Beefy Boxes and Bandwidth Generously Provided by pair Networks
Your skill will accomplish
what the force of many cannot
 
PerlMonks  

Comment on

( #3333=superdoc: print w/ replies, xml ) Need Help??

The problem with your original version is that the use constant executes at compile time, but the regular expression executes at run time - i.e. after everything has been compiled - so it's setting the $CONF_PATH variable too late. To see the difference between compile time and run time, run this:

print "World\n"; BEGIN { print "Hello " };

And the use keyword (plus its friend no) runs conceptually in a BEGIN block.

A do { ... } block provides a neat solution:

package mylib; use constant { MODULE_PATH => __FILE__, CONF_PATH => do { $_ = __FILE__; s/pm$/conf/i; $_ }, }; print CONF_PATH;

If your perl is fairly recent, you can do away with do and use /r.

package mylib; use constant { MODULE_PATH => __FILE__, CONF_PATH => (__FILE__ =~ s/pm$/conf/ir), }; print CONF_PATH;
perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

In reply to Re: BEGIN block and failure to initialize constants by tobyink
in thread BEGIN block and failure to initialize constants by temporal

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



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • Outside of code tags, you may need to use entities for some characters:
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

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

    How do I use this? | Other CB clients
    Other Users?
    Others lurking in the Monastery: (10)
    As of 2014-08-21 18:29 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      The best computer themed movie is:











      Results (141 votes), past polls