threads and return values

[Timothy Smith]

say i'm issuing

t = Thread(target=l ambda: WeeklyReportPDF .MakeReport(sel f.UserNameValue ,
self.PassWordVa lue,ReportType, self.db))
t.start()

which works just fine, BUT how do i get access to the return value of
WeeklyReportPDF .MakeReport() ??

[Paul Rubin]

Re: threads and return values

Timothy Smith <timothy@open-networks.netwri tes:

t = Thread(target=l ambda:
WeeklyReportPDF .MakeReport(sel f.UserNameValue ,
self.PassWordVa lue,ReportType, self.db))
t.start()
>
which works just fine, BUT how do i get access to the return value of
WeeklyReportPDF .MakeReport() ??

You can't. Make the function send you a message through some
synchronized communication mechanism. The Pythonic favorite way to do
that is with Queue, even when it's just one value (untested):

import Queue
q = Queue()
t = Thread(target = lambda q=q: q.put(WeeklyRep ortPDF.MakeRepo rt(...)))
t.start()
...

Now if you say

value = q.get()

the caller will block until WeeklyReportPDF .MakeReport returns. If
you say

value = q.get(False)

the False argument says not to block, so if WeeklyReportPDF .MakeReport
hasn't yet returned, q.get will raise the Queue.Empty exception, which
you can then catch and deal with. Another arg lets you specify a
timeout:

value = q.get(False, 3.0)

blocks for up to 3 seconds, then raises Queue.Empty.

[Paul Rubin]

Re: threads and return values

Paul Rubin <http://phr.cx@NOSPAM.i nvalidwrites:

import Queue
q = Queue()

Oops, meant

q = Queue.Queue()