Check in a stable (working) version before next round of tweaks.

Changes include:
 - Move default layers code out of doio.c and into perlio.c
 - Single routine for parsing layer specification strings.
 - Skeleton support for demand loading of layers
 - Core-dump avoidance if PERLIO environment specifies loadable layer
   (does not _work_ as need IO to load and need load to do IO ...)

p4raw-id: //depot/perlio@9313

1 files changed, 26 insertions, 0 deletions

diff --git a/lib/PerlIO.pm b/lib/PerlIO.pm
new file mode 100644
index 0000000000..c5ce016db4
--- /dev/null
+++ b/lib/PerlIO.pm
@@ -0,0 +1,26 @@
+package PerlIO;
+
+# Map layer name to package that defines it
+my %alias = (encoding => 'Encode');
+
+sub import
+{
+ my $class = shift;
+ while (@_)
+  {
+   my $layer = shift;
+   if (exists $alias{$layer})
+    {
+     $layer = $alias{$layer}
+    }
+   else
+    {
+     $layer = "${class}::$layer";
+    }
+   eval "require $layer";
+   warn $@ if $@;
+  }
+}
+
+1;
+__END__