在初始化C中的多个资源的函数中处理错误(清理和中止)的一些好方

err=alloc_a()
if(err)
    clean_up_and_abort()

err=alloc_b()
if(err)
    clean_up_and_abort()

err=alloc_c()
if(err)
    clean_up_and_abort()

// ...

profit()

4：全局变量,哇哦！因为每个人都喜欢全局变量,就像他们喜欢goto一样.但严重的是,如果将变量的范围限制为文件范围(使用static关键字),那就不是那么糟糕了.附注：清理函数接收/返回错误代码不变,以便在init_function中整理代码.

static A *a = NULL;
static B *b = NULL;
static C *c = NULL;

uint32_t cleanup( uint32_t errcode )
{
    if ( c )
        dealloc_c(&c);
    if ( b )
        dealloc_b(&b);
    if ( a )
        dealloc_a(&a);

    return errcode;
}

uint32_t init_function( void )
{
    if ( alloc_a(&a) != SUCCESS )
        return cleanup(INIT_FAIL_A);

    if ( alloc_b(&b) != SUCCESS )
        return cleanup(INIT_FAIL_B);

    if ( alloc_c(&c) != SUCCESS )
        return cleanup(INIT_FAIL_C);

    profit(a,b,c);
    return INIT_SUCCESS;
}

5：人造OOP.对于那些无法处理真相的人(全局变量在C程序中实际有用),您可以采用C方法. C获取所有全局变量,将它们放入结构中,并将它们称为“成员”变量.不知怎的,这让每个人都开心.

诀窍是将指向结构的指针传递给所有函数,作为第一个参数. C在幕后执行此操作,在C中您必须明确地执行此操作.我调用指针,以避免与此冲突/混淆.

// define a class (uhm,struct) with status,a cleanup method,and other stuff as needed
typedef struct stResources
{
    char *status;
    A *a;
    B *b;
    C *c;
    void (*cleanup)(struct stResources *that);
}
stResources;

// the cleanup method frees all resources,and frees the struct
void cleanup( stResources *that )
{
    if ( that->c )
        dealloc_c( &that->c );
    if ( that->b )
        dealloc_b( &that->b );
    if ( that->a )
        dealloc_a( &that->a );

    free( that );
}

// the init function returns a pointer to the struct,or NULL if the calloc fails
// the status member variable indicates whether initialization succeeded,NULL is success
stResources *init_function( void )
{
    stResources *that = calloc( 1,sizeof(stResources) );

    if ( !that )
        return NULL;

    that->cleanup = cleanup;

    that->status = "Item A is out to lunch";
    if ( alloc_a( &that->a ) != SUCCESS )
        return that;

    that->status = "Item B is never available when you need it";
    if ( alloc_b( &that->b ) != SUCCESS )
        return that;

    that->status = "Item C is being hogged by some other process";
    if ( alloc_c( &that->c ) != SUCCESS )
        return that;

    that->status = NULL;  // NULL is success
    return that;
}

int main( void )
{
    // create the resources
    stResources *resources = init_function();

    // use the resources
    if ( !resources )
        printf( "Buy more memory alreadyn" );
    else if ( resources->status != NULL )
        printf( "Uhm yeah,so here's the deal: %sn",resources->status );
    else
        profit( resources->a,resources->b,resources->c );

    // free the resources
    if ( resources )
        resources->cleanup( resources );
}