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Re: $_ and list flattening with map()

by holo (Monk)
on Dec 14, 2003 at 21:44 UTC ( #314687=note: print w/replies, xml ) Need Help??

in reply to $_ and list flattening with map()

The line:

$_++ for map $_, @a;

generates an anonymous list with map, then iterates through it with for incrementing all its values. Once for is done, the list is thrown away (expensive no-op).

The line:

$_++ for my @b = map $_, @a;

generates a list with map and throws it in @b, then iterates through it with for incrementing all values as before. This time, the list is not anonymous and may be accessed by using @b and it's not thrown away. Once map is evaluated, values in @b are totaly independent from values in @a.

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[shmem]: well, previous to that << was always treated as the left-shift operator
[Eily]: or the here-doc operator
[Eily]: which is actually how it is parsed in this case
[shmem]: older versions of perl can't guess that "use of <<>> may be implemented someday" :D
Discipulus how much wise my brothers are? ;=)
[karlgoethebier]: thanks ;-
[karlgoethebier]: all for reading the manuals

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