Re: wantarray alternative (Context propagation)

context is propagated into the return statement.

see Context propagation into subs and evals

and according to perldoc: map in scalar context, returns the total number of elements so generated.

But the following code forces the map-statement into a sliced list.

  DB<156> sub tst { (map {lc} @_)[0.. wantarray * $#_] }

  DB<157> @list=tst("A".."D")
 => ("a", "b", "c", "d")

  DB<158> $scalar=tst("A".."D")
 => "a"
[download]

and if the last value is enough for you in scalar context do

  DB<159> sub tst { (map {lc} @_)[0.. $#_] }

  DB<160> @list=tst("A".."D")
 => ("a", "b", "c", "d")

  DB<161> $scalar=tst("A".."D")
 => "d"
[download]

you haven't answered my question in Re^5: wantarray alternative yet, so you have both alternatives now.

Cheers Rolf

( addicted to the Perl Programming Language)

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Re^2: wantarray alternative by tqisjim (Beadle) on Jul 10, 2013 at 21:24 UTC
I don't seem to be answering as fast as you're asking. If the explanation is that map is being called in scalar context, then the following is unexpected: `sub lowercase { my @out = map { lc } @_ ; return @out ; } $name = lowercase( 'Jim', "Jeff" ) ; ## $name == 2` [download] Even though map is called in an array context, the results don't change. Very clever solution, yours. Clever, but not elegant.	[reply] [d/l]
Re^3: wantarray alternative by LanX (Saint) on Jul 10, 2013 at 21:29 UTC
> If the explanation is that map is being called in scalar context, then the following is unexpected: no! whatever comes after `return` is executed in the context of the sub's call. so in this caseš `$name = scalar @out` It's true many people expect a LIST to be returned but thats generally wrong in scalar context. A helper routine `sub listify { (@_)[0..$#_] }` might help to assure this "expected" behaviour, whenever you need to return a LIST˛. Cheers Rolf ( addicted to the Perl Programming Language) PS: please read the thread I linked before asking more questions. š) which isn't the code from the post I replied to, where a `map`-statement is returned UPDATE > Clever, but not elegant. Larry will be so devastated to hear this ... :´( UPDATE ˛) FWIW `DB<112> sub listify { (@_)[0..$#_] } DB<113> sub tst { listify map{lc} @_ } DB<114> $s =tst("A".."D") => "d" DB<115> @l =tst("A".."D") => ("a", "b", "c", "d")` [download]	[reply] [d/l] [select]
Re^4: wantarray alternative by tqisjim (Beadle) on Jul 10, 2013 at 22:28 UTC
Larry will be so devastated to hear this ... :´( Nuff said	[reply]

In Section Seekers of Perl Wisdom

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