Broken perl configuration

[Jan Stary]

On Feb 23 12:43:10, pixilla at macports.org wrote:
> 
> On Feb 23, 2013, at 11:49 AM, Jan Stary wrote:
> 
> > On Feb 21 11:05:23, dluke at geeklair.net wrote:
> >> On Feb 21, 2013, at 10:05 AM, Bruce Miller <bruce.miller at nist.gov> wrote:
> >>> With MacPort's perl 5.12, the executable is installed in
> >>> /opt/local/libexec/perl5.12/sitebin
> >>> which is *NOT* where people expect to find programs.
> >>> And it's NOT a directory people want to maintain in
> >>> their $PATH.
> >> 
> >> why? Why would people care whether they have /opt/local/bin or /opt/local/libexec/perl5.12/sitebin or /my/nonstandard/macports/prefix/bin in their $PATH?
> > 
> > People will care that they
> > (1) have to tweak their PATH at all
> > (2) have to pollute with /opt/local/libexec/version-du-jour-123
> > and keep an eye on what the exact verion is this week.
> > 
> >>> The reason for the configuration change
> >>> is to achieve the noble goal of being able
> >>> to install multiple versions of Perl, and
> >>> multiple versions of software running under
> >>> those Perls.  
> > 
> > Please excuse my Perl ignorance - what would be
> > a realistic scenario for having multiple versions
> > of Perl installed, and multiple version of Perl
> > software on top of those?
> 
> I believe there are cases where ports depend on perl modules
> that are only compatible with specific perl versions.

Could somebody please provide an example of such situation?