behaviour of once in classes

Author: adaptiveoptics

doc/Language/traps.pod6

@@ -519,6 +519,17 @@ In this example, we essentially manually build a C<once> block by making a C<sta
 
 The main difference between using a C<state> variable like the above example and using a regular C<once> block is what scope the C<state> variable is in. The scope for the C<state> variable created by the C<once> block, is the same as where you put the block (imagine that the word 'C<once>' is replaced with a state variable and an C<if> to look at the variable). The example above using C<state> variables works because the variable is at the highest scope that will be repeated; whereas the example that has a C<once> block inside of a C<do>, made the variable within the C<do> block which is not the highest scope that is repeated.
 
+Using a C<once> block inside a class method will cause the once state to carry across all instances of that class.
+For example:
+
+    class A {
+        method sayit() { once say 'hi' }
+    }
+    my $a = A.new;
+    $a.sayit;      # says 'hi'
+    my $b = A.new;
+    $b.sayit;      # nothing
+
 =end pod
 
 # vim: expandtab shiftwidth=4 ft=perl6