This changes 'if let' conditions to take general refutable patterns, instead of
taking a irrefutable pattern and implicitly matching against an optional.
Where before you might have written:
if let x = foo() {
you now need to write:
if let x? = foo() {
The upshot of this is that you can write anything in an 'if let' that you can
write in a 'case let' in a switch statement, which is pretty general.
To aid with migration, this special cases certain really common patterns like
the above (and any other irrefutable cases, like "if let (a,b) = foo()", and
tells you where to insert the ?. It also special cases type annotations like
"if let x : AnyObject = " since they are no longer allowed.
For transitional purposes, I have intentionally downgraded the most common
diagnostic into a warning instead of an error. This means that you'll get:
t.swift:26:10: warning: condition requires a refutable pattern match; did you mean to match an optional?
if let a = f() {
^
?
I think this is important to stage in, because this is a pretty significant
source breaking change and not everyone internally may want to deal with it
at the same time. I filed 20166013 to remember to upgrade this to an error.
In addition to being a nice user feature, this is a nice cleanup of the guts
of the compiler, since it eliminates the "isConditional()" bit from
PatternBindingDecl, along with the special case logic in the compiler to handle
it (which variously added and removed Optional around these things).
Swift SVN r26150
These APIs will be used for writing automation tools in Swift. Just
like other private APIs, this module is not exposed to extrenal users.
The primary motivation for doing instead of using NSCoder this is that
NSCoder does not work with structs and Swift containers. Using classes
for everything just to satisfy NSCoder forces unnatural code.
This API requires two times (!) less boilerplate than NSCoding, since
the same method is used for serialization and deserialization. This API
is also more type-safe, it does not require the user to write 'as' type
casts, unlike NSCoding.
Please take a look at
validation-test/stdlib/SwiftPrivateSerialization.swift to see the
intended use pattern.
The performance of the underlying implementation is already decent, and
there's a lot of room for improvement.
This is a re-commit of r25678, with a fix for 32-bit platforms.
Swift SVN r25877
The standard library has grown significantly, and we need a new
directory structure that clearly reflects the role of the APIs, and
allows future growth.
See stdlib/{public,internal,private}/README.txt for more information.
Swift SVN r25876
