This file contains various notes about the Perl support.
( $Id: README.txt,v 1.1 2002/04/07 14:54:03 leif Exp $ )
The semantics of Perl's embedding interface seems to be in flux, changing
a bit between versions; the most substantial problem with this that I've
noticed is that Perl 5.6.0 and 5.6.1 have a tendency to cause a core
dump when trying to create a second instance of a Perl interpreter
from Pike. This doesn't seem to happen with either Perl 5.005_03 or
5.7.3, however, even when compiling with the exact same Pike-to-Perl
glue code that failed for Perl 5.6.x.
A Perl compiled with the Perl thread support causes things to change
in how certain include files behave, which in turn can cause the
compilation of Pike with Perl support to fail with errors like "`thr'
undeclared" when expanding the Perl dSP macro. Searching some mail
archives yields suggestions that "`thr' undeclared" errors can be
cured by adding a dTHR, but dTHR is the first thing done by the dSP
macro, and adding an explicit dTHR right before the dSP did (predictably)
not help when I tried it. And I haven't had the time to investigate
this very much.
Using the Pike Perl support with Perls where MULTIPLICITY is enabled
is largely uncharted territory, although it should work in theory.
RUNNING PIKE INTERACTIVELY:
When running Pike interactively, remember that new versions of the
interactive frontend Hilfe keeps a history of results of evaluation of
previous commands. This means that objects that are referenced from
the history, in particular the Perl interpreter object, are not freed
until they fall out of the history list. Since there can only be one
Perl interpreter object alive at the same time (unless Perl has been
compiled with MULTIPLICITY enabled; see the note about this above),
this may force you to empty the history list or disable the history
feature if you need to create a new Perl interpreter object during the
same Hilfe session.