Discussion on "Learn a little: Make metaprogramming possible in typescript class"

CHI PUTERA · 2021-10-22T16:07:01.315Z

So what is Metaprogramming? It's the ability of a program to read, analyze, and change its form dynamically. A program that can write a program. It's Magic in programming, and you are the wizard! The Challenge It won't be much of a hassle to do metap...

The code called "The Solution" doesn't even pass typechecking for me.

Am I missing something?

sample.ts(11,11): error TS2310: Type 'BirdModel' recursively references itself as a base type. sample.ts(35,24): error TS2693: 'Bird' only refers to a type, but is being used as a value here. /private/tmp/sample.js:23 var littleBird = new Bird(mrPelican); ^

ReferenceError: Bird is not defined at Object.<anonymous> (/private/tmp/sample.js:23:18) at Module._compile (node:internal/modules/cjs/loader:1241:14) at Module._extensions..js (node:internal/modules/cjs/loader:1295:10) at Module.load (node:internal/modules/cjs/loader:1091:32) at Module._load (node:internal/modules/cjs/loader:938:12) at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:83:12) at node:internal/main/run_main_module:23:47

Hi Dave, thanks for your comment. I think I've mistakenly replaced some of the code blocks with the wrong ones.

Kindly try copying the code block again, or you can get it from the repo here: github.com/chi-putera/practicality/blob/master/ja…

I'm confusing. Where is the metaprogramming part?

Maybe the title isn’t specific enough, I’ve changed it already. Thanks for your feedback.

CHI PUTERA Ah, I see. Thanks for clarifying. I'm also interested in this topic. Do you think we can do something like macro in typescript? Say I need to gather all file names in a given folder and make it be a union, something like:

type AllFileName = FilesAsUnion<`./path/to/folder`>

// emit: AllFileName = 'foo' | 'bar' | 'baz' | ...

of course, I can write a script to watch the folder and emit generated type. But it looks not that good

Manh Do Unfortunately, we can't define or inject types dynamically on the fly.

I don't think there is another way but to create a types-generator for that.

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Learn a little: Make metaprogramming possible in typescript class

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