perl - 什么决定了 Devel::Peek 的 LEN 值

Question

为什么LEN从过去的Dump80 年来到这里？

#!/usr/bin/env perl
use warnings;
use strict;
use 5.10.1;
use Devel::Peek;

my $a = 'a';
Dump $a;

print 'Enter an "a": ';
$a = <>;
chomp $a;
Dump $a;

my $b = 'a';
Dump $b;

print 'Enter an "a": ';
my $c = <>;
chomp $c;
Dump $c;

输出：

SV = PV(0x125b090) at 0x127e018
REFCNT = 1
FLAGS = (PADMY,POK,pPOK)
PV = 0x126df80 "a"\0
CUR = 1
LEN = 16
Enter an "a": a
SV = PV(0x125b090) at 0x127e018
REFCNT = 1
FLAGS = (PADMY,POK,pPOK)
PV = 0x126df80 "a"\0
CUR = 1
LEN = 16
SV = PV(0x125b190) at 0x127e0d8
REFCNT = 1
FLAGS = (PADMY,POK,pPOK)
PV = 0x1290da0 "a"\0
CUR = 1
LEN = 16
Enter an "a": a
SV = PV(0x125b1a0) at 0x128f260
REFCNT = 1
FLAGS = (PADMY,POK,pPOK)
PV = 0x1285c70 "a"\0
CUR = 1
LEN = 80

Answer 1

因为在您的定义中$c，您从 STDIN 设置了它，解释器可能为该操作预先分配了一些空间，以减少以后必须分配更多空间的可能性。

一般来说，Perl 像喝醉的水手一样消耗内存，而不是潜在地损害性能。一旦分配了一些内存，除非您的操作系统内存不足，否则它永远不会被释放。