eh? How does being force to use $_ add opportunities for optimization?
Theoretically the fact that there are several comparisons allows to make comparison to $_ with long strings faster (say more then 64 characters long). If the switch contains several "when" branches with string constants you can pre-compute hash of them and first compare a hash of $_ with hash of the constant and only if hash matches perform full comparison: you need to compute a single hash of $_ for all comparisons. If all "when" branches represent search without meta characters you can pre-compute a table via Knuth-Morris-Pratt for strings search.
-
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.
|