Some more changes related to the new except syntax and semantics,

by Collin Winter.

Author: gvanrossum

Grammar/Grammar

@@ -79,7 +79,7 @@ try_stmt: ('try' ':' suite
 with_stmt: 'with' test [ with_var ] ':' suite
 with_var: 'as' expr
 # NB compile.c makes sure that the default except clause is last
-except_clause: 'except' [test ['as' test]]
+except_clause: 'except' [test ['as' NAME]]
 suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT
 
 # Backward compatibility cruft to support:

Include/Python-ast.h

@@ -322,7 +322,7 @@ struct _comprehension {
 
 struct _excepthandler {
         expr_ty type;
-        expr_ty name;
+        identifier name;
         asdl_seq *body;
         int lineno;
         int col_offset;
@@ -448,8 +448,8 @@ slice_ty ExtSlice(asdl_seq * dims, PyArena *arena);
 slice_ty Index(expr_ty value, PyArena *arena);
 comprehension_ty comprehension(expr_ty target, expr_ty iter, asdl_seq * ifs,
                                PyArena *arena);
-excepthandler_ty excepthandler(expr_ty type, expr_ty name, asdl_seq * body, int
-                               lineno, int col_offset, PyArena *arena);
+excepthandler_ty excepthandler(expr_ty type, identifier name, asdl_seq * body,
+                               int lineno, int col_offset, PyArena *arena);
 arguments_ty arguments(asdl_seq * args, identifier vararg, expr_ty
                        varargannotation, asdl_seq * kwonlyargs, identifier
                        kwarg, expr_ty kwargannotation, asdl_seq * defaults,

Lib/compiler/pycodegen.py

@@ -825,11 +825,33 @@ def visitTryExcept(self, node):
                 self.emit('POP_TOP')
             self.emit('POP_TOP')
             if target:
-                self.visit(target)
+                cleanup_body = self.newBlock()
+                cleanup_final = self.newBlock()
+                target_name = target[1]
+            
+                self.storeName(target_name)
+                self.emit('POP_TOP')
+                self.emit('SETUP_FINALLY', cleanup_final)
+                self.nextBlock(cleanup_body)
+                self.setups.push((TRY_FINALLY, cleanup_body))
+                self.visit(body)
+                self.emit('POP_BLOCK')
+                self.setups.pop()
+                self.emit('LOAD_CONST', None)
+                self.nextBlock(cleanup_final)
+                self.setups.push((END_FINALLY, cleanup_final))
+                
+                
+                self.emit('LOAD_CONST', None)
+                self.storeName(target_name)
+                self._implicitNameOp('DELETE', target_name)
+                
+                self.emit('END_FINALLY')
+                self.setups.pop()
             else:
                 self.emit('POP_TOP')
-            self.emit('POP_TOP')
-            self.visit(body)
+                self.emit('POP_TOP')
+                self.visit(body)
             self.emit('JUMP_FORWARD', end)
             if expr:
                 self.nextBlock(next)

Lib/compiler/transformer.py

@@ -988,16 +988,16 @@ def com_try_except_finally(self, nodelist):
         for i in range(3, len(nodelist), 3):
             node = nodelist[i]
             if node[0] == symbol.except_clause:
-                # except_clause: 'except' [expr [',' expr]] */
+                # except_clause: 'except' [expr ['as' NAME]] */
                 if len(node) > 2:
-                    expr1 = self.com_node(node[2])
+                    expr = self.com_node(node[2])
                     if len(node) > 4:
-                        expr2 = self.com_assign(node[4], OP_ASSIGN)
+                        expr_name = node[4]
                     else:
-                        expr2 = None
+                        expr_name = None
                 else:
-                    expr1 = expr2 = None
-                clauses.append((expr1, expr2, self.com_node(nodelist[i+2])))
+                    expr = expr_name = None
+                clauses.append((expr, expr_name, self.com_node(nodelist[i+2])))
 
             if node[0] == token.NAME:
                 if node[1] == 'else':

