Clojurians Log v2
reagent 2025-11-05
I have a reagent puzzle, feel free to see if you can figure it out before me.
In a nut shell, this https://github.com/pyregence/pyregence/commit/b9c21052f4f3ba617f0615f79051cb8e6ed3f7da#r169744147 spells out my mystery. To rephrase, the fn i passed to the reagent classes :reagent-render wasn't being passed the same args the component was e.g (defn f [args] (r/clreate-class {:reagent-render (fn [args] ;; args were nil here but f was passed args .
So i did some hacking and i discovered that down the call pipeline it looks like we did this (reagent.dom/render (cmpt instead of this [cmpt ... here where https://github.com/pyregence/pyregence/commit/cea4006be54ba7255848309bc4b2789f0efc7a66#r169744498, and where i change to to be a vector, and then it works.
If anyone can bring come clarity to this, it would be appreciated.
Just never use (...) with Reagent components, ever. :) It's reasonably well documented.
wrap-page is a form-2 component, but when you call it as a plain function it just returns another function.
So you end up with (reagent.dom/render some-fn ...).
When a function is passed to render, it gets called as a plain function as well, so it effectively turns into (render [:div ... from wrap-page ...] ...).
That might not be a problem by itself though since wrap-page is not reactive.
However, when you use #((uri->root-component-h uri) params), you end up with a function that immediately calls a view function on parameters.
That view function is also a form-2 component. When you call it, it returns a closure with some parameters. But since you didn't use Hiccup, just closures, Reagent itself has never even seen those params - it cannot pass them again, they don't exist for Reagent.
In other words, at some point you end up with (wrap-page (fn [params] ...)), but those params cannot come from anywhere.
@hhausman I wouldn't say it nailed anything, to be honest... It just talked about efficiency and reactivity. The actual reason I outlined above isn't in the LLM-generated text at all.
> If you use (my-component props), the function my-component is called immediately, and its result (a data structure representing the UI) is placed directly into the parent's data structure.
vs.
> However, when you use #((uri->root-component-h uri) params), you end up with a function that immediately calls a view function on parameters.
🤷 simple_smile
@p-himik - you know I think you're one of the most helpful people around.
> and its result (a data structure representing the UI) is placed directly into the parent's data structure Which is just false in the case of anything but form-1 components - there is no data structure, it's just a closure that expects arguments that never come. The context that the LLM has provided for that statement is just efficiency, not correctness. > you know I think you're one of the most helpful people around Appreciate it. :)