Re^2: Scalar Vs. List context

array and list elements: these are implicitly in list context.

Not true. Every expression can be evaluated in any context. The context in which the expression is evaluated is determined by the operator to which the expression is an operand.

Expressions that are list elements are no exception. The list operator decides the context of its operands based on its context:

@a = (1,2,3,4);  # list, list, list, list
$a = (1,2,3,4);  # void, void, void, scalar
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Expressions that are arrays are no exception.

@b = @a;   # @a is evaluated in list context.
$c = @a;   # @a is evaluated in scalar context.
@a; 1;     # @a is evaluated in void context.
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Re^3: Scalar Vs. List context by jwkrahn (Abbot) on Jul 12, 2009 at 12:52 UTC
Expressions that are list elements are no exception. The list operator decides the context of its operands based on its context: `@a = (1,2,3,4); # list, list, list, list` `$a = (1,2,3,4); # void, void, void, scalar` Your second example does not have any "list elements" because you can't have a list in scalar context.	[reply] [d/l] [select]
Re^4: Scalar Vs. List context by ikegami (Patriarch) on Jul 13, 2009 at 15:17 UTC
Not so. You're considering different definitions of "list" as equivalent. A list value can't be evaluated in scalar context. Or any context. They aren't operators, so they can't be evaluated. They exist on the stack. The list operator, on the other hand, can be evaluated in any context. Just like every other operator (as far as I know). `>perl -MO=Concise -e"@a = (1,2,3,4);" ... - <1> ex-list lKP ->8 <-- "l" for list context ...` [download] `>perl -MO=Concise -e"$a = (1,2,3,4);" ... 5 <@> list sKP ->6 <-- "s" for scalar context ...` [download] `>perl -MO=Concise -e"(1,2,3,4); 1" ... 4 <@> list vKP ->5 <-- "v" for void context ...` [download] A less ambiguous wording of the statement you made is: An operator can't evaluate to (return) a list in scalar context. A list operator can be evaluated in scalar context, but it must evaluate to a scalar in scalar context	[reply] [d/l] [select]
Re^4: Scalar Vs. List context by Anonymous Monk on Jul 12, 2009 at 12:55 UTC
Often repeated, but what do you call `( 1 , 2 , 3 , 4 );`? :D	[reply] [d/l]
Re^5: Scalar Vs. List context by jwkrahn (Abbot) on Jul 12, 2009 at 13:12 UTC
Comma Operator	[reply]
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Re^3: Scalar Vs. List context by ELISHEVA (Prior) on Jul 12, 2009 at 07:35 UTC
Hmmm. `use strict; use warnings; sub foo { print "wantarray? ", wantarray?1:0, "\n"; return wantarray? (1,2,3) : 's-s-sc-scalar'; } my @x =('a','b', foo(), 'c'); print "\@x=(@x)\n";` [download] prints `wantarray? 1 @x=(a b 1 2 3 c)` [download] Looks like list context to me. Best,beth	[reply] [d/l] [select]
Re^4: Scalar Vs. List context by ikegami (Patriarch) on Jul 12, 2009 at 12:07 UTC
You only showed that it can be evaluated in list context. Why did you ignore my snippet which showed how it can be called in scalar and void context? `sub foo { print "wantarray? ", wantarray?1:0, "\n"; } my @x =(foo(),foo(), foo()); my $x =(foo(),foo(), foo());` [download] `wantarray? 1 wantarray? 1 wantarray? 1 wantarray? 0 wantarray? 0 wantarray? 0` [download]	[reply] [d/l] [select]