Add QAST::VarWithFallback, a way to give a handful of variables a fal…

…lback way to do a lookup should the initial lookup return null. For use of things like contextuals, or when the fallback is to throw an error.
Raku · Aug 7, 2012 · 6849356 · 6849356
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commit 6849356
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diff --git a/src/QAST/VarWithFallback.nqp b/src/QAST/VarWithFallback.nqp
@@ -0,0 +1,4 @@
+class QAST::VarWithFallback is QAST::Var {
+    has $!fallback;
+    method fallback(*@value) { $!fallback := @value[0] if @value; $!fallback }
+}
diff --git a/tools/build/Makefile.in b/tools/build/Makefile.in
@@ -82,6 +82,7 @@ QAST_SOURCES = \
   src/QAST/WVal.nqp \
   src/QAST/Want.nqp \
   src/QAST/Var.nqp \
+  src/QAST/VarWithFallback.nqp \
   src/QAST/Op.nqp \
   src/QAST/VM.nqp \
   src/QAST/Stmts.nqp \