any wisdom about sharing "common" overloads/extensions in base libraries?


(David Baraff) #1

I posted this on Apple’s developer forums, and someone suggested trying this here.
Basically, see https://forums.developer.apple.com/thread/80349

but in a nutshell: consider that a widely used class/struct (such as CGPoint) is missing some “obvious” functionality [don’t debate that part, just go with it for now], such as the ability to scale a point by a scalar using * as an operator: so in my awesome library “GeometryBase” I write

  public func * (left: CGPoint, right: double) -> CGPoint {
      return CGPoint(x: right*left.x, y: right*left.y)
  }

Why public? Well, of course, because I want to use library GeometryBase in many apps or other libraries, and now this overload exists in only one place.

But other bright people have the same idea, and now I want to use their libraries. (some of them in my company, some of them not.)

And now we’re stuck, because everyone is trying to make up for the same (perceived) lack and everyone wants them public so that they don’t have to keep sticking them in each library they write.

This is not a made up situation: many people even within one company trying to share code somewhat informally are going to write the same code to make using CGPoint/Size/Rect easier, and now we can’t share anything safely.

Anybody got some good ideas what to do about this?

[Same question could apply to adding extensions.]


(Travis Griggs) #2

I don’t have a good idea how to solve the problem. We dealt with this type of thing many years ago in Smalltalk systems.

Strategically, when I write application code for end user consumption, I will use my goodly sized library of base library extensions. But when I’m writing a framework to be used by other programmers, I swear off the extensions. If there is an extension that is just so essential, I’ll restrain its scope as much as possible, both with ACLs as well as obvious name prefixes:

  extension CGPoint {
    var radius_myFramework:CGFloat {
      return sqrt((self.x * self.x) + (self.y * self.y))
    }

This doesn’t do much for infix signatures though.

That said, I’m glad to have this problem in Swift. I’m willing to live with the hassle it can create. The gain is worth it. I hate that Python won’t let me extend base types.

···

On Jun 20, 2017, at 7:02 AM, David Baraff via swift-users <swift-users@swift.org> wrote:

I posted this on Apple’s developer forums, and someone suggested trying this here.
Basically, see https://forums.developer.apple.com/thread/80349

but in a nutshell: consider that a widely used class/struct (such as CGPoint) is missing some “obvious” functionality [don’t debate that part, just go with it for now], such as the ability to scale a point by a scalar using * as an operator: so in my awesome library “GeometryBase” I write

  public func * (left: CGPoint, right: double) -> CGPoint {
      return CGPoint(x: right*left.x, y: right*left.y)
  }

Why public? Well, of course, because I want to use library GeometryBase in many apps or other libraries, and now this overload exists in only one place.

But other bright people have the same idea, and now I want to use their libraries. (some of them in my company, some of them not.)

And now we’re stuck, because everyone is trying to make up for the same (perceived) lack and everyone wants them public so that they don’t have to keep sticking them in each library they write.

This is not a made up situation: many people even within one company trying to share code somewhat informally are going to write the same code to make using CGPoint/Size/Rect easier, and now we can’t share anything safely.

Anybody got some good ideas what to do about this?

[Same question could apply to adding extensions.]


(Tino) #3

This is not a made up situation: many people even within one company trying to share code somewhat informally are going to write the same code to make using CGPoint/Size/Rect easier, and now we can’t share anything safely.

Well, have a look at what C++ did: Nothing :wink: — and therefore, the world is littered with incompatible, trivial definitions of vectors, images, notes…

My favourite example are quaternions (just do a search for that term in Apples own frameworks…), so there is definitely an issue here.
The solution is quite easy, but that makes things really complicated: Just declare a standard (that's easy — so everyone wants to have his own one ;-).

Unless someone with outstanding reputation (sadly, Apple seems not to care for this) starts a project like Boost, we'll have to live with incompatibilities.

Tino


(Howard Lovatt) #4

There is a *bug* that the Swift people know about, but you are **meant** to
be able to do this:

ModuleA

A.swift

public protocol P {

func m() -> String

}

extension Int: P {

public func m() -> String { return "AP.m" }

}

ModuleB

B.swift

public protocol P {

func m() -> String

}
extension Int: P {

public func m() -> String { return "BP.m" }

}

ModuleC

A.swift

import ModuleA

func am(_ i: Int) -> String { return i.m() }

B.swift

import ModuleB

func bm(_ i: Int) -> String { return i.m() }

main.swift

let i = 0

print(am(i))
print(bm(i))

  -- Howard.

