Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:
Hi Monks,
Why does a list assignment to a list in scalar context return the number of elements on the right side list, but NOT the last element of the left side list that has been assigned values?
I know that:
scalar((1,3,5)) #evaluates to the last element of the list --- 5 if( (5,3,0) ) #evaluates to the last element of the list --- 0, +thus evaluates to FALSE $val=(5,6,7); #evaluates to the last element of the list --- 7
and that:
$ret = (($i, $j, $k)=(5,6,8,9)); #evaluates to the number of el +ements on the right side list --- 4 if( ($k, $v) = ( 1, 0 ) ) #evaluates to the number of el +ements on the right side list --- 2, thus evaluates to TRUE while ( ($key, $value) = each %map ) #still evaluates to the number + of elements on the right side hash
Now check a scalar assignment to a scalar in scalar context: if( $i = 0 ) which will evaluate to the value of $i on the left side, thus evaluate to 0, thus evaluate to FALSE
but consider an example of list assignment above:
To me, it seems like it should evaluate to the value of list ($k, $v) on the left side just like $i above, thus should evaluate to the last element of list ($k, $v) --- $v, thus evaluate to 0 and at last should evaluate to --- FALSE, although I know the correct answer is it will evaluate to true.if( ($k, $v) = ( 1, 0 ) )
So, the question is: for what purpose are the designing principles of scalar assignment and list assignment both in scalar context completely different? Just for convenience of usage? Isn't that a bit confusing?
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Replies are listed 'Best First'. | |
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Re: list assignment to list in scalar context
by TGI (Parson) on Nov 09, 2012 at 03:33 UTC | |
Re: list assignment to list in scalar context (boolean)
by tye (Sage) on Nov 09, 2012 at 03:45 UTC | |
Re: list assignment to list in scalar context
by Anonymous Monk on Nov 09, 2012 at 15:45 UTC | |
by Anonymous Monk on Nov 15, 2012 at 08:50 UTC |