From ba117ef7e9b2f7f2fbec62a9fcfe371a68024769 Mon Sep 17 00:00:00 2001
From: Amaury Forgeot d'Arc <amauryfa@gmail.com>
Date: Fri, 10 Sep 2010 21:39:53 +0000
Subject: #4617: Previously it was illegal to delete a name from the local
 namespace if it occurs as a free variable in a nested block.  This limitation
 of the compiler has been lifted, and a new opcode introduced (DELETE_DEREF).

This sample was valid in 2.6, but fails to compile in 3.x without this change::

   >>> def f():
   ...     def print_error():
   ...        print(e)
   ...     try:
   ...        something
   ...     except Exception as e:
   ...        print_error()
   ...        # implicit "del e" here


This sample has always been invalid in Python, and now works::

   >>> def outer(x):
   ...     def inner():
   ...        return x
   ...     inner()
   ...     del x

There is no need to bump the PYC magic number: the new opcode is used
for code that did not compile before.
---
 Include/opcode.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'Include')

diff --git a/Include/opcode.h b/Include/opcode.h
index 1114c9386a8..6b1094449e9 100644
--- a/Include/opcode.h
+++ b/Include/opcode.h
@@ -123,6 +123,7 @@ extern "C" {
 #define LOAD_CLOSURE    135     /* Load free variable from closure */
 #define LOAD_DEREF      136     /* Load and dereference from closure cell */ 
 #define STORE_DEREF     137     /* Store into cell */ 
+#define DELETE_DEREF    138     /* Delete closure cell */ 
 
 /* The next 3 opcodes must be contiguous and satisfy
    (CALL_FUNCTION_VAR - CALL_FUNCTION) & 3 == 1  */
-- 
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