Beefy Boxes and Bandwidth Generously Provided by pair Networks
Come for the quick hacks, stay for the epiphanies.
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??

Hello fionbarr,

When I use 'given/when' I get the message 'given is experimental' and the program will not compile.

Are you using a very old version of Perl? According to perlexperiment, the smartmatch feature was introduced in Perl 5.10.0, so unless your version is older than that, the program should compile OK — but emit warnings — as long as you remember to use feature 'switch':

0:33 >perl -we "use feature 'switch'; my $c = 42; given ($c) { when ( +$_ < 50) { print 'Yes!' } }" given is experimental at -e line 1. when is experimental at -e line 1. Yes! 0:33 >

The warnings can be turned off with this pragma:

no warnings 'experimental::smartmatch';

But if you’re going to use when, you should still replace the topicaliser given with its more prosaic alternative for, as explained by brian_d_foy in his article “Use for() instead of given().”

However, even the use of when is not recommended for production code. For other switch options, begin with How-do-I-create-a-switch-or-case-statement of perlfaq7. And if a dispatch table doesn’t meet your particular needs, what’s wrong with if/elsif/.../else, anyway? :-)

Hope that helps,

Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,


In reply to Re: switch statement by Athanasius
in thread switch statement by fionbarr

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • 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.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others musing on the Monastery: (4)
As of 2024-03-28 23:26 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found