(make.info.gz) Static versus Implicit

 
 4.12.2 Static Pattern Rules versus Implicit Rules
 -------------------------------------------------
 
 A static pattern rule has much in common with an implicit rule defined
 as a pattern rule ( Defining and Redefining Pattern Rules Pattern
 Rules.).  Both have a pattern for the target and patterns for
 constructing the names of prerequisites.  The difference is in how
 `make' decides _when_ the rule applies.
 
    An implicit rule _can_ apply to any target that matches its pattern,
 but it _does_ apply only when the target has no commands otherwise
 specified, and only when the prerequisites can be found.  If more than
 one implicit rule appears applicable, only one applies; the choice
 depends on the order of rules.
 
    By contrast, a static pattern rule applies to the precise list of
 targets that you specify in the rule.  It cannot apply to any other
 target and it invariably does apply to each of the targets specified.
 If two conflicting rules apply, and both have commands, that's an error.
 
    The static pattern rule can be better than an implicit rule for these
 reasons:
 
    * You may wish to override the usual implicit rule for a few files
      whose names cannot be categorized syntactically but can be given
      in an explicit list.
 
    * If you cannot be sure of the precise contents of the directories
      you are using, you may not be sure which other irrelevant files
      might lead `make' to use the wrong implicit rule.  The choice
      might depend on the order in which the implicit rule search is
      done.  With static pattern rules, there is no uncertainty: each
      rule applies to precisely the targets specified.
Info Catalog
(make.info.gz) Static Usage
(make.info.gz) Static Pattern
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