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From: Carlos R. <car...@gm...> - 2005-01-06 09:57:40
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Hi all, I've been insisting on this point (Postel's Law as applied to software) but I feel that my argument hasn't been convincing. To be sincere, it's my fault: I haven't presented the argument in a convincing way. Let's try to correct it. Postel's Law is one of foundations of Internet design. Why does it work? Simple: it creates an asymmetry on the strictness requirements. As a programmer, you must make sure that you play nice. It's something that *you can control*. But you can't control what other pieces of software do, so you have to be more open minded about what do they send to you. Other people may have done it in a slightly different (but incompatible) way, based on a perfectly reasonable interpretation of the same standard. Postel's Law is just the realization of an inherent asymmetry in the problem space. I believe that Postel's Law principles should apply to any complicate enough piece of software (and that includes anything bigger than a few dozen lines). The reason is: the programmer only does have control over the interface provided by software he's writing, but no control over the interfaces it uses. One of the consequences of failing to meet Postel's Law guidelines in software is the usual fingerpointing exercise. If two pieces of software do not match, it's usual to hear heated arguments about who did wrong, and who should correct it. But what if both sides have reasonable arguments? Simple: the client side must adapt to it, as reasonably as possible. It's simpler done this way, and consistent. Better, it avoids surprises. In SQLObject's case, I believe that the principle is simple. If the programmer declared an IntCol, it's reasonable to enforce it. But there's no way one can enforce the same kind of strictness about the DB driver. I'm not saying this in the strict sense of the int() conversion, I'm talking about the generic case. That's why I believe SQLObject should perform automatic coercion on all the data it fetches from the database. -- Carlos Ribeiro Consultoria em Projetos blog: http://rascunhosrotos.blogspot.com blog: http://pythonnotes.blogspot.com mail: car...@gm... mail: car...@ya... |
