Do you understand context? It freaked me out once or fifty times too. =) When perl is compiling your code, it looks at structures like these and decides on what "context" codehere() is in: 
codehere(); #void context
$c=codehere();  #scalar context
($l)=codehere(); #list context
@a=codehere(); #list context
%h=codehere(); #list context
print codehere(); #list context
foreach (codehere()) { #list context
if ( 1 <= codehere() ) { #scalar context

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When you do something along the lines of this: $a=( codehere(),codehere() ); then the $a= forces the right side into scalar context since perl can see you don't want a list so in scalar context, the right side isn't treated as a list but as a statement group. Thus, "," is an operator that forces void context on it's left-hand-side and passes on the whatever context it is in to it's right-hand-side. Since you strung together a series of values like this: $a = ( 2, 3, 4, 5, 6 ); the first four numbers are in void context and only the last item in the series is in scalar context. Thus your statement could be rewritten: 2; 3; 4; 5; $a = 6;

And, bam!, from that you can see there are 4 constants in void context. Run either of those with perl -we on the command line and enjoy seeing the 4 warnings pop-up.

BTW, $a = ( 1, 5 ); pulls no error. =) It seems that perl and in fact Perl treat 1; special.

HTH Historical note, 4 years ago, or more, merlyn took me to task for snorting at the idea of a comma operator. =) I was so embarassed I re-read the pink camel from cover to cover before I ever posted to the c.l.p.m again. I wish I still had that archive, he explained in about 4 sentences what it took me 3 paragraphs to explain. oh well... =P

--
$you = new YOU;
honk() if $you->love(perl)

In reply to Re: Where is the constant? Where is the void context? by extremely
in thread useless use of a constant in a void context? by princepawn

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