2009/3/21 Lisandro Dalcin <[email protected]>
> On Sat, Mar 21, 2009 at 9:24 AM, Stefan Behnel <[email protected]>
> wrote:
> >>>>>
> >>>>> for i from 0 <= i < 10:
> >>>>> print i
> >>>>> i += 5
> >
> > So I'm +1 for officially allowing the above and making it exit early.
> > Letting Cython basically ignore the "i += 5" would be a bug.
> >
>
> Me too, +1.
>
>
>
> --
> Lisandro Dalcín
> ---------------
> Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
> Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
> Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
> PTLC - Güemes 3450, (3000) Santa Fe, Argentina
> Tel/Fax: +54-(0)342-451.1594
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>
I looked at a range optimization example
cdef int g():
print "g called"
return 10
def f():
cdef int i
for i in range(0, g(), 2):
print i
i += 2
This gives the following output -
>>>
g called
0
4
8
Is this the output we are expecting? I for one expected i to hold the next
value from the list supplied by range every time it iterates over the loop,
inspite of i being defined as a cdef int type.
I created a temp variable inside Nodes.py. Every time i enter the loop, i
assign the loop counter var to the temp. Inside the loop, there on I can
modify the loop counter, but at the end of the loop i reassign the temp back
to the loop counter var.
This is the code change i made
diff -r 651a88137be7 Cython/Compiler/Nodes.py
--- a/Cython/Compiler/Nodes.py Fri Mar 20 17:51:46 2009 +0100
+++ b/Cython/Compiler/Nodes.py Sun Mar 22 21:05:41 2009 +0530
@@ -3968,6 +3968,7 @@
loopvar_name = self.loopvar_node.result()
if from_range:
range_bound = code.funcstate.allocate_temp(self.bound2.type,
manage_ref=False)
+ temp_loop_counter =
code.funcstate.allocate_temp(self.loopvar_node.type, manage_ref=False)
code.putln("%s = %s;" % (range_bound, self.bound2.result()))
# Skip the loop entirely (and avoid assigning to the loopvar)
if
# the loop is empty:
@@ -3976,18 +3977,22 @@
))
else:
range_bound = self.bound2.result()
code.putln(
"for (%s = %s%s; %s %s %s; %s%s) {" % (
loopvar_name,
self.bound1.result(), offset,
loopvar_name, self.relation2, range_bound,
loopvar_name, incop))
+ if from_range:
+ code.putln("%s = %s;" % (temp_loop_counter, loopvar_name))
if self.py_loopvar_node:
self.py_loopvar_node.generate_evaluation_code(code)
self.target.generate_assignment_code(self.py_loopvar_node,
code)
self.body.generate_execution_code(code)
code.put_label(code.continue_label)
if from_range:
+ code.putln("%s = %s;" % (loopvar_name, temp_loop_counter))
# Undo last increment to maintain Python semantics:
code.putln("} %s%s;" % (loopvar_name, decop))
# End the outer if statement:
With that I get the following output-
g called
0
2
4
6
8
Shouldn't this be the expected output?
--
Regards,
Anoop S.
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