【编程好习惯】引入中间变量使程序更易读

来源：未知责任编辑：责任编辑发表时间:2013-08-27 15:58　点击:次

今天查看自己为《专业嵌入式软件开发》一书所写的代码时发现，个别函数由于没有引入中间变量，使代码行既长又不易读。重构前后的代码如下所示。

重构前：

if (TIMER_STARTED == _handle->state_) { 
    timer_handle_t next; 
if (g_timer_next == _handle) { 
        g_timer_next = (timer_handle_t) dll_next (&g_bucket_firing->dll_,  
            &_handle->node_); 
    } 
    next = (timer_handle_t)dll_next  
        (&g_buckets [_handle->bucket_index_].dll_, &_handle->node_); 
if (0 != next) { 
        next->round_ += _handle->round_; 
    } 
    dll_remove (&g_buckets [_handle->bucket_index_].dll_, &_handle->node_); 
if (g_buckets [_handle->bucket_index_].reentrance_ > 0) { 
        g_bucket_firing->level_ ++; 
    } 
}

重构后：

if (TIMER_STARTED == _handle->state_) { 
    timer_handle_t next; 
bucket_t *p_bucket = &g_buckets [_handle->bucket_index_];
if (g_timer_next == _handle) { 
        g_timer_next = (timer_handle_t) dll_next (&g_bucket_firing->dll_,  
            &_handle->node_); 
    } 
    next = (timer_handle_t)dll_next (&p_bucket->dll_, &_handle->node_); 
if (0 != next) { 
        next->round_ += _handle->round_; 
    } 
    dll_remove (&p_bucket->dll_, &_handle->node_); 
if (p_bucket->reentrance_ > 0) { 
        g_bucket_firing->level_ ++; 
    } 
}