Make equality works on noop callbacks of same type

[cecton]

Description

This make Callbacks NOOP equal to other noops of the exact same type.

Checklist

• I have reviewed my own code
• I have added tests

[github-actions]

Visit the preview URL for this PR (updated for commit 28fc872):

https://yew-rs-api--pr3430-callback-eq-hlry4bwa.web.app

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[github-actions]

Benchmark - SSR

Yew Master

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	366.367	422.684	391.730	19.106
Hello World	10	590.404	705.993	643.723	40.090
Function Router	10	2103.914	2423.634	2223.732	100.976
Concurrent Task	10	1008.091	1010.382	1009.530	0.749
Many Providers	10	1418.927	1568.270	1508.135	56.420

Pull Request

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	375.312	430.253	399.060	22.779
Hello World	10	593.663	754.542	675.011	53.266
Function Router	10	2191.260	2534.028	2368.499	119.912
Concurrent Task	10	1007.654	1010.877	1009.217	0.927
Many Providers	10	1499.948	1719.462	1595.731	74.449

[github-actions]

Size Comparison

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	102.914	102.914	0	0.000%
boids	175.670	175.670	0	0.000%
communication_child_to_parent	95.299	95.299	0	0.000%
communication_grandchild_with_grandparent	109.045	109.045	0	0.000%
communication_grandparent_to_grandchild	105.718	105.718	0	0.000%
communication_parent_to_child	92.793	92.793	0	0.000%
contexts	113.458	116.263	+2.805	+2.472%
counter	89.196	89.196	0	0.000%
counter_functional	89.934	89.934	0	0.000%
dyn_create_destroy_apps	92.319	92.319	0	0.000%
file_upload	103.514	103.514	0	0.000%
function_memory_game	174.635	174.635	0	0.000%
function_router	353.852	356.313	+2.462	+0.696%
function_todomvc	163.495	163.495	0	0.000%
futures	227.446	227.446	0	0.000%
game_of_life	112.218	112.218	0	0.000%
immutable	188.789	188.789	0	0.000%
inner_html	85.980	85.980	0	0.000%
js_callback	113.464	113.464	0	0.000%
keyed_list	201.211	201.211	0	0.000%
mount_point	89.188	89.188	0	0.000%
nested_list	114.613	114.613	0	0.000%
node_refs	96.287	96.287	0	0.000%
password_strength	1721.308	1721.308	0	0.000%
portals	98.366	98.366	0	0.000%
router	319.828	322.211	+2.383	+0.745%
simple_ssr	144.247	144.247	0	0.000%
ssr_router	391.655	394.117	+2.462	+0.629%
suspense	119.058	119.058	0	0.000%
timer	91.797	91.797	0	0.000%
timer_functional	100.498	100.498	0	0.000%
todomvc	143.686	143.686	0	0.000%
two_apps	89.897	89.897	0	0.000%
web_worker_fib	138.891	138.891	0	0.000%
web_worker_prime	190.393	190.393	0	0.000%
webgl	88.552	88.552	0	0.000%

⚠️ The following example has changed its size significantly:

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
contexts	113.458	116.263	+2.805	+2.472%

[its-the-shrimp]

Is there really no other solution other than unwrapping and modifying a HashMap in a RefCell? that seems to me like too much work for a Default::default() value

[cecton]

Since the function is doing nothing I think it might be possible to do something with unsafe that would be much faster? But I'm really no expert so I won't write that lol

One alternative would be to wrap the Rc into an Option like this:

pub struct Callback<IN, OUT = ()> {
    /// A callback which can be called multiple times
    pub(crate) cb: Option<Rc<dyn Fn(IN) -> OUT>>,
}

(Or using an enum instead of struct)

[cecton]

But I'm afraid using Option will have a cost at runtime because every call will need to check the option.

[ranile]

What's the rationale behind this? No two closures are the same so why should two callbacks holding different closures be the same? Two Callbacks are the same if they have the same closure and that makes sense to me

[cecton]

@hamza1311 The case of the noop callback is very particular. Normally we should use Option<Callback> but sometimes you might want to create a component that forces the user to provide a callback. And if the user really wants to provide no callback at all, they would use noop.

Now the thing is that if they write this in their code:

<MyComponent
    onchange={Callback::noop()} />

The component will get updated all the time because the callback is re-created every time.

[cecton]

heh, I just bumped into #3395 and it clearly relates to my story

So maybe there is no need for making noop equal to other noops.

[cecton]

I'm closing this for now because I'm not sure. Anybody can re-open this ticket if they want.