Author: ruoso
Date: 2009-03-13 15:21:56 +0100 (Fri, 13 Mar 2009)
New Revision: 25819
Modified:
docs/Perl6/Spec/S07-iterators.pod
Log:
[spec] Add Iterator::Unshift to S07
Modified: docs/Perl6/Spec/S07-iterators.pod
===================================================================
--- docs/Perl6/Spec/S07-iterators.pod 2009-03-13 14:06:26 UTC (rev 25818)
+++ docs/Perl6/Spec/S07-iterators.pod 2009-03-13 14:21:56 UTC (rev 25819)
@@ -163,6 +163,22 @@
original order or if it wasn't consumed. In that case, it should fail
with UnorderedPushBackException or BadPushBackException.
+=head1 The Iterator::Unshift Role
+
+This role defines an iterator that can receive new elements in the top
+of the stack, it works like pushback, but it should be able to store
+objects that are completely new to this stream. Either by being backed
+by a mutable list or by providing a local stack. This role implies
+Iterator::PushBack, where pushback will be handled by unshift.
+
+The purpose of defining two different Roles is to give the user the
+"expect to fail" or "expect to succeed" semantics.
+
+=head2 method unshift($value) {}
+
+This unshifts $value either to the backed list or to a local stack of
+the iterator.
+
=head1 Auxiliary Implementations
Perl's built-ins require that a number of auxiliary types.
