here.
31
33 In condition.xml:
34 <condition name="cond1" ... />
36 <condition name="cond2" ... />
37 <condition name="cond3" ... />
38 <condition name="cond4" ... />
39 <condition name="cond5" ... />
40 <condition name="count_approvals" class="Workflow::Condition::GreedyOR">
42 <param name="condition" value="cond1" />
43 <param name="condition" value="cond2" />
44 <param name="condition" value="cond3" />
45 <param name="condition" value="cond4" />
46 <param name="condition" value="cond5" />
47 </condition>
48 <condition name="check_approvals" class="Workflow::Condition::CheckReturn">
50 <param name="condition" value="count_approvals" />
51 <!-- operator "ge" means: greater than or equal to -->
52 <param name="operator" value="ge" />
53 <param name="argument" value="$context->{approvals_needed}" />
54 </condition>
55 In workflow.xml:
57 <state name="CHECK_APPROVALS" autorun="yes">
59 <action name="null_1" resulting_state="APPROVED">
60 <condition name="check_approvals" />
61 </action>
62 <action name="null_2" resulting_state="REJECTED">
63 <condition name="!check_approvals" />
64 </action>
65 </state>
66
68 This wicked hack runs the condition half-outside of the Workflow
69 framework. If the Workflow internals change, this may break.
70 $self->evaluate_condition( $WORKFLOW, $CONDITION_NAME )
72 The child object class that subclasses this object calls this method to
73 evaluate a nested condition.
74 If the condition name starts with an '!', the result of the condition
76 is negated. Note that a side-effect of this is that the return value of
77 the nested condition is ignored. Only the negated boolean-ness is
78 preserved.
79 This does implement a trick that is not a convention in the underlying
81 Workflow library. By default, workflow conditions throw an error when
82 the condition is false and just return when the condition is true. To
83 allow for counting the true conditions, we also look at the return
84 value here. If a condition returns zero or an undefined value, but did
85 not throw an exception, we consider it to be '1'. Otherwise, we
86 consider it to be the value returned.
87
89 Copyright (c) 2004-2021 Chris Winters. All rights reserved.
90 This library is free software; you can redistribute it and/or modify it
92 under the same terms as Perl itself.
93 Please see the LICENSE
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97 Please see Workflow
98perl v5.32.1 2021-01-31 Workflow::Condition::Nested(3)