···

On 21 June 2017 at 00:02, David Baraff via swift-users < swift-users@swift.org> wrote:

I posted this on Apple’s developer forums, and someone suggested trying
this here.
Basically, see https://forums.developer.apple.com/thread/80349

but in a nutshell: consider that a widely used class/struct (such as
CGPoint) is missing some “obvious” functionality [don’t debate that part,
just go with it for now], such as the ability to scale a point by a scalar
using * as an operator: so in my awesome library “GeometryBase” I write

  public func * (left: CGPoint, right: double) -> CGPoint {
      return CGPoint(x: right*left.x, y: right*left.y)
  }

Why public? Well, of course, because I want to use library GeometryBase
in many apps or other libraries, and now this overload exists in only one
place.

But other bright people have the same idea, and now I want to use their
libraries. (some of them in my company, some of them not.)

And now we’re stuck, because everyone is trying to make up for the same
(perceived) lack and everyone wants them public so that they don’t have to
keep sticking them in each library they write.

This is not a made up situation: many people even within one company
trying to share code somewhat informally are going to write the same code
to make using CGPoint/Size/Rect easier, and now we can’t share anything
safely.

Anybody got some good ideas what to do about this?

[Same question could apply to adding extensions.]

_______________________________________________
swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users


(Travis Griggs) #5

Also, reading about Kotlin recently, I found the exposition of extensions interesting:

https://kotlinlang.org/docs/reference/extensions.html

In particular the part about them being resolved statically. I’ve wondered if this helps obviate this conflict problem, but I haven’t thought through it enough yet.

···

On Jun 20, 2017, at 2:25 PM, Travis Griggs <travisgriggs@gmail.com> wrote:

On Jun 20, 2017, at 7:02 AM, David Baraff via swift-users <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:

I posted this on Apple’s developer forums, and someone suggested trying this here.
Basically, see https://forums.developer.apple.com/thread/80349

but in a nutshell: consider that a widely used class/struct (such as CGPoint) is missing some “obvious” functionality [don’t debate that part, just go with it for now], such as the ability to scale a point by a scalar using * as an operator: so in my awesome library “GeometryBase” I write

  public func * (left: CGPoint, right: double) -> CGPoint {
      return CGPoint(x: right*left.x, y: right*left.y)
  }

Why public? Well, of course, because I want to use library GeometryBase in many apps or other libraries, and now this overload exists in only one place.

But other bright people have the same idea, and now I want to use their libraries. (some of them in my company, some of them not.)

And now we’re stuck, because everyone is trying to make up for the same (perceived) lack and everyone wants them public so that they don’t have to keep sticking them in each library they write.

This is not a made up situation: many people even within one company trying to share code somewhat informally are going to write the same code to make using CGPoint/Size/Rect easier, and now we can’t share anything safely.

Anybody got some good ideas what to do about this?

[Same question could apply to adding extensions.]

I don’t have a good idea how to solve the problem. We dealt with this type of thing many years ago in Smalltalk systems.

Strategically, when I write application code for end user consumption, I will use my goodly sized library of base library extensions. But when I’m writing a framework to be used by other programmers, I swear off the extensions. If there is an extension that is just so essential, I’ll restrain its scope as much as possible, both with ACLs as well as obvious name prefixes:

  extension CGPoint {
    var radius_myFramework:CGFloat {
      return sqrt((self.x * self.x) + (self.y * self.y))
    }

This doesn’t do much for infix signatures though.

That said, I’m glad to have this problem in Swift. I’m willing to live with the hassle it can create. The gain is worth it. I hate that Python won’t let me extend base types.


(David Baraff) #6

There is a *bug* that the Swift people know about, but you are **meant** to be able to do this:

Is there a plan to fix this?
If it worked properly this would be quite wonderful.

