Re: One piece of code, two mysteries!

I get the same thing, but then, after checking perldoc threads |ack async -C12 I see

async BLOCK;
    "async" creates a thread to execute the block immediately followin
+g
    it. This block is treated as an anonymous subroutine, and so must
    have a semicolon after the closing brace. Like "threads->create()"
+,
    "async" returns a *threads* object.

$thr->error()
    Threads are executed in an "eval" context. This method will return
    "undef" if the thread terminates *normally*. Otherwise, it returns
    the value of $@ associated with the thread's execution status in i
+ts
    "eval" context.
[download]

eval? eval returns undef on failure, so I write

print timedCommand( 3, $cmd, $_ ) || "\$@ $@" for 2, 3, 4; ### LINE B 
+###
[download]

and I get

$ perl huh
1
 2

2
1
 2
 3

3
1
 2
 3
 4

4
[download]

Comment on Re: One piece of code, two mysteries! Select or Download Code

Replies are listed 'Best First'.
Re^2: One piece of code, two mysteries! by BrowserUk (Patriarch) on Oct 05, 2012 at 06:57 UTC
That's not too useful. By adding `\|\| "\$@ $@"`, you're putting the call to `timedCommand()` in a scalar context. Hence, the extra digit you are seeing output is from the `return @input` in a scalar context and thus is just a count of the number of undefs it contains. You aren't seeing anything at all from the `"\$@ $@"` bit -- note: no "$@" in the output. That might just as well be `timedCommand( ... ) \|\|''` for all the additional information it yields. The question remains, what happened to the contents of `@input`; and the answer appears to be: a bug caused it to disappear; which has been fixed if 5.16. Something I will have to wait until later to verify here. I'm actually most intrigued by the "modification of a readonly variable" message at this point. 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". In the absence of evidence, opinion is indistinguishable from prejudice. RIP Neil Armstrong	[reply] [d/l] [select]
Re^2: One piece of code, two mysteries! by Anonymous Monk on Oct 05, 2012 at 06:46 UTC
ok, second take, this returns something right `print "@input"; ### LINE A ### return my @foo = @input;` [download] `1 2 1 2 1 2 3 1 2 3 1 2 3 4 1 2 3 4` [download] i say its a bug in threads::shared, its undefing when it shouldn't `threads: 1.86 threads::shared: 1.4 C:\perl\5.14.1\bin\MSWin32-x86-multi-thread\perl.exe` [download]	[reply] [d/l] [select]
Re^2: One piece of code, two mysteries! by Anonymous Monk on Oct 05, 2012 at 06:37 UTC
bah, nevermind, ignore me	[reply]