Dag Sverre Seljebotn, 16.03.2011 13:37:
On 03/16/2011 12:54 PM, mark florisson wrote:
On 16 March 2011 11:58, Dag Sverre Seljebotn wrote:
I think we should make nested nogil-s noops, i.e.
with nogil:
with nogil: # => if True:
This is because one may want to change "with nogil" to "with gil" for
debugging purposes (allow printing debug information).
Interesting, that does sound convenient, but I'm not if mere
convenience should move us to simply ignore what is technically most
likely incorrect code (unless there is intermediate manual locking).
I'm just trying to minimize the "language getting in your way" factor. It
is pretty useless to write
if x:
if x:
...
as well, but Python does allow it.
That's because it's not necessarily useless. It can have side-effects.
In any case, I wouldn't really be against that. If you simply want to
allow this for debugging, we could also allow print statements in
nogil sections, by either rewriting it using 'with gil:', or by
inserting a simple printf (in which case you probably want to place a
few restrictions).
It's not only print statements. I.e., if I think something is wrong with an
array, I'll stick in code like
print np.std(x), np.mean(x), np.any(np.isnan(x))
or something more complex that may require temporaries. Or even plot the
vector:
plt.plot(x)
plt.show() # blocks until I close plot window
Or, launch a debugger:
if np.any(np.isnan(x)):
import pdb; pdb.set_trace()
All of these are better expressed using an explicit "with gil", also in
debug code.
Stefan
_______________________________________________
cython-devel mailing list
cython-devel@python.org
http://mail.python.org/mailman/listinfo/cython-devel
