[Cython] operator() bug in cython

[Ulrich Dobramysl]

On Fri Feb 13 2015 at 2:23:45 PM Stefan Behnel <stefan_ml at behnel.de> wrote:

> Ulrich Dobramysl schrieb am 11.02.2015 um 09:56:
> > From what I've been able to work out, the problem seems to be that the
> call
> > to "t()" is treated as a NameNode in ExprNodes.py and not an
> AttributeNode.
> > However, I don't know enough about Cython's internals to track where
> > exactly this decision is made.
> >
> > Curiously, this bug isn't always triggered in more complex situations. I
> > had a larger pxd file with multiple external declarations where one class
> > operator() was treated correctly, while others weren't. I haven't been
> able
> > to find out why this was the case.
>
> It happens only with stack allocated C++ objects, not with heap objects
> (i.e. pointers). That can be used as a work-around, I guess.
>
>
Thanks! I haven't figured out how to call heap allocated objects, as the
code
---
cdef OperatorTest *t = new OperatorTest()
t()
---
is not translatable by Cython. Is there a special syntax for calling cython
"function pointers"? The trick dereference(t)() doesn't work either.

However, one thing that works is if the (stack-allocated) called object is
not a local variable (a NameNode), but an attribute of some object (an
AttributeNode). A quick and dirty fix for this would be this patch for
NameNode.calculate_result_code:
---
diff --git a/Cython/Compiler/ExprNodes.py b/Cython/Compiler/ExprNodes.py
index f99ec6e..f894a64 100644
--- a/Cython/Compiler/ExprNodes.py
+++ b/Cython/Compiler/ExprNodes.py
@@ -1904,6 +1904,8 @@ class NameNode(AtomicExprNode):
         entry = self.entry
         if not entry:
             return "<error>" # There was an error earlier
+        if entry.cname=='operator()':
+            return self.name
         return entry.cname

     def generate_result_code(self, code):
---
But I have no idea what other side effects that might have.

Ulrich
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