Allow default nil values for optional properties
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This adds underscored initializers that let library users add `= nil` to declarations of optional `@Option` and `@Argument` properties. Previously, default values have been available for properties of non-optional types only. These new initializers use `_OptionalNilComparisonType` as the wrapped value parameter, so only a `nil` literal is acceptable in the default value position. This avoids the problem of declaring an optional property with a non-`nil` default, which ends up negating the purpose of an optional.
These are sprinkled in where they seem natural, to illustrate how types can be initialized.
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@swift-ci Please test |
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Just wondering, why is this desired? Are we expecting an upcoming language mode where |
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This adds underscored initializers that let library users add
= nilto declarations of optional@Optionand@Argumentproperties. Previously, default values have been available for properties of non-optional types only.These new initializers use
_OptionalNilComparisonTypeas the wrapped value parameter, so only anilliteral is acceptable in the default value position. This avoids the problem of declaring an optional property with a non-nildefault, which ends up negating the purpose of an optional.Checklist