The type comes from XCTest. I’m trying to enumerate Objective-C methods in order to use them with XCTest in the open-source Swift version of XCTest, which needs the tests to be supplied as this type:
/// This is a compound type used by `XCTMain` to represent tests to run. It combines an /// `XCTestCase` subclass type with the list of test case methods to invoke on the class. /// This type is intended to be produced by the `testCase` helper function. /// - seealso: `testCase` /// - seealso: `XCTMain` public typealias XCTestCaseEntry = (testCaseClass: XCTestCase.Type, allTests: [(String, (XCTestCase) throws -> Void)]) Jeff Kelley slauncha...@gmail.com | @SlaunchaMan <https://twitter.com/SlaunchaMan> | jeffkelley.org <http://jeffkelley.org/> > On Nov 21, 2016, at 1:13 AM, Jacob Bandes-Storch <jtban...@gmail.com> wrote: > > "throws" is the part that's not representable in Obj-C. Why are you using it? > If you're interacting with method_getImplementation, you need to think like > the Obj-C runtime. > > https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtHowMessagingWorks.html#//apple_ref/doc/uid/TP40008048-CH104-SW1 > > <https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtHowMessagingWorks.html#//apple_ref/doc/uid/TP40008048-CH104-SW1> > > This works: > > typealias DescriptionMethod = @convention(c) (NSObject, Selector) -> > NSString > > let fn = > unsafeBitCast(method_getImplementation(class_getInstanceMethod(NSObject.self, > "description")), DescriptionMethod.self) > > fn(NSObject(), "description") as String > > > Jacob > > On Sun, Nov 20, 2016 at 9:41 PM, Jeff Kelley <slauncha...@gmail.com > <mailto:slauncha...@gmail.com>> wrote: > Still trying on this (copied the code directly, Foo is actually XCTestCase): > > typealias TestMethod = @convention(c) (XCTestCase) throws -> Void > > This seagulls the compiler with “error: '(XCTestCase) throws -> Void' is not > representable in Objective-C, so it cannot be used with '@convention(c)’”. > I’m trying to use it here: > > let testMethod: IMP = method_getImplementation(method) > > let test: TestMethod = unsafeBitCast(testMethod, > to: TestMethod.self) > > testMethods.append((methodName as String, test)) > > If I try to put the type directly in the call to unsafeBitCast(), the > compiler gives me an error: > > Attribute can only be applied to types, not declarations > > Thanks for your suggestions! I hadn’t seen @convention() before. > > > Jeff Kelley > > slauncha...@gmail.com <mailto:slauncha...@gmail.com> | @SlaunchaMan > <https://twitter.com/SlaunchaMan> | jeffkelley.org <http://jeffkelley.org/> >> On Nov 21, 2016, at 12:08 AM, Jacob Bandes-Storch <jtban...@gmail.com >> <mailto:jtban...@gmail.com>> wrote: >> >> For a function such as bar() above, the type you want to cast the IMP to >> would probably be "@convention(c) (Foo, Selector) -> ()". >> >> On Sun, Nov 20, 2016 at 9:05 PM, Jeff Kelley <slauncha...@gmail.com >> <mailto:slauncha...@gmail.com>> wrote: >> Thanks Jacob! I tried using unsafeBitCast, but it fails with the following: >> “fatal error: can't unsafeBitCast between types of different sizes”. I >> considered wrapping every call in a closure that calls objc_msgSend(), but >> alas, that’s not exposed to Swift. I have another approach in mind, so I’ll >> try that next. >> >> >> Jeff Kelley >> >> slauncha...@gmail.com <mailto:slauncha...@gmail.com> | @SlaunchaMan >> <https://twitter.com/SlaunchaMan> | jeffkelley.org <http://jeffkelley.org/> >>> On Nov 19, 2016, at 1:58 AM, Jacob Bandes-Storch <jtban...@gmail.com >>> <mailto:jtban...@gmail.com>> wrote: >>> >>> I imagine unsafeBitCast would be the way to go here. But are you assuming >>> that all of the instance methods have type "(Foo) throws -> Void" ? Or do >>> you somehow want to dynamically use the type information? >>> >>> Jacob >>> >>> On Fri, Nov 18, 2016 at 10:37 PM, Jeff Kelley via swift-users >>> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote: >>> Hello, >>> >>> I’m trying to enumerate the methods of a class in Swift using the >>> Objective-C runtime. Everything is working fine so far, except for the very >>> last step. Suppose I have a Swift class like this: >>> >>> class Foo: SomeSuperclass { >>> >>> @objc func bar() { >>> print("Hello, World!") >>> } >>> >>> } >>> >>> Using the Objective-C runtime methods, I can get the method with >>> class_copyMethodList and then get to the method’s implementation using >>> method_getImplementation. However, what I need to do next is to stick this >>> into a tuple that looks like this: >>> >>> typealias FooEntry = (fooClass: SomeSuperclass.Type, methods: [(String, >>> (Foo) throws -> Void)]) >>> >>> For now, the workaround is to make a static variable that returns all >>> of the entries: >>> >>> static var allEntries = { >>> return [ >>> ("bar", bar), >>> ] >>> } >>> >>> Is there any way to go from the raw IMP that I get back from the >>> runtime to the Swift type so I can construct this list dynamically? >>> >>> >>> Jeff Kelley >>> >>> slauncha...@gmail.com <mailto:slauncha...@gmail.com> | @SlaunchaMan >>> <https://twitter.com/SlaunchaMan> | jeffkelley.org <http://jeffkelley.org/> >>> >>> _______________________________________________ >>> swift-users mailing list >>> swift-users@swift.org <mailto:swift-users@swift.org> >>> https://lists.swift.org/mailman/listinfo/swift-users >>> <https://lists.swift.org/mailman/listinfo/swift-users> >>> >>> >> >> > >
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