···

On Jun 20, 2017, at 6:59 PM, Howard Lovatt <howard.lovatt@gmail.com> wrote:

ModuleA
A.swift
public protocol P {
func m() -> String
}
extension Int: P {
public func m() -> String { return "AP.m" }
}
ModuleB
B.swift
public protocol P {
func m() -> String
}
extension Int: P {
public func m() -> String { return "BP.m" }
}
ModuleC
A.swift
import ModuleA
func am(_ i: Int) -> String { return i.m() }
B.swift
import ModuleB
func bm(_ i: Int) -> String { return i.m() }
main.swift
let i = 0
print(am(i))
print(bm(i))

  -- Howard.

On 21 June 2017 at 00:02, David Baraff via swift-users <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
I posted this on Apple’s developer forums, and someone suggested trying this here.
Basically, see https://forums.developer.apple.com/thread/80349

but in a nutshell: consider that a widely used class/struct (such as CGPoint) is missing some “obvious” functionality [don’t debate that part, just go with it for now], such as the ability to scale a point by a scalar using * as an operator: so in my awesome library “GeometryBase” I write

  public func * (left: CGPoint, right: double) -> CGPoint {
      return CGPoint(x: right*left.x, y: right*left.y)
  }

Why public? Well, of course, because I want to use library GeometryBase in many apps or other libraries, and now this overload exists in only one place.

But other bright people have the same idea, and now I want to use their libraries. (some of them in my company, some of them not.)

And now we’re stuck, because everyone is trying to make up for the same (perceived) lack and everyone wants them public so that they don’t have to keep sticking them in each library they write.

This is not a made up situation: many people even within one company trying to share code somewhat informally are going to write the same code to make using CGPoint/Size/Rect easier, and now we can’t share anything safely.

Anybody got some good ideas what to do about this?

[Same question could apply to adding extensions.]

_______________________________________________
swift-users mailing list
swift-users@swift.org <mailto:swift-users@swift.org>
https://lists.swift.org/mailman/listinfo/swift-users


(Howard Lovatt) #7

Jordon Rose from Apple said:

"It's tracked by SR-3908 <https://bugs.swift.org/browse/SR-3908>
. (The description's a little different but it's the same underlying
issue.)"

  -- Howard.

···

On 21 June 2017 at 12:07, David Baraff <davidbaraff@gmail.com> wrote:

On Jun 20, 2017, at 6:59 PM, Howard Lovatt <howard.lovatt@gmail.com> > wrote:

There is a *bug* that the Swift people know about, but you are **meant**
to be able to do this:

Is there a plan to fix this?
If it worked properly this would be quite wonderful.

ModuleA

A.swift

public protocol P {

func m() -> String

}

extension Int: P {

public func m() -> String { return "AP.m" }

}

ModuleB

B.swift

public protocol P {

func m() -> String

}
extension Int: P {

public func m() -> String { return "BP.m" }

}

ModuleC

A.swift

import ModuleA

func am(_ i: Int) -> String { return i.m() }

B.swift

import ModuleB

func bm(_ i: Int) -> String { return i.m() }

main.swift

let i = 0

print(am(i))
print(bm(i))

  -- Howard.

On 21 June 2017 at 00:02, David Baraff via swift-users < > swift-users@swift.org> wrote:

I posted this on Apple’s developer forums, and someone suggested trying
this here.
Basically, see https://forums.developer.apple.com/thread/80349

but in a nutshell: consider that a widely used class/struct (such as
CGPoint) is missing some “obvious” functionality [don’t debate that part,
just go with it for now], such as the ability to scale a point by a scalar
using * as an operator: so in my awesome library “GeometryBase” I write

  public func * (left: CGPoint, right: double) -> CGPoint {
      return CGPoint(x: right*left.x, y: right*left.y)
  }

Why public? Well, of course, because I want to use library GeometryBase
in many apps or other libraries, and now this overload exists in only one
place.

But other bright people have the same idea, and now I want to use their
libraries. (some of them in my company, some of them not.)

And now we’re stuck, because everyone is trying to make up for the same
(perceived) lack and everyone wants them public so that they don’t have to
keep sticking them in each library they write.

This is not a made up situation: many people even within one company
trying to share code somewhat informally are going to write the same code
to make using CGPoint/Size/Rect easier, and now we can’t share anything
safely.

Anybody got some good ideas what to do about this?

[Same question could apply to adding extensions.]

_______________________________________________
swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users