Interesting Thread Gotcha

[Dan]

On Jan 16, 1:33 pm, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
> Dan schrieb:
>
>
>
> > On Jan 16, 11:06 am, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
> >> Hendrik van Rooyen wrote:
> >>> "Dan" <the,,,ail.com> wrote:
> >>>>>>> keyboard_thread = thread.start_new_thread(kbd_driver (port_q,kbd_q))
> >>>> Needs to be
> >>>>>>> keyboard_thread = thread.start_new_thread(kbd_driver, (port_q,kbd_q))
> >>>> Commas are important!
> >>>> -Dan
> >>> Absolutely! - well spotted!
> >>> As the first correct respondent, you win the freedom to spend a week in
> >>> Naboomspruit at your own expense.
> >>> It would have been nice, however, to have gotten something like:
> >>> TypeError - This routine needs a tuple.
> >>> instead of the silent in line calling of the routine in question,
> >>> while failing actually to start a new thread.
> >> You can't prevent the silent inline-calling - otherwise, how would you do
> >> this:
>
> >> def compute_thread_target():
> >>     def target():
> >>         pass
> >>     return target
>
> >> thread.start_new_thread(compute_thread_target())
>
> >> Of course start_new_thread could throw an error if it got nothing callable
> >> as first argument. No idea why it doesn't.
>
> >> Diez
>
> > Of course, in his case, having start_new_thread throw an error
> > wouldn't have helped, since he went into an infinite loop while
> > evaluating the parameters for start_new_thread.
>
> > Would it be possible to have pychecker (or some such) warn that there
> > is an insufficient parameter count to start_new_thread? I guess that
> > would require knowing the type of thread. . .
>
> What has this to do with the second argument? It's perfectly legal to
> have a function as thread-target that takes no arguments at all, so
> enforcing a second argument wouldn't be helpful - all it would do is to
> force all developers that don't need an argument tuple to pass the empty
> tuple. So there was no insufficient argument count.
>
> And none of these would solve the underlying problem that in python
> expressions are evaluated eagerly. Changing that would mean that you end
> up with a totally new language.
>
> the only thing that could help to a certain extend would be static
> types. Which we don't want here :)
>
> Diez

It doesn't seem to be legal in my version of python (or the doc):

>>> import thread
>>> def bat():
	print "hello"


>>> thread.start_new_thread(bat)

Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    thread.start_new_thread(bat)
TypeError: start_new_thread expected at least 2 arguments, got 1
>>> thread.start_new_thread(bat, ())
2256hello


>>>

-Dan