php - 如何编写我自己的克隆函数

Question

<分区>

Answer 1

第 1 部分

/* memcpy example */
#include <stdio.h>
#include <string.h>

struct {
  char name[40];
  int age;
} person, person_copy;

int main ()
{
  char myname[] = "Pierre de Fermat";

  /* using memcpy to copy string: */
  memcpy ( person.name, myname, strlen(myname)+1 );
  person.age = 46;

  /* using memcpy to copy structure: */
  memcpy ( &person_copy, &person, sizeof(person) );

  printf ("person_copy: %s, %d \n", person_copy.name, person_copy.age );

  return 0;
}

取自http://www.cplusplus.com/reference/clibrary/cstring/memcpy/

第 2 部分

我假设您需要复制复杂对象的所有子元素(如图 1 中复制假想对象 A，如果您只需要复制黑色对象但保持不变，则可以使用我上面链接的代码其他作为引用，下面的伪代码适用于你是否也想复制它的所有子项) 上图显示了现实如何以及我们如何看待一个对象

function MyCloneRecursive(object A) : object
{
    pointer Cpy;
    allocate memory to Cpy;
    memcpy(&Cpy,&A,sizeof(A))
    //now copy all its child elements
    //assuming there is a way to do a foreach that
    //for object A there are A.B,A.C and inside A.B there is D
    //and childname={"B","C"} and inside of B childname={"D"}
    for each childname in object A 
    {
        eval("Cpy." + childname + "=MyCloneRecursive(A." + childname + ")");
    }
}

//note this is really bad programming 
//clone function is better written in the runtime
//(or its a part of the intepreter not a includable code)