Though it is not the infallible oracle I once thought it was, I still make frequent use of
% perl -MO=Deparse,-p -e '<Perl code>'
...to figure out how perl is parsing something, or maybe to get a grip on some obfu. E.g. if you wonder what this one-liner does
-nle '}{print$.' foobar.txt
feed it to -MO=Deparse,-p (make sure to retain any other command line switches, like -nl here):
% perl -MO=Deparse,-p -nle '}{print$.'
BEGIN { $/ = "\n"; $\ = "\n"; }
LINE: while (defined(($_ = <ARGV>))) {
chomp($_);
}
{
print($.);
}
-e syntax OK
Note that the -p in this one-liner is part not perl's command line switch, but rather an argument to B::Deparse.
Less commonly , I use other backends, such as B::Terse and B::Concise, instead of B::Deparse. See also O and B.
the lowliest monk
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
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
You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
|
For: |
|
Use: |
| & | | & |
| < | | < |
| > | | > |
| [ | | [ |
| ] | | ] |
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
|
|