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49 lines
974 B
Markdown
49 lines
974 B
Markdown
# Effects
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Effects are functions that are ran in response to source updates. They are
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A source and effect is analogous to a signal and connection.
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Effects are created using `effect()`.
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```lua
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local source = vide.source
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local effect = vide.effect
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local count = source(0)
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effect(function()
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print("count: " .. count())
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end)
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-- "count: 0" printed
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count(1)
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-- "count: 1" printed
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```
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Any source read inside an effect is tracked and will rerun the effect when
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that source is updated.
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Derived sources are also tracked, it doesn't matter how deeply nested
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inside a function a source is.
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```lua
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local source = vide.source
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local effect = vide.effect
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local count = source(1)
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local doubled = function()
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return count() * 2
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end
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effect(function()
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print("doubled count: " .. doubled())
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end)
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-- "doubled count: 2" printed
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count(2)
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-- "doubled count: 4" printed
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```
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If a source is updated with the same value it already had, it will not rerun
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effects depending on it.
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