Here's the setup:

I have a system with a bunch of default packages installed.
I allow users to drop in newer versions of these packages to a well-known location on the disk (not in @INC).

I've defined a universal autoloader to redirect specific function calls to these newer versions... for example:

My::Package::foo() is a subroutine in the default install.
My::Package::foo() is a subroutine in the new version location.

The autoloader (simplified for this example): 
sub AUTOLOAD
{
    my $f = $AUTOLOAD;
    if( $f =~ /^(My(::[a-zA-Z0-9_]+)*)(::|->)([a-zA-Z0-9_]+)$/ )
    {
        my $pkg = $1;
        eval "require $pkg;";
    }
    if( $f =~ /^NEW::(.*)$/ )
    {
        my $func = $1;
        unshift( @INC, "/newpkgs" );
        return &{$func}(@_);
    }
    else
    {
        goto \&{$f};
        return;
    }
}

[download]
There are two problems with this, and I'm grasping at straws now :)

Problem 1: If anything causes My::Package to load before they call NEW::My::Package::foo(), it will use the older version because it was already loaded.

Problem 2: If anything causes the My::Package module to load from the /newpkgs location, subsequent calls to My::Package::foo() (without the NEW:: prefix) will use the new package and not the old one.

What I really need is a way to local the entire symbol table and then clear it out so that calling "NEW::Package::foo()" will load whatever requirements it has first from the /newpkgs location and falling back to the other paths in @INC... and after the call is over ensuring that the symbol table is back to the "before-I-called-NEW::My::Package::foo()" state.

Any suggestions? Many thanks in advance!

In reply to How can I (safely) use packages of the same name but different versions? by xevian

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.