lib/perl5/5.8.8/ExtUtils/NOTES

   1 The Simplified MakeMaker class hierarchy
   2 ****************************************
   3
   4 What most people need to know.
   5
   6 (Subclasses on top.)
   7
   8                MY
   9                 |
  10         ExtUtils::MakeMaker
  11                 |
  12         ExtUtils::MM_{Current OS}
  13                 |
  14         ExtUtils::MM_Unix
  15                 |
  16         ExtUtils::MM_Any
  17
  18 The object actually used is of the class MY which allows you to
  19 override bits of MakeMaker inside your Makefile.PL by declaring
  20 MY::foo() methods.
  21
  22
  23 The Real MakeMaker class hierarchy
  24 **********************************
  25
  26 You wish it was that simple.
  27
  28 Here's how it really works.
  29
  30                PACK### (created each call to ExtUtils::MakeMaker->new)
  31                     .                       |
  32                  (mixin)                    |
  33                     .                       |
  34         MY (created by ExtUtils::MY)        |
  35         |                                   |
  36         ExtUtils::MY         MM (created by ExtUtils::MM)
  37                    |          |
  38                    ExtUtils::MM
  39                     |     |   |-----------------------
  40                     |     |                          |
  41     ExtUtils::Liblist     ExtUtils::MakeMaker        |
  42           |                                          |
  43     ExtUtils::Liblist::Kid                           |
  44                                                      |
  45                                                      |
  46                                                      |
  47                                     ExtUtils::MM_{Current OS} (if necessary)
  48                                             |
  49                                     ExtUtils::MM_Unix
  50                                             |
  51                                     ExtUtils::MM_Any
  52
  53
  54 NOTE: Yes, this is a mess.  See
  55 http://archive.develooper.com/makemaker@perl.org/msg00134.html
  56 for some history.
  57
  58 NOTE: When ExtUtils::MM is loaded it chooses a superclass for MM from
  59 amongst the ExtUtils::MM_* modules based on the current operating
  60 system.
  61
  62 NOTE: ExtUtils::MM_{Current OS} represents one of the ExtUtils::MM_*
  63 modules except ExtUtils::MM_Any chosen based on your operating system.
  64
  65 NOTE: The main object used by MakeMaker is a PACK### object, *not*
  66 ExtUtils::MakeMaker.  It is, effectively, a subclass of MY,
  67 ExtUtils::Makemaker, ExtUtils::Liblist and ExtUtils::MM_{Current OS}
  68
  69 NOTE: The methods in MY are simply copied into PACK### rather than
  70 MY being a superclass of PACK###.  I don't remember the rationale.
  71
  72 NOTE: ExtUtils::Liblist should be removed from the inheritence hiearchy
  73 and simply be called as functions.
  74
  75 NOTE: Modules like File::Spec and Exporter have been omitted for clarity.
  76
  77
  78 The MM_* hierarchy
  79 ******************
  80
  81                                MM_Win95   MM_NW5
  82                                     \      /
  83 MM_BeOS  MM_Cygwin  MM_OS2  MM_VMS  MM_Win32  MM_DOS  MM_UWIN
  84       \        |      |         |        /      /      /
  85        ------------------------------------------------
  86                            |       |
  87                         MM_Unix    |
  88                               |    |
  89                               MM_Any
  90
  91 NOTE: Each direct MM_Unix subclass is also an MM_Any subclass.  This
  92 is a temporary hack because MM_Unix overrides some MM_Any methods with
  93 Unix specific code.  It allows the non-Unix modules to see the
  94 original MM_Any implementations.
  95
  96 NOTE: Modules like File::Spec and Exporter have been omitted for clarity.