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13 lines
1.5 KiB
Markdown
13 lines
1.5 KiB
Markdown
# @dynamicCallable Implementation Requirements
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If a type is marked with the `@dynamicCallable` attribute, it must provide a valid implementation of `dynamicallyCall(withArguments:)`, `dynamicallyCall(withKeywordArguments:)`, or both. If it fails to do so, an error will be reported at compile-time. Note that an implementation of `dynamicallyCall(withKeywordArguments:)` is required to support calls with keyword arguments.
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To be considered valid, an implementation of `dynamicallyCall(withArguments:)` must:
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- Be an instance method. `static` or `class` implementations are not allowed.
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- Have an argument type which conforms to the `ExpressibleByArrayLiteral` protocol. Often, this will be the built in `Array` type.
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- The return type of `dynamicallyCall(withArguments:)` may be any valid type.
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To be considered valid, an implementation of `dynamicallyCall(withKeywordArguments:)` must:
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- Be an instance method. `static` or `class` implementations are not allowed.
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- Have an argument type which conforms to the `ExpressibleByDictionaryLiteral` protocol. This can be `Dictionary`, `KeyValuePairs` (which may be used to support duplicated keyword arguments), or some other conforming type.
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- The `Key` associated type of the argument type must conform to the `ExpressibleByStringLiteral` protocol. This type is used to represent the dynamic argument keywords.
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- The `Value` associated type of the argument type and the return type of `dynamicallyCall(withKeywordArguments:)` may be any valid types. |