[swift-evolution] [Pitch] Renaming sizeof, sizeofValue, strideof, strideofValue

[Erica Sadun]

Supporting Dave A, type-based calls are much more likely to be used than instance calls, unlike with dynamicType/type(of:)

Term	stdlib search	gist search	Google site:github +swift
sizeof	157	169	4880
sizeofValue	4	34	584
alignof	44	11	334
alignofValue	5	5	154
strideof	347	19	347
strideofValue	4	5	163
Type-based calls like sizeof() are poor candidates for parameter labels. While it's acceptable to write sizeof(Int), but one must write size(of: Int.self) (with the trailing self) when the function has a label. For this reason, this proposal prefers using no-label calls for types (otherwise they would have been ofType) and labeled calls for values:

print(sizeof(Int)) // works
print(sizeof(Int.self)) // works

func withoutLabel<T>(thetype: T.Type) -> Int { return sizeof(T) }
func withLabel<T>(label label: T.Type) -> Int { return sizeof(T) }


// Works
print(withoutLabel(Int))

// Works
print(withLabel(label: Int.self))

// Does not work
// error: cannot create a single-element tuple with an element label
// print(withLabel(label: Int)) 


So with this in mind:

/// Returns the contiguous memory footprint of `T`.
///
/// Does not include any dynamically-allocated or "remote" storage.
/// In particular, `size(X.self)`, when `X` is a class type, is the
/// same regardless of how many stored properties `X` has.
public func size<T>(_: T.Type) -> Int

/// Returns the contiguous memory footprint of  `T`.
///
/// Does not include any dynamically-allocated or "remote" storage.
/// In particular, `size(of: a)`, when `a` is a class instance, is the
/// same regardless of how many stored properties `a` has.
public func size<T>(of: T) -> Int

/// Returns the least possible interval between distinct instances of
/// `T` in memory.  The result is always positive.
public func spacing<T>(_: T.Type) -> Int

/// Returns the least possible interval between distinct instances of
/// `T` in memory.  The result is always positive.
public func spacing<T>(of: T) -> Int

/// Returns the minimum memory alignment of `T`.
public func alignment<T>(_: T.Type) -> Int

/// Returns the minimum memory alignment of `T`.
public func alignment<T>(of: T) -> Int
-- E
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