Given:
sub foo {
my (undef, $x) = @_;
print $_[0], $x;
}
my $big = 'a' x 99999999;
foo($big, 'bar');
Does the list assignment of $_[0] to undef incur any significant runtime cost?
I expect that it doesn't, and would like to know what goes on under the hood.
I can't tell what happens in an aassign:
$ perl -MO=Concise -e '(undef) = $x'
8 <@> leave[1 ref] vKP/REFC ->(end)
1 <0> enter ->2
2 <;> nextstate(main 1 -e:1) v:{ ->3
7 <2> aassign[t1] vKS ->8
- <1> ex-list lK ->5
3 <0> pushmark s ->4
- <1> ex-rv2sv sK/1 ->-
4 <$> gvsv(*x) s ->5
- <1> ex-list lK ->7
5 <0> pushmark s ->6
6 <0> undef sP ->7
-e syntax OK
$ perl -MO=Concise -e '($y) = $x'
8 <@> leave[1 ref] vKP/REFC ->(end)
1 <0> enter ->2
2 <;> nextstate(main 1 -e:1) v:{ ->3
7 <2> aassign[t1] vKS ->8
- <1> ex-list lK ->5
3 <0> pushmark s ->4
- <1> ex-rv2sv sK/1 ->-
4 <$> gvsv(*x) s ->5
- <1> ex-list lK ->7
5 <0> pushmark s ->6
- <1> ex-rv2sv sKPRM*/1 ->-
6 <$> gvsv(*y) s ->7
-e syntax OK
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|