yew-macro: Handling of boolean properties

[Follpvosten]

Description

I'm submitting a feature request (I intend to work on this myself if I can find the time).

• Since bool defaults to false, the property being missing already implies false, which is great. However, I'd really like it to work the other way around too: If a bool property is present, it should imply true (meaning I can write <MyComp myprop /> instead of <MyComp myprop=true />).

[jstarry]

These both sound like great features, would gladly review PRs to fix them! Could you please split this issue into two? One for boolean handling and one for Option conversion?

[Follpvosten]

Alright, I'll do that now.

I actually came across a similar situation to what you described in #756 - I have something like:

let placeholder = if something { "something" } else { "something else" };
html! {
    <input type="text" /* ... */ placeholder=placeholder />
}

Being able to omit the =placeholder if there's a variable with the exact name of the property in scope would be a very nice improvement. I guess I'll create an issue for that as well.

[samuelvanderwaal]

Missing label:

• good first issue

[CalliEve]

Hi! I am still pretty junior, but I am interested to work on this if it is something that is still wanted? I see that something similar will be done with #769 with the syntax there potentially colliding for the syntax here?

Also after looking at the code I see that the lib doesn't "know" what type a prop is till the to_tokens call in the HtmlComponent struct (I could be wrong in this). While I could set the value to true automatically and then check over there if it is the correct type, I don't know if this will result in a well-understandable error in case the type of the prop isn't a bool.

[jstarry]

@Baev1 thanks for taking a look, you're totally right about that. I think we could only have this special handling for boolean html elements:

yew/crates/macro/src/html_tree/html_tag/tag_attributes.rs

Lines 27 to 49 in 22904eb

	static ref BOOLEAN_SET: HashSet<&'static str> = {
	HashSet::from_iter(
	vec![
	"async",
	"autofocus",
	"controls",
	"default",
	"defer",
	"disabled",
	"hidden",
	"ismap",
	"loop",
	"multiple",
	"muted",
	"novalidate",
	"open",
	"readonly",
	"required",
	"selected",
	]
	.into_iter(),
	)
	};

Even then, it's probably not so useful because it's much easier to enable/disable these types of attributes using a dynamic bool.

I think it's safe to close this, so I'll do so. @Baev1 are you specifically interested in helping with the macro or would you be interested in helping on other issues? We can discuss in the gitter room if you want!