Blocking readline() Call?

[Scott Brady Drummonds]

Hi, everyone,

I'm just figuring Python out but have become stalled with the following
snippit of code: For some reason, the program stalls after the "read line:
x" for the last line. The 'done reading cycle map' message is never
generated:

while 1:
line = file.readline()
if line == '':
continue
data = line.strip().sp lit(':')
cycleMap[int(data[0])] = int(data[1])
i = i + 1
print ('read line %d' % i)
file.close()
print ('done reading cycle map')

I thought readline() was supposed to be non-blocking. Have I misunderstood
something?

Thanks,
Scott


--
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[Peter Hansen]

Re: Blocking readline() Call?

Scott Brady Drummonds wrote:[color=blue]
>
> I'm just figuring Python out but have become stalled with the following
> snippit of code: For some reason, the program stalls after the "read line:
> x" for the last line. The 'done reading cycle map' message is never
> generated:
>
> while 1:
> line = file.readline()
> if line == '':
> continue[/color]

Correct this: you want "break", not continue.
[color=blue]
> data = line.strip().sp lit(':')
> cycleMap[int(data[0])] = int(data[1])
> i = i + 1
> print ('read line %d' % i)
> file.close()
> print ('done reading cycle map')
>
> I thought readline() was supposed to be non-blocking. Have I misunderstood
> something?[/color]

Yes, the problem wasn't where you thought it was. A well-placed print
statement or two would have showed you that readline was being called
repeatedly, not blocking.

-Peter

[Jp Calderone]

Re: Blocking readline() Call?

On Mon, Nov 10, 2003 at 11:59:42AM -0800, Scott Brady Drummonds wrote:[color=blue]
> Hi, everyone,
>
> I'm just figuring Python out but have become stalled with the following
> snippit of code: For some reason, the program stalls after the "read line:
> x" for the last line. The 'done reading cycle map' message is never
> generated:
>
> while 1:
> line = file.readline()
> if line == '':
> continue[/color]

I think you mean "break" here, not "continue".

[color=blue]
> data = line.strip().sp lit(':')
> cycleMap[int(data[0])] = int(data[1])
> i = i + 1
> print ('read line %d' % i)
> file.close()
> print ('done reading cycle map')[/color]


Another way to write this loop would be:

for line in file:
...

Jp

[Scott Brady Drummonds]

Re: Blocking readline() Call?


"Scott Brady Drummonds" <scott.b.drummo nds.nospam@inte l.com> wrote in
message news:booqnf$ioc $1@news01.intel .com...[color=blue]
> Hi, everyone,
>
> I'm just figuring Python out but have become stalled with the following
> snippit of code:[/color]
[code deleted]

JP said:[color=blue]
> I think you mean "break" here, not "continue".[/color]

Peter said:[color=blue]
> Correct this: you want "break", not continue[/color]

Mel said:[color=blue]
> 'continue' doesn't mean what you think it means. Try 'break'.[/color]

So, what is it that you people are trying to tell me? Please don't beat
around the bush.

Scott

P.S. Sarcasm aside, thanks to all three of you for pointing out my very
basic mistake. :)

[Paul Clinch]

Re: Blocking readline() Call?

"Scott Brady Drummonds" <scott.b.drummo nds.nospam@inte l.com> wrote in message news:<booqnf$io c$1@news01.inte l.com>...[color=blue]
> Hi, everyone,
>
> I'm just figuring Python out but have become stalled with the following
> snippit of code: For some reason, the program stalls after the "read line:
> x" for the last line. The 'done reading cycle map' message is never
> generated:
>
> while 1:
> line = file.readline()
> if line == '':
> continue[/color]

Perhaps you meant break.
[color=blue]
> data = line.strip().sp lit(':')
> cycleMap[int(data[0])] = int(data[1])
> i = i + 1
> print ('read line %d' % i)
> file.close()
> print ('done reading cycle map')
>
> I thought readline() was supposed to be non-blocking. Have I misunderstood
> something?
>
> Thanks,
> Scott[/color]

Regards, Paul Clinch

[Peter Hansen]

Re: Blocking readline() Call?

Scott Brady Drummonds wrote:[color=blue]
>
> "Scott Brady Drummonds" <scott.b.drummo nds.nospam@inte l.com> wrote in
> message news:booqnf$ioc $1@news01.intel .com...[color=green]
> > Hi, everyone,
> >
> > I'm just figuring Python out but have become stalled with the following
> > snippit of code:[/color]
> [code deleted]
>
> JP said:[color=green]
> > I think you mean "break" here, not "continue".[/color]
>
> Peter said:[color=green]
> > Correct this: you want "break", not continue[/color]
>
> Mel said:[color=green]
> > 'continue' doesn't mean what you think it means. Try 'break'.[/color]
>
> So, what is it that you people are trying to tell me? Please don't beat
> around the bush.[/color]

Sorry we were unclear, Scott. See Paul Clinch's post for an answer that
is more concise and perhaps easier for you to understand. ;-) ;-)

-Peter