[Python-checkins] CVS: python/dist/src/Python symtable.c,2.9,2.10

[Jeremy Hylton]

Update of /cvsroot/python/python/dist/src/Python
In directory usw-pr-cvs1:/tmp/cvs-serv12577

Modified Files:
	symtable.c 
Log Message:
Add a comment explaining the st_symbols cache.


Index: symtable.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Python/symtable.c,v
retrieving revision 2.9
retrieving revision 2.10
diff -C2 -d -r2.9 -r2.10
*** symtable.c	2001/12/08 23:40:38	2.9
--- symtable.c	2001/12/10 00:53:18	2.10
***************
*** 5,8 ****
--- 5,22 ----
  #include "structmember.h"
  
+ /* The compiler uses this function to load a PySymtableEntry object
+    for a code block.  Each block is loaded twice, once during the
+    symbol table pass and once during the code gen pass.  Entries
+    created during the first pass are cached for the second pass, using
+    the st_symbols dictionary.  
+ 
+    The cache is keyed by st_nscopes.  Each code block node in a
+    module's parse tree can be assigned a unique id based on the order
+    in which the nodes are visited by the compiler.  This strategy
+    works so long as the symbol table and codegen passes visit the same
+    nodes in the same order.
+ */
+ 
+ 
  PyObject *
  PySymtableEntry_New(struct symtable *st, char *name, int type, int lineno)
***************
*** 15,19 ****
  		goto fail;
  	v = PyDict_GetItem(st->st_symbols, k);
! 	if (v) /* XXX could check that name, type, lineno match */ {
  		Py_DECREF(k);
  		Py_INCREF(v);
--- 29,33 ----
  		goto fail;
  	v = PyDict_GetItem(st->st_symbols, k);
! 	if (v) {
  		Py_DECREF(k);
  		Py_INCREF(v);