用C语言模仿Python函数的一种简单实现方法

def line_conf(a, b):  def line(x):    return a*x + b  return lineline1 = line_conf(1, 1)line2 = line_conf(4, 5)print(line1(5), line2(5))

/* MIT LicenseCopyright (c) 2017 Yuandong-ChenPermission is hereby granted, free of charge, to any person obtaining a copyof this software and associated documentation files (the "Software"), to dealin the Software without restriction, including without limitation the rightsto use, copy, modify, merge, publish, distribute, sublicense, and/or sellcopies of the Software, and to permit persons to whom the Software isfurnished to do so, subject to the following conditions:The above copyright notice and this permission notice shall be included in allcopies or substantial portions of the Software.THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THEAUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHERLIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THESOFTWARE. *////////////////////////////////////////////////////////////////////////////////// Note: The C program is almost equivalent to the Python program as follows:// def line_conf(a, b)://   def line(x)://     return a*x + b//   return line//// line1 = line_conf(1, 1)// line2 = line_conf(4, 5)// print(line1(5), line2(5))#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <stdarg.h>typedef int Func();Func *line_conf(int x, int y,...){   va_list ap;   va_start(ap, y);  asm volatile(    "push %%eax/n/t"    "subl $40, %%esp/n/t"    "movl 8(%%ebp), %%eax/n/t"    "movl %%eax, -36(%%ebp)/n/t"    "movl 12(%%ebp), %%eax/n/t"    "movl %%eax, -40(%%ebp)/n/t"    "addl $40, %%esp/n/t"    "pop %%eax/n/t"    :::"memory"    );if(va_arg(ap,int) == 1){LINE:  asm volatile(    "push %%ebp/n/t"    "movl %%esp, %%ebp/n/t"    "movl 8(%%ebp), %%eax/n/t"    "imul -36(%%ebp), %%eax/n/t"    "addl -40(%%ebp), %%eax/n/t"    "movl %%ebp, %%esp/n/t"    "pop %%ebp/n/t"    "ret/n/t"    :::"memory","%eax"    );}  __END:   va_end(ap);  return (Func *)(&&LINE);}int main(int argc, const char *argv[]){   printf("====TEST START====/n");  printf("34*234+6 ?= %d/n",line_conf(34,6)(234));  printf("1*3+2 ?= %d; 324*65+3 ?= %d; 13*66+2 ?= %d/n",line_conf(1,2)(3),line_conf(324,3)(65),line_conf(13,2)(66));  int fd = line_conf(1,6)(4);  Func *fun = line_conf(3,3);  int a = 1; // Limited point  printf("3*3+3 ?= %d; 1*4+6 ?= %d/n",fun(3),fd);  printf("====TEST END====/n");  return 0; }// Compile it by the following command:// gcc -m32 -O0 -fno-stack-protector CFunctional.c; ./a.out// The terminal output should looks like:// ====TEST START====// 34*234+6 ?= 7962// 1*3+2 ?= 5; 324*65+3 ?= 21063; 13*66+2 ?= 860// 3*3+3 ?= 12; 1*4+6 ?= 10// ====TEST END====//Note: The limitation happens between line 86 and line 88, we cannot insert any function here// whose stack is larger than 40 bytes.(Why is 40? check the inline assembler language)