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Re^5: dynamic loading modules

by Anonymous Monk
on Sep 03, 2012 at 17:04 UTC ( #991482=note: print w/ replies, xml ) Need Help??


in reply to Re^4: dynamic loading modules
in thread dynamic loading modules

then must be some easy, clear way to handle this. without having to know the internals of every package.

Yes there is, its called abstraction, see Re^3: code that runs (and works) on both Linux and Win32


Comment on Re^5: dynamic loading modules
Re^6: dynamic loading modules
by sdetweil (Sexton) on Sep 03, 2012 at 17:27 UTC
    well, that requires learning ANOTHER pile of function..

    but I have my answer.. SOMETHING tells the compiler things are different..

    load 'package' value = package::function(); vs use Package::function; value = Package::Function;
    and maybe its just my mis understanding
    the value = is the same. the use vs load is to tell the runtime how to resolve.
    'use' means compiled in to some internal table,
    'load' means dynamically added to the same table.

      Perhaps you should have a look at the source of File::Spec. Or perhaps not. Think about the following construct first:

      (Each code block represents a properly named file)

      package MyProject::OSSpecific::base; use strict; use warnings; sub niceOSName { my $class=shift; die "$class does not implement an OS specific niceOSName() method" +; } sub tempDir { die "I don't know how to find a temp directory"; } sub pathSep { return '/'; } sub installTo { die "Should not happen"; } # much more methods 1;
      package MyProject::OSSpecific::doslike; use strict; use warnings; use parent 'MyProject::OSSpecific::base'; sub tempDir { return 'c:\\temp'; } sub pathSep { return '\\'; } # much more methods 1;
      package MyProject::OSSpecific::dos; use strict; use warnings; use parent 'MyProject::OSSpecific::doslike'; use Some::DOS::Specific::Module; sub niceOSName { my $x=`command /c ver`; chomp $x; return $x; } sub installTo { return 'C:\myproject'; } 1;
      package MyProject::OSSpecific::MSWin32; use strict; use warnings; use parent 'MyProject::OSSpecific::doslike'; use Win32; sub niceOSName { return Win32::GetOSName(); } sub installTo { return 'C:\\Program Files\\MyProject'; } 1;
      package MyProject::OSSpecific::unixlike; use strict; use warnings; use parent 'MyProject::OSSpecific::base'; sub niceOSName { my $x=`uname -a`; chomp $x; return $x; } sub tempDir { return '/tmp'; } sub pathSep { return '/'; } # much more methods 1;
      package MyProject::OSSpecific::freebsd; use strict; use warnings; use parent 'MyProject::OSSpecific::unixlike'; use Something::Created::Only::For::FreeBSD; sub installTo { return '/usr/local/myproject'; } 1;
      package MyProject::OSSpecific::linux; use strict; use warnings; use parent 'MyProject::OSSpecific::unixlike'; use Something::Very::Linux::Specific; sub installTo { return '/opt/myproject'; } 1;
      And finally:
      packame MyProject::OSSpecific; use strict; use warnings; use parent 'MyProject::OSSpecific::'.$^O; # <-- this is the most impor +tant trick here. 1;
      In your code:
      use strict; use warnings; use MyProject::OSSpecific; print "This program should be installed to ",MyProject::OSSpecific->in +stallTo(),"\n";

      Alexander

      --
      Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)

      well, that requires learning ANOTHER pile of function.

      Well, it requires learning substantially less than your current approach :) just copy/paste, it will work, all your problems will disappear

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