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authorArmin Rigo <arigo@tunes.org>2004-10-28 16:32:00 (GMT)
committerArmin Rigo <arigo@tunes.org>2004-10-28 16:32:00 (GMT)
commit89a39461bff04b80bb4857790350e1ab30ff2df9 (patch)
tree54bc00a9ad30e8e49849874cfbca8543de62fa58 /Include/stringobject.h
parent063e1e846dc5c3fe593cef5b14cc429369dcd2c2 (diff)
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Wrote down the invariants of some common objects whose structure is
exposed in header files. Fixed a few comments in these headers. As we might have expected, writing down invariants systematically exposed a (minor) bug. In this case, function objects have a writeable func_code attribute, which could be set to code objects with the wrong number of free variables. Calling the resulting function segfaulted the interpreter. Added a corresponding test.
Diffstat (limited to 'Include/stringobject.h')
-rw-r--r--Include/stringobject.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/Include/stringobject.h b/Include/stringobject.h
index 3deea8f..0c7e5b6 100644
--- a/Include/stringobject.h
+++ b/Include/stringobject.h
@@ -37,6 +37,15 @@ typedef struct {
long ob_shash;
int ob_sstate;
char ob_sval[1];
+
+ /* Invariants:
+ * ob_sval contains space for 'ob_size+1' elements.
+ * ob_sval[ob_size] == 0.
+ * ob_shash is the hash of the string or -1 if not computed yet.
+ * ob_sstate != 0 iff the string object is in stringobject.c's
+ * 'interned' dictionary; in this case the two references
+ * from 'interned' to this object are *not counted* in ob_refcnt.
+ */
} PyStringObject;
#define SSTATE_NOT_INTERNED 0