Macros in Swift?

Does Swift currently support macros, or are there future plans to add support? Currently I'm scattering:

Log.trace(nil, function: __FUNCTION__, file: __FILE__, line: __LINE__)

In various places throughout my code.

In this case you should add a default value for the "macro" parameters.

Swift 2.2 and higher

func log(message: String,
        function: String = #function,
            file: String = #file,
            line: Int = #line) {

     print("Message \"\(message)\" (File: \(file), Function: \(function), Line: \(line))")
}

log("Some message")

Swift 2.1 and lower

func log(message: String,
        function: String = __FUNCTION__,
        file: String = __FILE__,
        line: Int = __LINE__) {

    print("Message \"\(message)\" (File: \(file.lastPathComponent), Function: \(function), Line: \(line))")
}

log("Some message")

This is what fatalError and assert functions do.

There are no other macros except the conditional compilation already mentioned in another answer.

The Apple docs state that:

> Declare simple macros as global constants, and translate complex macros into functions.

You can still use #if/#else/#endif - but my feeling is that they will not introduce macro functions, the language simply doesn't need it.

Since XCode 7.3, the __FILE__ __FUNCTION__ and __LINE__ compile-time constants have become the nicer-looking #file #function and #line respectively.

Here is an updated Swift 2 answer.

func LogW(msg:String, function: String = #function, file: String = #file, line: Int = #line){
	print("[WARNING]\(makeTag(function, file: file, line: line)) : \(msg)")
}

private func makeTag(function: String, file: String, line: Int) -> String{
    let url = NSURL(fileURLWithPath: file)
    let className = url.lastPathComponent ?? file
    return "\(className) \(function)[\(line)]"
}

Example of use:

LogW("Socket connection error: \(error)")

lastPathComponent needs an NSURL, so I changed the above code to this:

func log(message: String,
    function: String = __FUNCTION__,
    file: String = __FILE__,
    line: Int = __LINE__) {
    
        let url = NSURL(fileURLWithPath: file)
    
        print("Message \"\(message)\" (File: \(url.lastPathComponent ?? "?"), Function: \(function), Line: \(line))")
}

log("some message")

There is way to use macros on swift (but this used in Mixed of objective c and swift)

declare your macros into Project-name-Bridging-Header.h

#define  YOUR_MACRO @"Description"

or create separate header file for macros "macros.h"

import this header "macros.h" in to your Bridging-Header.h file..

now just save your project your macros will came in swift file ..

if you don't wanna object c code on your swift project... just create dummy cocoa touch classes it will create bridging header then use my way...

Macros are evil, but sometimes you just need them. For example, I have

struct RegionEntity {
    var id: Int!
}

And I want to place instances of this struct to Set. So I have to conform it to Hashable protocol.

extension RegionEntity: Hashable {
    public var hashValue: Int {
        return id
    }
}

public func ==(first: RegionEntity, second: RegionEntity) -> Bool {
    return first.id == second.id
}

Great. But what if I have dozens of such structs and the logic is the same? Maybe I can declare some protocol and conform it to Hashable implicitly. Let's check:

protocol Indexable {
    var id: Int! { get }
}

extension Indexable {
    var hashValue: Int {
        return id
    }
}

func ==(first: Indexable, second: Indexable) -> Bool {
    return first.id == second.id
}

Well, it works. And now I'm gonna conform my struct to both protocols:

struct RegionEntity: Indexable, Hashable {
    var id: Int!
}

Nope. I can't do that, because Equatable requires == operator with Self and there is no == operator for RegionEntity. Swift forces me to copy-paste confirmation code for each struct and just change the name. With macro I could do that with only one line.

Swift doesn't support macros because it would conflict with type-safety.