Parser/Python.asdl

@@ -97,7 +97,7 @@ module Python version "$Revision$"
 	-- TODO(jhylton): Figure out if there is a better way to handle
 	--                lineno and col_offset fields, particularly when
         --                ast is exposed to Python.
-	excepthandler = (expr? type, expr? name, stmt* body, int lineno,
+	excepthandler = (expr? type, identifier? name, stmt* body, int lineno,
 	                 int col_offset)
 
 	arguments = (arg* args, identifier? vararg, expr? varargannotation,

Python/Python-ast.c

@@ -1836,7 +1836,7 @@ comprehension(expr_ty target, expr_ty iter, asdl_seq * ifs, PyArena *arena)
 }
 
 excepthandler_ty
-excepthandler(expr_ty type, expr_ty name, asdl_seq * body, int lineno, int
+excepthandler(expr_ty type, identifier name, asdl_seq * body, int lineno, int
               col_offset, PyArena *arena)
 {
         excepthandler_ty p;
@@ -2928,7 +2928,7 @@ ast2obj_excepthandler(void* _o)
         if (PyObject_SetAttrString(result, "type", value) == -1)
                 goto failed;
         Py_DECREF(value);
-        value = ast2obj_expr(o->name);
+        value = ast2obj_identifier(o->name);
         if (!value) goto failed;
         if (PyObject_SetAttrString(result, "name", value) == -1)
                 goto failed;

Python/ast.c

@@ -2899,11 +2899,9 @@ ast_for_except_clause(struct compiling *c, const node *exc, node *body)
     else if (NCH(exc) == 4) {
         asdl_seq *suite_seq;
         expr_ty expression;
-        expr_ty e = ast_for_expr(c, CHILD(exc, 3));
+        identifier e = NEW_IDENTIFIER(CHILD(exc, 3));
         if (!e)
             return NULL;
-        if (!set_context(e, Store, CHILD(exc, 3)))
-            return NULL;
         expression = ast_for_expr(c, CHILD(exc, 1));
         if (!expression)
             return NULL;

Python/compile.c

@@ -1956,16 +1956,13 @@ compiler_try_except(struct compiler *c, stmt_ty s)
 		ADDOP(c, POP_TOP);
 		if (handler->name) {
             basicblock *cleanup_end, *cleanup_body;
-            expr_context_ty orig_ctx;
-            
-            assert(handler->name->kind == Name_kind);
 
             cleanup_end = compiler_new_block(c);
             cleanup_body = compiler_new_block(c);
             if(!(cleanup_end || cleanup_body))
                 return 0;
 
-			VISIT(c, expr, handler->name);
+            compiler_nameop(c, handler->name, Store);
             ADDOP(c, POP_TOP);
 
             /*
@@ -1998,14 +1995,10 @@ compiler_try_except(struct compiler *c, stmt_ty s)
 
             /* name = None */
             ADDOP_O(c, LOAD_CONST, Py_None, consts);
-            orig_ctx = handler->name->v.Name.ctx;
-            handler->name->v.Name.ctx = Store;
-            VISIT(c, expr, handler->name);
-
-            /* del name */            
-            handler->name->v.Name.ctx = Del;
-            VISIT(c, expr, handler->name);
-            handler->name->v.Name.ctx = orig_ctx;
+            compiler_nameop(c, handler->name, Store);
+
+            /* del name */
+            compiler_nameop(c, handler->name, Del);
 
 	        ADDOP(c, END_FINALLY);
 	        compiler_pop_fblock(c, FINALLY_END, cleanup_end);

Python/graminit.c

@@ -1053,7 +1053,7 @@ static arc arcs_46_2[2] = {
 	{0, 2},
 };
 static arc arcs_46_3[1] = {
-	{22, 4},
+	{19, 4},
 };
 static arc arcs_46_4[1] = {
 	{0, 4},

Python/symtable.c

@@ -1335,7 +1335,8 @@ symtable_visit_excepthandler(struct symtable *st, excepthandler_ty eh)
 	if (eh->type)
 		VISIT(st, expr, eh->type);
 	if (eh->name)
-		VISIT(st, expr, eh->name);
+        if (!symtable_add_def(st, eh->name, DEF_LOCAL))
+			return 0;
 	VISIT_SEQ(st, stmt, eh->body);
 	return 1;
 }