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由 Dmitriy Kiriyenko 提交于
When you add one callack in two separate `set_callback` calls - it is only called once. When you do it in one `set_callback` call - it is called twice. This violates the principle of least astonishment for me. Duplicating callback is usually an error. There is a correct and obvious way to do anything without this "feature". If you want to do before_save :clear_balance, :calculate_tax, :clear_balance or whatever, you should better do before_save :carefully_calculate_tax def carefully_calculate_tax clear_balance calculate_tax clear_balance end And this even opens gates for some advanced refactorings, unlike the first approach. My assumptions are: - Principle of least astonishment is violated, when callbacks are either prevented from duplication, or not. - Duplicating callbacks is usually an error. When it is intentional - it's a smell of a bad design and can be approached without abusing this "feature". My suggestion is: do not allow duplicating callbacks in one callback call, like it is not allowed in separate callbacks call.
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