perlquestion
Anonymous Monk
<p>
Hi Monks,
</p>
<p>
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?
</p>
<p>
I know that:
</p>
<code>
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
</code>
<p>
and that:
</p>
<code>
$ret = (($i, $j, $k)=(5,6,8,9)); #evaluates to the number of elements on the right side list --- 4
if( ($k, $v) = ( 1, 0 ) ) #evaluates to the number of elements on the right side list --- 2, thus evaluates to TRUE
while ( ($key, $value) = each %map ) #still evaluates to the number of elements on the right side hash
</code>
<p>
Now check a scalar assignment to a scalar in scalar context:
if( $i = 0 )
which will evaluate to the value of $i on the left side, thus evaluate to 0, thus evaluate to FALSE
</p>
<p>
but consider an example of list assignment above:
<code>
if( ($k, $v) = ( 1, 0 ) )
</code>
To me, it seems like it should evaluate to the value of list ($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.
</p>
<p>
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?
</p>
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