zewo / reflection

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Zewo

Zewo is a lightweight library for web applications in Swift.

What sets Zewo apart?

Zewo is not a web framework. Zewo is a lightweight library for web applications in Swift. Most server-side Swift projects use Grand Central Dispatch (GCD) as the concurrency library of choice. The drawback of using GCD is that its APIs are asynchronous. With async code comes callback hell and we all know it, it's no fun.

Node.js is the best example of how callbacks can be frustrating. Express.js creator TJ Holowaychuk wrote a blog post about Callback vs Coroutines in 2013 and one year later left the Node.js community in favor of Go. There were many reasons for that but one of the main reasons was the concurrency model. Sure we have futures and promises and functional reactive programming. They all mitigate the problem, but the async nature of the code will always be there.

At Zewo we use coroutines. Coroutines allow concurrency while maintaining synchronous APIs. We all learn how to program with synchronous code. We're used to reason about our code synchronously. Being able to use synchronous APIs makes the code much more readable and understandable. Coroutines are also faster than threads, because they live in user-space, unlike threads which are managed by the kernel.

Our implementation of coroutines (which is based on libdill) is single-threaded. This means that you don't have to worry about locks or race conditions. So your code is safer by default. To use all the CPU power available all you have to do is to replicate the work according to the number of logical CPUs available. As an example, this could mean running as many processes of your server as cores in your machine. Rob Pike, one of the creators of Go had a talk called Concurrency is not Parallelism that explains this concept very well. Go also has the philosophy:

Don't communicate by sharing memory. Share memory by communicating.

Like Go, instead of sharing memory and handling state we promote the use of CSP-style concurrency using channels. This pattern brings the abstractions used on the development of distributed systems closer to the way we're used to think about communication. It also aligns well with Swift's mindset of immutability and value types. All of these things contributes to a distinct experince on the server-side Swift.

With Zewo you get:

• Go-style concurrency
• Synchronous APIs
• Incredible performance
• Safer applications
• Scalable systems
• Cleaner code
• Proper error handling
• No callback hell
• No race conditions

Support

If you have any trouble create a Github issue and we'll do everything we can to help you. When stating your issue be sure to add enough details and reproduction steps so we can help you faster. If you prefer you can join our Slack and go to the #help channel too.

Community

We have an amazing community of open and welcoming developers. Join us on Slack to get to know us!

License

All Zewo modules are released under the MIT license. See LICENSE for details.

reflection's Issues

Reflection of deep nested object

I have a complex classes of this type

`public class Info: Codable {

public var user: UserModel?
public var data: String?

}

public struct UserModel: Codable {
public var username: String?
public var name: String?
}`

I want to access sub properties in this way "user.info", is it possibile?

var obj = Info() let xxx: String? = try? get("user.info", from: obj)

'Hashable.hashValue' is deprecated as a protocol requirement

Swift Compiler Warning has occurred.

Message:

• 'Hashable.hashValue' is deprecated as a protocol requirement; conform type 'HashedType' to 'Hashable' by implementing 'hash(into:)' instead

File location:

• Properties.swift / HashedType / hashValue

Classes as well as Structs

Any chance this can work with classes as well as structs? If not, is it because the functionality isn't possible, or just needs a PR?

Issue in SwiftKVC caused by Reflection library

Hey the library SwiftKVC has an issue caused by your Reflection library with iOS 12 beta 2 and Xcode 10 beta 2.
bradhilton/SwiftKVC#10
do you have any idea how to solve this?
thank you :)

Missing description under title

Should be:

Reflection provides an API for advanced reflection at runtime including dynamic construction of types.

Xcode 11 'Package Resolution failed' error

Add Package Dependency feature in Xcode 11 gives the following error:

The package dependency graph can not be resolved; unable find any available tag for the following requirements:

https://github.com/Zewo/Reflection.git — 0.18.1..<1.0.0

and I found that advice given to a similar error:

I believe this is because you've missed out the products and targets section in the Package.swift file. A simple example can be found in JGProgressHUD's Packages.swift

Swift 4.2

The nominal type descriptor metadata is going away completely in 4.2. So there's no longer a way to get field names and types with the method this package uses. There is a new runtime method swift_getFieldAt to retrieve this data, however it uses C++ std::function and is not callable from Swift. You'd need to create a C++ wrapper that exposes a C API to use this. I've opened a PR on Swift to fix this (and make the method easily callable from Swift), but I'm not sure if they will do anything about it: swiftlang/swift#15565. Thought I would share this info, thanks for the cool package!

Swift 4.1

Getting some crashes in Swift 4.1 around:

    var numberOfFields: Int {
        return Int(pointer.pointee.numberOfFields)
    }

in NominalTypeDescriptor, trying to dig into what may have changed but I think there was some memory layout changes!

How to handle Default values?

What if I have a declaration of a struct like this?

struct Person {
    var firstName: String = "Max"
    var lastName: String = "Alexander"
    var age: Int = 12
    var phoneNumber: String = "4159300285"
}

But then I try to construct it using:

let person: Person = try! construct(dictionary: [:])

It'll tell me there are missing keys from the input dictionary. I understand the error. But what if the keys are missing and I prefer to construct it with their default values that I have declared above?

Is there any way to handle this sort of behavior?

Crashes if classes inherit from NSObject.

If you try to reflect an instance of a class that inherits from NSObject, it will crash while accessing a null pointer when trying to reflect NSObject.

The minimal example would be:

class Foobar: NSObject {
    var stringProperty: String = "foobar"
}

let instance = Foobar()
try! properties(instance)

I have an example traceback in the attached screenshot. I tried with Swift 3.3 and Swift 4.1.

I see that there's already a workaround in the superclass reflection where we exclude the SwiftObject superclass:

Reflection/Sources/Reflection/Metadata+Class.swift

Line 22 in 1414e12

guard let superclass = superclass, String(describing: unsafeBitCast(superclass.pointer, to: Any.Type.self)) != "SwiftObject" else {

Would it make sense to exclude the NSObject superclass in the same way? Or is reflecting on classes inherited from NSObject in general not supported?

Would you be willing to already make an alpha Swift 4.0-branch?

Please? O:-)

edit

I'm already doing an attempt in my fork and the only test that's failing so far is testConstructAnyType().

Xcode 10.2 and Swift 5 problem building

Hi,

on Xcosw 10.2 and in particular with swift 5 there's a serious problem.
Here is:
Undefined symbols for architecture x86_64: "_swift_getFieldAt", referenced from: closure #1 (Swift.Int) -> (Swift.String, Any.Type) in (extension in Reflection):Reflection.NominalType.fieldNamesAndTypes(for: Any.Type) -> [(Swift.String, Any.Type)]? in NominalType.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

I've searched on google and found this blog post:

https://www.jishuwen.com/d/2Elq/zh-hk
alibaba/HandyJSON#307

Can you help?

Thanks.

support cocoapods and IOS Project?

this could support cocoapods and IOS Project?