mirror of
https://github.com/jashkenas/coffeescript.git
synced 2026-02-17 11:01:25 -05:00
137 lines
2.3 KiB
CoffeeScript
137 lines
2.3 KiB
CoffeeScript
ok(if mySpecialVariable? then false else true)
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mySpecialVariable = false
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ok(if mySpecialVariable? then true else false)
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# Existential assignment.
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a = 5
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a = null
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a ?= 10
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b ?= 10
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ok a is 10 and b is 10
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# The existential operator.
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z = null
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x = z ? "EX"
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ok z is null and x is "EX"
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i = 9
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func = -> i += 1
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result = func() ? 101
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ok result is 10
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ok (non ? existent ? variables ? 1) is 1
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# Only evaluate once.
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counter = 0
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getNextNode = ->
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throw "up" if counter
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counter++
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ok(if getNextNode()? then true else false)
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# Existence chains, soaking up undefined properties:
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obj = {
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prop: "hello"
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}
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ok obj?.prop is "hello"
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ok obj?['prop'] is "hello"
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ok obj.prop?.length is 5
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ok obj?['prop']?['length'] is 5
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ok obj?.prop?.non?.existent?.property is undefined
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ok obj?['non']?['existent'].property is undefined
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# Soaks and caches method calls as well.
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arr = ["--", "----"]
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ok arr.pop()?.length is 4
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ok arr.pop()?.length is 2
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ok arr.pop()?.length is undefined
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ok arr[0]?.length is undefined
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ok arr.pop()?.length?.non?.existent()?.property is undefined
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# Soaks method calls safely.
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value = undefined
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result = value?.toString().toLowerCase()
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ok result is undefined
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value = 10
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result = value?.toString().toLowerCase()
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ok result is '10'
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# Soaks inner values.
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ident = (obj) -> obj
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ok ident(non?.existent().method()) is undefined
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# Soaks constructor invocations.
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a = 0
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class Foo
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constructor: -> a += 1
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bar: "bat"
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ok (new Foo())?.bar is 'bat'
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ok a is 1
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# Safely existence test on soaks.
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result = not value?.property?
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ok result
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# Safely calls values off of non-existent variables.
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result = nothing?.value
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ok result is undefined
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# Assign to the result of an exsitential operation with a minus.
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x = null ? - 1
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ok x is - 1
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# Things that compile to ternaries should force parentheses, like operators do.
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duration = if options?.animated then 150 else 0
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ok duration is 0
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# function soak
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plus1 = (x) -> x + 1
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maybe_close = (f, arg) -> if typeof f is 'function' then () -> f(arg) else -1
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funcs = ->
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[
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(-> 37)
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'six times nine'
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(-> (-> plus1 4)?())
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]
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ok plus1?(41) is 42
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ok (plus1? 41) is 42
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ok plus2?(41) is null
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ok (plus2? 41) is null
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ok maybe_close(plus1, 41)?() is 42
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ok (maybe_close plus1, 41)?() is 42
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ok (maybe_close 'daddy would you like some sausage', 41)?() is null
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ok 2?(3) is null
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sum = 0
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(sum += (f? null ? 0)) for f in funcs?()
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ok sum is 42 |