Collection modifying problem

[nondos]

Hello



I have a thread that run loop in queue variable like this:



For each <somethingas <somethingin <queue variable>

Next



And the thread and the loop work fine



I have problem when i want to add something to the queue and the thread is
running i get error message "Collection was modified; enumeration operation
may not execute." Is there any way to solve this? I thought about this:

For I=1 to queue.count

Next

And when the loop end check if there's new items on queue



But I prefer if there is another solution with first loop



Thanks



P.S sorry for my English

[Armin Zingler]

Re: Collection modifying problem

"nondos" <nondos@hotmail .comschrieb

Hello
>
>
>
I have a thread that run loop in queue variable like this:
>
>
>
For each <somethingas <somethingin <queue variable>
>
Next
>
>
>
And the thread and the loop work fine
>
>
>
I have problem when i want to add something to the queue and the
thread is running i get error message "Collection was modified;
enumeration operation may not execute." Is there any way to solve
this? I thought about this:
>
For I=1 to queue.count
>
Next
>
And when the loop end check if there's new items on queue
>
>
>
But I prefer if there is another solution with first loop

No. Not when using For-Each.

Even using the second loop isn't the best solution, because the loop's end
value is evaluated when starting the loop, not each time. So, If queue.count
is modified during the loop, the initial value of queue.count is the number
of iterations performed.

A Do-Loop would fit better:

Do until i>queue.count
if bla then
...
i +=1
else
remove item from queue
'no i += 1 here
end if
Loop



Armin

[nondos]

Re: Collection modifying problem

thanks

[=?windows-1252?Q?G=F6ran_Andersson?=]

Re: Collection modifying problem

Armin Zingler wrote:

Even using the second loop isn't the best solution, because the loop's end
value is evaluated when starting the loop, not each time. So, If
queue.count
is modified during the loop, the initial value of queue.count is the number
of iterations performed.
>
A Do-Loop would fit better:
>
Do until i>queue.count
if bla then
...
i +=1
else
remove item from queue
'no i += 1 here
end if
Loop
>
>
>
Armin
>

That's not a good solution either. Adding items to a queue is not a
thread safe operation, so what the OP really needs is some proper thread
safety, not another way of looping the items.

--
Göran Andersson
_____

http://www.guffa.com

[Armin Zingler]

Re: Collection modifying problem

"Göran Andersson" <guffa@guffa.co mschrieb

Armin Zingler wrote:

Even using the second loop isn't the best solution, because the
loop's end value is evaluated when starting the loop, not each
time. So, If queue.count
is modified during the loop, the initial value of queue.count is
the number of iterations performed.

A Do-Loop would fit better:

Do until i>queue.count
if bla then
...
i +=1
else
remove item from queue
'no i += 1 here
end if
Loop



Armin

>
That's not a good solution either. Adding items to a queue is not a
thread safe operation, so what the OP really needs is some proper
thread safety, not another way of looping the items.

What else he does is not my problem. His problem was that modifying an
object that is used with For-Each, does not work. I have shown a general
solution to iterate through a list while it is being modified. The error he
gets is not a threading problem in first place.


Armin