yelouafi/redux-saga

An alternative side effect model for Redux apps

Christian Maniewski

@chmanie

Yeah, I guess you’re right, I probably won’t be needing anything besides string comparisons

Christian Maniewski

@chmanie

I have another question: I’m not entirely sure around the workings of the try-finally construct when using a while(true). How do we get in the finally clause there?

(third example in the eventChannel: https://github.com/redux-saga/redux-saga/blob/master/docs/advanced/Channels.md#using-the-eventchannel-factory-to-connect-to-external-events)

Tormen Raßmann

@trassmann

from w3c: The finally statement lets you execute code, after try and catch, regardless of the result.

i dont understand the question, do you mean why it triggers?

Christian Maniewski

@chmanie

Yeah, what kicks us out of the while(true)

Oh, ok probably an error is thrown

Tormen Raßmann

@trassmann

when any code wrapped in a try block throws an exception the catch/finally will trigger

Christian Maniewski

@chmanie

So take(END) actually throws an error?

Tormen Raßmann

@trassmann

END just kills all takers on the standard channel

so take(END) is kinda redundant

Christian Maniewski

@chmanie

But then it’s caught internally by redux-saga somehow, I guess

Tormen Raßmann

@trassmann

its contradictary actually

A Flores

@unflores

right but to get to finally there has to be an exception thrown right?

Tormen Raßmann

@trassmann

right but to get to finally there has to be an exception thrown right?

yea

Christian Maniewski

@chmanie

Note also we're executing the whole while (true) {...} loop inside a try/finally block. When the interval terminates, the countdown function closes the event channel by invoking emitter(END).

Tormen Raßmann

@trassmann

But then it’s caught internally by redux-saga somehow, I guess

probably you are getting an exception because take(END) is not meant to be done, thats what take.maybe is for

Christian Maniewski

@chmanie

Yeah, I think I was just confused that there’s no error but redux-saga seems to catch that specific one for me

A Flores

@unflores

er nm what am I saying.

This message was deleted

try{ console.log('derp') } catch(err){console.log(err)}finally{console.log('yerp')}

gives 'derp' 'yerp'

so no need for an exception to be thrown

Christian Maniewski

@chmanie

wait, where’s your while(true) @unflores

A Flores

@unflores

I was confused about the usage of finally, no idea how they drop out of while(true) maybe a break somehow?

Christian Maniewski

@chmanie

An exception is needed to break out of this

Tormen Raßmann

@trassmann

so no need for an exception to be thrown

yea it also executes when the try block finishes executing, but it wont in this case since its an endless loop

(unless an exception is thrown)

Christian Maniewski

@chmanie

Can I take the same action multiple times from a channel? It seems the first taker gets it and after that it’s removed from the buffer, is that right?

Christian Maniewski

@chmanie

Yep, FIFO

Another thing. As far as I can see, when I emit an Error in an eventChannel and then take from that channel it should throw, right? This doesn’t really work for me. Meaning it just doesn’t throw it seems

Christian Maniewski

@chmanie

Tests say it shoud 🤔

Christian Maniewski

@chmanie

It does, I’m just doing it wrong it seems

Tormen Raßmann

@trassmann

Can I take the same action multiple times from a channel? It seems the first taker gets it and after that it’s removed from the buffer, is that right?

yea, unless you use multicast channel, then every taker is triggered

Christian Maniewski

@chmanie

:+1:

Oh now all these names make much more sense

Tormen Raßmann

@trassmann

redux saga has an amazing api IMO but it takes some getting used to that way of doing stuff

A Flores

@unflores

Does anyone know where the docs for multicast are? I would like to look them over, https://redux-saga.js.org/docs/introduction/ doesn't have a section that screams multicast at me

Tormen Raßmann

@trassmann

@unflores the docs are a bit behind i'm afraid

but ask away, the maintainers and users hang out here and are likely to be able to answer your questions

A Flores

@unflores

Ah ok. Cool. Honestly I wanted to look at it to have a few ideas about what the usage would be. I'm not very creative :)

I tried digging through the code recently and I was a little lost.

Tormen Raßmann

@trassmann

i asked about it in december here

A Flores

@unflores

I assume it gives you the possiblity to treat sagas as a message broker. I have a hard time arriving at a good use case, but like I said, creativity problems :)

ah, cool. thanks for the info

g. nicholas d'andrea

@gnidan

hey folks... does anyone happen to have a resource that describes the lifecycle of an action in the context of put/take? I'm having a hard time reasoning about put vs. putResolve, e.g., so more generally, I'm hoping to find a collection of sequence diagrams or something like that

Tim De Groote

@timdegroote

Hey everyone, small question: Does redux-saga always run its effects synchronously? Or does it sometimes wait to execute its effects. The reason why I'm askin is because I have a case where two actions are called (ACTION1 and ACTION2). ACTION1 is dispatched first and ACTION2 shortly after. Now I need a saga to respond to ACTION1 before ACTION2 hits the reducer but from my console it looks like the saga is triggered when both ACTION1 and ACTION2 are already handled by the reducer.

Amir Off

@amiroffme

Hello everyon,

I need help with this redux-saga/redux-saga#1762

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