Author: lwall
Date: 2009-09-03 07:18:16 +0200 (Thu, 03 Sep 2009)
New Revision: 28175
Modified:
docs/Perl6/Spec/S02-bits.pod
Log:
[S02] some clarification of $*foo searching
Modified: docs/Perl6/Spec/S02-bits.pod
===================================================================
--- docs/Perl6/Spec/S02-bits.pod 2009-09-03 00:00:53 UTC (rev 28174)
+++ docs/Perl6/Spec/S02-bits.pod 2009-09-03 05:18:16 UTC (rev 28175)
@@ -14,7 +14,7 @@
Created: 10 Aug 2004
Last Modified: 2 Sep 2009
- Version: 177
+ Version: 178
This document summarizes Apocalypse 2, which covers small-scale
lexical items and typological issues. (These Synopses also contain
@@ -2110,16 +2110,17 @@
=item *
The C<CONTEXT> pseudo-package is just like C<CALLER> except that
-it starts in the current dynamic scope and from there
-scans outward through all dynamic scopes until it finds a
-contextual variable of that name in that context's lexical scope.
-(Use of C<$*FOO> is equivalent to C<< CONTEXT::<$FOO> >> or C<< $CONTEXT::FOO
>>.)
-If after scanning all the lexical scopes of each dynamic scope,
-there is no variable of that name, it looks in the C<GLOBAL> package followed
-by the C<PROCESS> package.
-If there is no such package variable,
-it then looks in C<< CONTEXT::<%ENV> >> for the identifier of the variable,
-which, if not overridden in a dynamic scope, finds C<< PROCESS::<%ENV> >>,
+it starts in the current dynamic scope and from there scans outward
+through all dynamic scopes until it finds a contextual variable of that
+name in that dynamic context's associated lexical pad. (This search
+is implied for variables with the C<*> twigil; hence C<$*FOO> is
+equivalent to C<< CONTEXT::<$*FOO> >>.) If, after scanning outward
+through all those dynamic scopes, there is no variable of that name
+in any immediately associated lexical pad, it looks in the C<GLOBAL>
+package followed by the C<PROCESS> package. If there is no such
+package variable, it then looks in C<< CONTEXT::<%*ENV> >> for the
+identifier of the variable, which, if not overridden in a dynamic
+scope, rescans outward and eventually finds C<< PROCESS::<%*ENV> >>,
that is, in the environment variables passed to program. If the
value is not found there, it returns failure. If the variable is
of the form C<$*FOO>, the complete environment value is returned. If it
@@ -2135,8 +2136,8 @@
my $*foo ::= CALLER::<$*foo>;
-The C<temp> maybe used without an initializer on a contextual variable
-to perform a similar operation:
+The C<temp> declarator may be used (without an initializer) on a
+contextual variable to perform a similar operation:
temp $*foo;
@@ -2147,6 +2148,13 @@
because you'd want to override it later and then forget the
changes at the end of the current dynamic scope.
+You may also use C<< OUTER::<$*foo> >> to mean you want to start the
+search in your outer lexical scope, but this will succeed only if
+that outer lexical scope also happens to be be one of your current
+I<dynamic> scopes. That is, the same search is done as with the bare
+C<$*foo>, but any "hits" are ignored until we've got to the C<OUTER>
+scope in our traversal.
+
The C<CONTEXT> package is primarily for internal overriding of contextual
information, modelled on how environmental variables work among
processes. Despite the fact that the C<CONTEXT> package reflects the
