[cmake-developers] [CMake 0015231]: find_package: should be a simple way to alter the order of the config/module lookups

[Mantis Bug Tracker]

The following issue has been SUBMITTED. 
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http://www.cmake.org/Bug/view.php?id=15231 
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Reported By:                Charles Karney
Assigned To:                
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Project:                    CMake
Issue ID:                   15231
Category:                   CMake
Reproducibility:            N/A
Severity:                   feature
Priority:                   normal
Status:                     new
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Date Submitted:             2014-10-31 12:31 EDT
Last Modified:              2014-10-31 12:31 EDT
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Summary:                    find_package: should be a simple way to alter the
order of the config/module lookups
Description: 
As we are integrating cmake more and more into our environment, it is
clear how much superior the config-mode for find_package is compared to
the module-mode.  As a result, our top-level CMakeLists.txt contains
several occurrences of the following pattern

  find_package (PROJ4 CONFIG QUIET)
  if (NOT PROJ4_FOUND)
    find_package (PROJ4 MODULE REQUIRED)
  endif ()

Request 1: Add

  MODULE_FIRST
  CONFIG_FIRST

options to find_package, meaning do the module lookup first (the default
but see next) or the config lookup first.  (These options complement the
MODULE and CONFIG options.)  So the find_package invocation above
becomes

  find_package (PROJ4 CONFIG_FIRST REQUIRED)

Request 2: Add a global variable, e.g., CMAKE_FIND_PACKAGE_PREFER_CONFIG
(default OFF) to specify the default lookup order.  Thus if I've worked
to get all my dependent packages with config-mode support, I can invoke
cmake with

  cmake -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=ON ..

without having to edit the CMakeLists.txt file.

Finally a comment: the advice (not sure where from) that our current
pattern can be shortened to

  find_package (PROJ4 NO_MODULE QUIET)
  find_package (PROJ4 MODULE)

seems not to hold in all cases.  If you think this should work, let me
know and I will look for a counter-example.
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Issue History 
Date Modified    Username       Field                    Change               
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2014-10-31 12:31 Charles Karney New Issue                                    
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