From: Neil Schemenauer <nascheme@enme.ucalgary.ca>
Date: Thu, 11 Mar 2004 01:00:44 +0000 (+0000)
Subject: Document one of the many problems with the buffer object.
X-Git-Tag: v2.4a1~722
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0eadcd9cbbc3e165f046fa01025e2a76084a8e52;p=thirdparty%2FPython%2Fcpython.git

Document one of the many problems with the buffer object.
---

diff --git a/Objects/bufferobject.c b/Objects/bufferobject.c
index fe2be735bb3c..561d6c160d97 100644
--- a/Objects/bufferobject.c
+++ b/Objects/bufferobject.c
@@ -228,10 +228,17 @@ buffer_hash(PyBufferObject *self)
 	if ( self->b_hash != -1 )
 		return self->b_hash;
 
+	/* XXX potential bugs here, a readonly buffer does not imply that the
+	 * underlying memory is immutable.  b_readonly is a necessary but not
+	 * sufficient condition for a buffer to be hashable.  Perhaps it would
+	 * be better to only allow hashing if the underlying object is known to
+	 * be immutable (e.g. PyString_Check() is true).  Another idea would
+	 * be to call tp_hash on the underlying object and see if it raises
+	 * an error. */
 	if ( !self->b_readonly )
 	{
-		/* ### use different wording, since this is conditional? */
-		PyErr_SetString(PyExc_TypeError, "unhashable type");
+		PyErr_SetString(PyExc_TypeError,
+				"writable buffers are not hashable");
 		return -1;
 	}