Joel wrote:
>
Can you tell me the sequence of events that happen (internally in perl
during parsing) for the following code:
sub fun
{
print @_;
}
fun fun (1), fun 2, fun (3);
I am particularly interested in the comma operator, in the above code,
as I understand it
(1) first the list operations (which have highest precedence because
of parantheses) will execute first printing "13".
(2) then the comma between fun(1) and fun 2 is evaluated, once this
happens, is the list operation ( fun 2, fun(3) ) evaluated or is the
comma between 2 and fun(3) evaluated?
I suspect you are forgetting that fun() itself returns the success
status of the print() function, introducing additional 1s into the
output. Look:
local $" = ',';
sub fun {
print "fun(@_) ";
}
fun fun ('a'), fun 'b', fun ('c');
**OUTPUT**
fun(a) fun(c) fun(b,1) fun(1,1)
The line
fun fun ('a'), fun 'b', fun ('c');
parses as
fun(fun('a'), fun('b', fun('c')));
and each parameter list is evaluated from left to right, hence the order
shown by the code's output.
HTH,
Rob
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