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Stop writing CLI validation. Parse it right the first time

(hackers.pub)
203 points dahlia | 1 comments | 06 Sep 25 18:20 UTC | HN request time: 0s | source
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jmull ◴[06 Sep 25 22:14 UTC] No.45153373[source]▶
> Think about it. When you get JSON from an API, you don't just parse it as any and then write a bunch of if-statements. You use something like Zod to parse it directly into the shape you want. Invalid data? The parser rejects it. Done.

Isn’t writing code and using zod the same thing? The difference being who wrote the code.

Of course, you hope zod is robust, tested, supported, extensible, and has docs so you can understand how to express your domain in terms it can help you with. And you hope you don’t have to spend too much time migrating as zod’s api changes.

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bigstrat2003 ◴[07 Sep 25 02:16 UTC] No.45154791[source]▶
Yeah, the "parse, don't validate" advice seems vacuous to me because of this. Someone is doing that validation. I think the advice would perhaps be phrased better as "try to not reimplement popular libraries when you could just use them".
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1. yakshaving_jgt ◴[07 Sep 25 07:02 UTC] No.45156024[source]▶
Parsing includes validation.

The point is you don’t check that your string only contains valid characters and then continue passing that string through your system. You parse your string into a narrower type, and none of the rest of your system needs to be programmed defensively.

To describe this advice as “vacuous” says more about you than it does about the author.