Re^5: Easiest way to do something only on first iteration of loop

Athanasius Thank you for the correction!

I played with your code and even if the for loops are in a subroutine, the state version of $x is never re-initialized. In the documentation, my brain got stuck when the first sentence compared it to a my variable, causing a brain cramping mis-reading of the rest! Great that we have more eyeballs than mine on this stuff!

One thing I didn't test was behavior in threads. I am not sure what would happen.

Comment on Re^5: Easiest way to do something only on first iteration of loop

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Re^6: Easiest way to do something only on first iteration of loop by BrowserUk (Patriarch) on May 08, 2016 at 12:48 UTC
One thing I didn't test was behavior in threads. I am not sure what would happen. As with all variables that are not explicitly shared, each thread gets its own copy of any state variable; but within that thread it performs consistently with its behaviour in 'non-threaded' (single-threaded) code as you would expect: `CC:\test>perl -Mthreads -E" async{ for(1..4){ state $x = 123; say thre +ads->tid, ':', $x++ } }->join for 1 .. 4" 1:123 1:124 1:125 1:126 2:123 2:124 2:125 2:126 3:123 3:124 3:125 3:126 4:123 4:124 4:125 4:126` [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". I knew I was on the right track :) In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l]

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Re^6: Easiest way to do something only on first iteration of loop
by BrowserUk (Patriarch) on May 08, 2016 at 12:48 UTC

One thing I didn't test was behavior in threads. I am not sure what would happen.

As with all variables that are not explicitly shared, each thread gets its own copy of any state variable; but within that thread it performs consistently with its behaviour in 'non-threaded' (single-threaded) code as you would expect:

CC:\test>perl -Mthreads -E" async{ for(1..4){ state $x = 123; say thre
+ads->tid, ':', $x++ } }->join for 1 .. 4"
1:123
1:124
1:125
1:126
2:123
2:124
2:125
2:126
3:123
3:124
3:125
3:126
4:123
4:124
4:125
4:126
[download]

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". I knew I was on the right track :)

In the absence of evidence, opinion is indistinguishable from prejudice.

[reply]
[d/l]