Perl has some special constants that it returns as true and false in response to comparisons and some other boolean expressions. You can peek at the internals of these constants using Devel::Peek:
$ perl -MDevel::Peek -e'Dump(1 < 2)'
SV = PVNV(0xa1046e4) at 0xa102520
REFCNT = 2147483644
FLAGS = (PADTMP,IOK,NOK,POK,READONLY,pIOK,pNOK,pPOK)
IV = 1
NV = 1
PV = 0xa1055d0 "1"\0
CUR = 1
LEN = 12
$ perl -MDevel::Peek -e'Dump(1 > 2)'
SV = PVNV(0x947a6d0) at 0x9478510
REFCNT = 2147483647
FLAGS = (PADTMP,IOK,NOK,POK,READONLY,pIOK,pNOK,pPOK)
IV = 0
NV = 0
PV = 0x947a6c8 ""\0
CUR = 0
LEN = 12
Interesting observations:
Note the high REFCNT; this ensures that these constants are never destroyed by the garbage collector.
The PV shows you how these constants are stringified. True becomes "1" and false is the empty string.
The IV shows you how these constants are converted to integers. True becomes 1 and false is 0.
They're read-only...
$ perl -e'$x = \(1 < 2); $$x++'
Modification of a read-only value attempted at -e line 1.
I'm not going to say that these constants are never going to change (never say never!) but it would probably break a lot of code if they did, so I think p5p would be pretty wary of changing this. The Enterprise operator (see perlsecret) relies on them numifying as 0 and 1.
package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
-
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.