now() returns not a relevant time if accessed from outside a reactive context

[rasentry]

When I use now in computed value and use it outside reaction it returns not relevant time.
see https://jsfiddle.net/pwcv8xsu/

[mattruby]

See this example: https://jsfiddle.net/pwcv8xsu/1/

Does that help you out?

[rasentry]

@mattruby No, because getter "time" is used not only inside reaction(autorun).

[mattruby]

@rasentry we're getting a little funky here, but you'll need to use keepAlive
See this example: https://jsfiddle.net/pwcv8xsu/3/

[mattruby]

Mobx will try to clean up computeds that are not being used in a reaction. So we're going to tell mobx not to do that with keepAlive. Note that keepAlive will return a disposer. You'll want to run that when/if you're done with that time.

[rasentry]

As I think it is not appropriate solution, because I need to take care about disposer.
In my project I use code from example from here https://mobx.js.org/refguide/extending.html
and there is no need disposer.

[mattruby]

I think that example is using reactions. If you use `reaction` or `autorun` mobx will take care of itself (for the most part). You're asking to hit a computed outside of a reaction, correct?

…

On Thu, Feb 16, 2017 at 12:30 PM, rasentry ***@***.***> wrote: As I think it is not appropriate solution, because I need to take care about disposer. In my project I use code from example from here https://mobx.js.org/refguide/extending.html and there is no need disposer. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#40 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAIrcusAmymdIrgD_BSXIl-vfY6UkAL4ks5rdJWtgaJpZM4MCtzo> .

-- -Matt Ruby- [email protected]

[rasentry]

Yes I use my gette inside and outside reaction. Inside reaction it works as designed, but when no reaction on this getter it returns old (cached) value.

[rasentry]

I think the problem is here https://github.com/mobxjs/mobx-utils/blob/master/src/from-resource.ts#L106
there is always returns cashed value, which updates only in reaction.
In example https://mobx.js.org/refguide/extending.html
there is check

if (this.atom.reportObserved()) {
            return this.currentDateTime;
        } else {
            // apparantly getTime was called but not while a reaction is running.
            // So, nobody depends on this value, hence the onBecomeObserved handler (startTicking) won't be fired
            // Depending on the nature
            // of your atom it might behave differently in such circumstances
            // (like throwing an error, returning a default value etc)
            return new Date();
        }

[mattruby]

I think the only way to get it working the way you want is to use `keepAlive`. I'm pretty sure it's going to end up being equivalent to any other solution you'd implement. If you built your own timer, you'd still have to dispose of the interval. I should note, that this is my first time playing with keepAlive. I haven't had to use it in production yet.

…

On Thu, Feb 16, 2017 at 12:36 PM, rasentry ***@***.***> wrote: Yes I use my gette inside and outside reaction. Inside reaction it works as designed, but when no reaction on this getter now inside it returns old value. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#40 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAIrcgRtilEJ2z1BhmV9wFrwr0S9HDl9ks5rdJcbgaJpZM4MCtzo> .

-- -Matt Ruby- [email protected]

[mweststrate]

Mm I think this can be fixed by checking if now () is being accessed from inside a derivation. Mobx.extras probably has some funky method to detect that. If the invocation isn't being tracked we can just return Date.now Op do 16 feb. 2017 19:41 schreef Matt Ruby <[email protected]>:

…

I think the only way to get it working the way you want is to use `keepAlive`. I'm pretty sure it's going to end up being equivalent to any other solution you'd implement. If you built your own timer, you'd still have to dispose of the interval. I should note, that this is my first time playing with keepAlive. I haven't had to use it in production yet. On Thu, Feb 16, 2017 at 12:36 PM, rasentry ***@***.***> wrote: > Yes I use my gette inside and outside reaction. Inside reaction it works > as designed, but when no reaction on this getter now inside it returns old > value. > > — > You are receiving this because you were mentioned. > Reply to this email directly, view it on GitHub > <#40 (comment)>, > or mute the thread > < https://github.com/notifications/unsubscribe-auth/AAIrcgRtilEJ2z1BhmV9wFrwr0S9HDl9ks5rdJcbgaJpZM4MCtzo > > . > -- -Matt Ruby- ***@***.*** — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#40 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ABvGhHnMU40Pp4g3UcsBLXz9DcJZ4-6sks5rdJg9gaJpZM4MCtzo> .

[rasentry]

@mweststrate As a temporary solution it is good, but I think now() should work like a "normal" Date.now(), isn't it?

[mweststrate]

Pushed a fix, will be part of next release