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Parse, don't validate (2019)

(lexi-lambda.github.io)
398 points declanhaigh | 1 comments | 07 Mar 23 08:47 UTC | HN request time: 0.216s | source
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kybernetikos ◴[07 Mar 23 13:41 UTC] No.35055198[source]▶
This is obviously good advice almost all of the time.

However, I have had to deal occasionally with http libraries that tried to parse everything and would not give you access to anything that they could not parse. This was incredibly frustrating for corner cases that the library authors hadn't considered.

If you are the one who is going to take action on the data, parse don't validate is the correct approach. If you are writing a library that deals with data that it doesn't fully understand, and you're handing that data to someone else to take action with, then it may not always be the right approach.

replies(2): >>35056991 #>>35059019 #
1. lexi-lambda ◴[07 Mar 23 18:24 UTC] No.35059019[source]▶
I discussed how/why the point of this article is very much not to “parse everything” in this followup: https://lexi-lambda.github.io/blog/2020/01/19/no-dynamic-typ... In particular, it articulates precisely why it is fine to use relatively wide types for any input which the program treats opaquely, and it gives an example of how the same techniques can still be useful even in that context.