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d20414e87d
* add sketch for drop * add drop example * correct drop ordering * fix: simplify drop and add to deleter * docs: add drop docs * fix: use a sound lifetime var
24 lines
590 B
Markdown
24 lines
590 B
Markdown
# Drop
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One of the “special” interfaces implementable by any type in Carp is `drop`,
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the signature of which is `(Fn [&a] ())`. It takes a reference to a type and
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is run before that type is deleted. This is meant for types that need special
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treatment before being deallocated, such as files that need to be closed.
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```clojure
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(deftype A [])
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(defmodule A
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(sig drop (Fn [(Ref A)] ()))
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(defn drop [a]
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(IO.println "Hi from drop!"))
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)
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(defn main []
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(let [a (A)]
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()))
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```
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In the case above, `A.drop` will be run and `Hi from drop` will be printed
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when the `let` scope ends.
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