The usual use is when the sort key must be derived from the data using a process that takes significant time/resources. The idea of the ST is to precalculate all of the sort keys before the sort operation so you only spend the time once:
@sorted =
map { $_->[ 1 ] }
sort { $a->[ 0 ] <=> $b->[ 0 ] }
map { [ expensivefunc( $_ ), $_ ] } @data;
Doing a naive sort, you would be calling that expensive function twice for every comparison, which would end up being a lot more than when precalculating:
@sorted = sort { expensivefunc( $a ) <=> expensivefunc( $b ) } @data;
-
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.
|