Perl 內部結構詳解 -- PerlGuts Illustrated

之前想看一下Perl的實現，無意中搜到了這篇文章，對Perl內部類型的結構解釋的很清晰，推薦感興趣的都仔細看一下，想優化的時候做到心中有數。

接下來的幾篇blog將翻譯這篇文檔中常見類型的部分，做個記錄，加深印象，同時也方便大家閱讀理解。

PerlGuts Illustrated

直接命令行的方法查看：perl -MDevel::Peek -e "$a = 123; Dump $a"

簡單的例子用來查看變量內部結構：

use Devel::Peek;

$a  = 123;
@a = 1..10;
%a = 1..10;
		
Dump $a;
Dump \@a;
Dump \%a;

標量：

SV = IV(0x2410960) at 0x2410964
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 123

數組：

SV = RV(0x3a7190) at 0x3a7184
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x24109c4
  SV = PVAV(0x3a80ac) at 0x24109c4
    REFCNT = 2
    FLAGS = ()
    ARRAY = 0x24c1aec
    FILL = 9
    MAX = 9
    ARYLEN = 0x0
    FLAGS = (REAL)
    Elt No. 0
    SV = IV(0x24c0450) at 0x24c0454
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 1
    Elt No. 1
    SV = IV(0x24c0420) at 0x24c0424
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 2
    Elt No. 2
    SV = IV(0x24b7e40) at 0x24b7e44
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 3
    Elt No. 3
    SV = IV(0x24b7e50) at 0x24b7e54
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 4

Hash：

SV = RV(0xe7190) at 0xe7184
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x24aaa0c
  SV = PVHV(0x2401c94) at 0x24aaa0c
    REFCNT = 2
    FLAGS = (SHAREKEYS)
    ARRAY = 0x24bd47c  (0:3, 1:5)
    hash quality = 150.0%
    KEYS = 5
    FILL = 5
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "1" HASH = 0x806b80c9
    SV = IV(0x24b7ca0) at 0x24b7ca4
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 2
    Elt "3" HASH = 0xa400c7f3
    SV = IV(0x24b7c80) at 0x24b7c84
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 4
    Elt "7" HASH = 0xecc9d984
    SV = IV(0x24b7c60) at 0x24b7c64
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 8