Enhance issubclass() and PyObject_IsSubclass() so that a tuple is

supported as the second argument. This has the same meaning as
for isinstance(), i.e. issubclass(X, (A, B)) is equivalent
to issubclass(X, A) or issubclass(X, B). Compared to isinstance(),
this patch does not search the tuple recursively for classes, i.e.
any entry in the tuple that is not a class, will result in a
TypeError.

This closes SF patch #649608.

1 files changed, 8 insertions, 3 deletions

diff --git a/Doc/api/abstract.tex b/Doc/api/abstract.tex
index 1cf69dc..91c0944 100644
--- a/Doc/api/abstract.tex
+++ b/Doc/api/abstract.tex
@@ -205,10 +205,15 @@ determination.
                                             PyObject *cls}
   Returns \code{1} if the class \var{derived} is identical to or
   derived from the class \var{cls}, otherwise returns \code{0}.  In
-  case of an error, returns \code{-1}.  If either \var{derived} or
-  \var{cls} is not an actual class object, this function uses the
-  generic algorithm described above.
+  case of an error, returns \code{-1}. If \var{cls}
+  is a tuple, the check will be done against every entry in \var{cls}.
+  The result will be \code{1} when at least one of the checks returns
+  \code{1}, otherwise it will be \code{0}. If either \var{derived} or
+  \var{cls} is not an actual class object (or tuple), this function
+  uses the generic algorithm described above.
   \versionadded{2.1}
+  \versionchanged[Older versions of Python did not support a tuple
+                  as the second argument]{2.3}
 \end{cfuncdesc}