Perl 变量 内部实现机制

核心模块 Devel::Peek  允许我们以C语言的角度来观察一个perl 标量。

数组的源代码定义为

struct xpvav {

char*  xav_array;  /* pointer to first array element */

SSize_t xav_fill;  /* Index of last element present */

SSize_t xav_max;    /* max index for which array has space */

IV      xof_off;    /* ptr is incremented by offset */

NV      xnv_nv;    /* numeric value, if any */

MAGIC*  xmg_magic;  /* magic for scalar array */

HV*    xmg_stash;  /* class package */

SV**    xav_alloc;  /* pointer to malloced string */

SV*    xav_arylen;

U8      xav_flags;

};

试着运行命令查看啊

C:\Users>perl  -MDevel::Peek -le "@a=(1,2,3); Dump(\@a)"

SV = IV(0x74bed0) at 0x74bed4

REFCNT = 1

FLAGS = (TEMP,ROK)

RV = 0x26cf97c

SV = PVAV(0x74cc38) at 0x26cf97c

REFCNT = 2

FLAGS = ()

ARRAY = 0x26bf5dc

FILL = 2

MAX = 3

ARYLEN = 0x0

FLAGS = (REAL)

Elt No. 0

SV = IV(0x74bda0) at 0x74bda4

REFCNT = 1

FLAGS = (IOK,pIOK)

IV = 1

Elt No. 1

SV = IV(0x74be70) at 0x74be74

REFCNT = 1

FLAGS = (IOK,pIOK)

IV = 2

Elt No. 2

SV = IV(0x74beb0) at 0x74beb4

REFCNT = 1

FLAGS = (IOK,pIOK)

IV = 3