你的句子是说，程序员也许想在程序跑的时候纠正这个程序错误执行的代码。
再wiki百科上的 计算机专业的 意思是，运行中直接改变了。比如在：网页链接
Bounding Boxes: Some datasets provide bounding boxes and some provide masks only. To support training on multiple datasets we opted to ignore the bounding boxes that come with the dataset and generate them on the fly instead. We pick the smallest box that encapsulates all the pixels of the mask as the bounding box. This simplifies the implementation and also makes it easy to apply image augmentations that would otherwise be harder to apply to bounding boxes, such as image rotation.
这里的on the fly就是指我们不用原数据的bounding box，我们直接在代码跑的时候生成bounding box。
on the fly:
It can also be used in programming to describe changing a program while it is still running. 边跑边改代码也可以用
或者计算机边运行边插拔硬件 ，比如热插拔的usb，鼠标键盘