R
roblox-ts•2mo ago
May

Charm Questions

I'm not sure if this has been discussed before but I have three questions about charm: 1. What happens if you want to assign nil (undefined) to an atom? Do you have to attach a function that returns nil (or undefined)? 2. What if an atom stores a function? Do you need to chain a function inside a function? 3. What happens if your effect callback uses a dependency conditionally? How will charm know about that dependency if the dependency does not get read from/written to the first time the callback is executed? Thank you in advance for the help!
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18 Replies
May
MayOP•2mo ago
cc @LITTENSY
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Unknown User•2mo ago
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MayOP•2mo ago
Woah, i didn't know luau could differentiate between myAtom(nil) and myAtom()?? wth, is this a new typesolver feature or smth
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Unknown User•2mo ago
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MayOP•2mo ago
oh my gosh of course, i totally forgot about that lol also i dont understand what you mean by your third point.
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Unknown User•2mo ago
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MayOP•2mo ago
does that mean conditional dependencies dont get listened to for changes? i see
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Unknown User•2mo ago
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MayOP•2mo ago
(assuming they did not run) okay so just to be certain: if there is a dependency that is read from/written to conditionally, it is possible that updates to it will NOT cause the effect callback to execute, is that right?
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Unknown User•2mo ago
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MayOP•2mo ago
i see, okay so do you encourage developers to call atoms at the beginning of the callback at least once if they are run conditionally?
Tester
Tester•2mo ago
wdym?
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Unknown User•2mo ago
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May
MayOP•2mo ago
okay let me write out an example
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Unknown User•2mo ago
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MayOP•2mo ago
i see, that makes sense 
local visible = atom(true)
local count = atom(0)

charm.effect(function()
    if visible() then
        print("Current count is:", count())
    else
        print("Count is hidden")
    end
end)

-- This will rerun the effect and print the new count
count(1)

-- This will rerun the effect and print "Count is hidden"
visible(false)

-- This will NOT rerun the effect, even though `count` changes
-- because `count()` was not accessed in the last run
count(2)
local visible = atom(true)
local count = atom(0)

charm.effect(function()
    if visible() then
        print("Current count is:", count())
    else
        print("Count is hidden")
    end
end)

-- This will rerun the effect and print the new count
count(1)

-- This will rerun the effect and print "Count is hidden"
visible(false)

-- This will NOT rerun the effect, even though `count` changes
-- because `count()` was not accessed in the last run
count(2)
@Tester (Ping in reply pls!)
Tester
Tester•2mo ago
it recaptures atoms after change
May
MayOP•2mo ago
hmm i can kinda see why my example wont really come up as being 'an issue' in the real world okay thank you so much guys! i rlly appreciate it:)

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