我可以撤消或删除 atexit 命令吗？
如果我将 atexit( fn ); 放在退出堆栈上，它将在程序退出时执行：从 main() 返回或通过 exit()< /代码>。
我可以将其从堆栈中删除吗？
你问我为什么要这样做？
我正在使用 atexit、setjmp 和 longjmp 尝试一种简单的 try-catch 机制。如果我可以 undo-atexit(fn); - 即使它只适用于最后注册的函数，那就完美了。
编辑：
按照 monoceres 的建议制作我自己的堆栈...
该堆栈目前仅适用于一个异常捕获器。
void (*_catchFn[10])() = {0,0,0,0,0,0,0,0,0,0};
void _catch(){
if ( _catchFn[0] != 0 ){
(_catchFn[0])();
}
}
void _addCatch( void (*fn)() ){
_catchFn[0]=fn;
}
void _remCatch( void (*fn)() ){
_catchFn[0]=0;
}
void test(){
jmp_buf env;
void catch(){ // we get here after an exit with a registered catch
longjmp(env,1); // return to the line marked except...
// that first will get the value 1
}
int first = setjmp( env); // ** return here **
fprintf( stderr , "test: After setjmp. first=%d\n" , first );
if( first == 0 ){ // try this code
_addCatch(catch); // register the catch function to 'catch' the exit
fprintf( stderr , "test: Before CHECK\n" );
// CHECK something and something bad happens and it exits
exit(1); // like this
fprintf( stderr , "test: After CHECK - THIS SHOULD NEVER BE SEEN AFTER AN EXCEPTION.\n" );
}else{
fprintf( stderr , "test: After longjmp return. first=%d\n" , first );
}
_remCatch( catch);
fprintf( stderr , "test: IT WORKED!\n");
exit(1); // exit again to see if we are safe
}
int main(){
atexit( _catch ); // register my global exception stack
test();
}
If I place atexit( fn ); on the exit stack, it will get executed when the program exits: returns from main() or via exit().
Can I remove it from the stack?
Why do I want to do this, you ask?
I was experimenting with a simple try-catch mechanism using atexit, setjmp and longjmp. It would be just perfect if I could undo-atexit(fn); - even if it would only work for the last registered function.
Edit:
Following monoceres' suggestion to make my own stack...
The stack only works with one exception catcher for now.
void (*_catchFn[10])() = {0,0,0,0,0,0,0,0,0,0};
void _catch(){
if ( _catchFn[0] != 0 ){
(_catchFn[0])();
}
}
void _addCatch( void (*fn)() ){
_catchFn[0]=fn;
}
void _remCatch( void (*fn)() ){
_catchFn[0]=0;
}
void test(){
jmp_buf env;
void catch(){ // we get here after an exit with a registered catch
longjmp(env,1); // return to the line marked except...
// that first will get the value 1
}
int first = setjmp( env); // ** return here **
fprintf( stderr , "test: After setjmp. first=%d\n" , first );
if( first == 0 ){ // try this code
_addCatch(catch); // register the catch function to 'catch' the exit
fprintf( stderr , "test: Before CHECK\n" );
// CHECK something and something bad happens and it exits
exit(1); // like this
fprintf( stderr , "test: After CHECK - THIS SHOULD NEVER BE SEEN AFTER AN EXCEPTION.\n" );
}else{
fprintf( stderr , "test: After longjmp return. first=%d\n" , first );
}
_remCatch( catch);
fprintf( stderr , "test: IT WORKED!\n");
exit(1); // exit again to see if we are safe
}
int main(){
atexit( _catch ); // register my global exception stack
test();
}
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评论（3）
为什么不构建您自己的堆栈并从单个 atexit() 函数调用？这样你就可以随心所欲地操纵堆栈。
Why not build your own stack that you call from a single atexit() function? That way you could manipulate the stack all you want.
不，您不能这样做，但您可以使用全局标志，因此如果设置了该标志，您的退出处理程序将不执行任何操作。
或者，您可以调用
_Exit()(C99) - 它将执行正常的退出过程（关闭所有打开的描述符，发送所有需要的信号和父/子），但不会调用退出处理程序。No, you cannot do it, but you can use global flag so your exit handler will be doing nothing if the flag is set.
Alternatively you can call
_Exit()(C99) - it will perform normal exit procedure (close all open descriptors, send all needed signals and parent/children) but will not call exit handler.模块的 C 实现中有一个未记录的
atexit._clear函数，可以执行此操作https://github.com/python/cpython/blob/29c04dfa2718dd25ad8b381a1027045b312f9739/Modules/atexitmodule.c#L301
there is an undocumented
atexit._clearfunc in the C implementation of the module that does thishttps://github.com/python/cpython/blob/29c04dfa2718dd25ad8b381a1027045b312f9739/Modules/atexitmodule.c#L301