Re: [swift-evolution] Proposal: Automatic initializer generation

2016-05-23 Thread L. Mihalkovic via swift-evolution 

> On May 23, 2016, at 7:24 PM, Matthew Johnson via swift-evolution 
>  wrote:
> 
> 
>> On May 23, 2016, at 10:52 AM, Kevin Nattinger via swift-evolution 
>>  wrote:
>> 
>> Discussed last month 
>> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160411/014890.html
>> And (linked from that thread) last year 
>> http://article.gmane.org/gmane.comp.lang.swift.evolution/727
>> 
>> I think it’s a good idea, but discussion seems to have just petered out 
>> without a formal proposal both times. 

IMHO the proposals were on a collision course with yet untouched parts of the 
language. 

> 
> This didn’t peter out.  My opinion on this topic evolved throughout the 
> review.  The perspective I came to is that the best approach may require 
> changes that are outside the scope of Swift 3.  I expect this to come up 
> again during the Swift 4 conversation.
> 
>> 
>> How about we just apply the struct auto-init behavior to classes? It’s nice 
>> and simple, and already in the language.
>> 
>>> On May 23, 2016, at 7:29 AM, Charlie Monroe via swift-evolution 
>>>  wrote:
>>> 
>>> A lot of initializers tediously assign values to variables which results in 
>>> a lot of code such as self.variable = arg1 (or even worse variable = 
>>> variable), mostly for classes that are meant to just encapsulate several 
>>> values.
>>> 
>>> I propose adding auto keyword (to be discussed - anyone has a better name 
>>> in mind?), which would automatically assign same-named variables. Example:
>>> 
>>> class User {
>>>var name: String
>>>var password: String
>>>
>>>init(auto name: String, auto password: String) {
>>>// No assignment required, the variables will be automatically 
>>> assigned.
>>>// Perform additional init stuff here.
>>>}
>>> }
>>> 
>>> This would, of course, work only if the argument has the same name as a 
>>> stored variable on the class.
>>> 
>>> Additionally, if the class is root, or the superclass has an initializer 
>>> that takes no arguments, I propose adding @auto_init annotation, which 
>>> would generate a default initializer, similar to what is done for structs:
>>> 
>>> @auto_init
>>> class User {
>>>var name: String
>>>var password: String
>>> }
>>> 
>>> Normally, such class would be illegal since it would have no accessible 
>>> initializers. The annotation could specify the access control as well: 
>>> @auto_init(private), @auto_init(internal), @auto_init(public).
>>> 
>>> If the class isn't root, but inherits from an object that has an 
>>> initializer that takes no arguments (e.g. NSObject), this would be allowed 
>>> as well and the initializer with no arguments would be called on super.
>>> 
>>> Any thoughts on this? Sorry, if this has been already discussed.
>>> 
>>> Charlie
>>> 
>>> ___
>>> swift-evolution mailing list
>>> swift-evolution@swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>> 
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Re: [swift-evolution] Proposal: Automatic initializer generation

2016-05-23 Thread Matthew Johnson via swift-evolution 

> On May 23, 2016, at 10:52 AM, Kevin Nattinger via swift-evolution 
>  wrote:
> 
> Discussed last month 
> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160411/014890.html
> And (linked from that thread) last year 
> http://article.gmane.org/gmane.comp.lang.swift.evolution/727
> 
> I think it’s a good idea, but discussion seems to have just petered out 
> without a formal proposal both times. 

This didn’t peter out.  My opinion on this topic evolved throughout the review. 
 The perspective I came to is that the best approach may require changes that 
are outside the scope of Swift 3.  I expect this to come up again during the 
Swift 4 conversation.

> 
> How about we just apply the struct auto-init behavior to classes? It’s nice 
> and simple, and already in the language.
> 
>> On May 23, 2016, at 7:29 AM, Charlie Monroe via swift-evolution 
>>  wrote:
>> 
>> A lot of initializers tediously assign values to variables which results in 
>> a lot of code such as self.variable = arg1 (or even worse variable = 
>> variable), mostly for classes that are meant to just encapsulate several 
>> values.
>> 
>> I propose adding auto keyword (to be discussed - anyone has a better name in 
>> mind?), which would automatically assign same-named variables. Example:
>> 
>> class User {
>>  var name: String
>>  var password: String
>>  
>>  init(auto name: String, auto password: String) {
>>  // No assignment required, the variables will be automatically 
>> assigned.
>>  // Perform additional init stuff here.
>>  }
>> }
>> 
>> This would, of course, work only if the argument has the same name as a 
>> stored variable on the class.
>> 
>> Additionally, if the class is root, or the superclass has an initializer 
>> that takes no arguments, I propose adding @auto_init annotation, which would 
>> generate a default initializer, similar to what is done for structs:
>> 
>> @auto_init
>> class User {
>>  var name: String
>>  var password: String
>> }
>> 
>> Normally, such class would be illegal since it would have no accessible 
>> initializers. The annotation could specify the access control as well: 
>> @auto_init(private), @auto_init(internal), @auto_init(public).
>> 
>> If the class isn't root, but inherits from an object that has an initializer 
>> that takes no arguments (e.g. NSObject), this would be allowed as well and 
>> the initializer with no arguments would be called on super.
>> 
>> Any thoughts on this? Sorry, if this has been already discussed.
>> 
>> Charlie
>> 
>> ___
>> swift-evolution mailing list
>> swift-evolution@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
> 
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Re: [swift-evolution] Proposal: Automatic initializer generation

2016-05-23 Thread Charlie Monroe via swift-evolution 
Thanks for the links.

You can't apply auto-init behavior to all classes since it gets a bit more 
complicated once the only initializers available take some arguments - the 
compiler can't know what to pass where to super, so it would need to chain the 
arguments, which would lead to initializers with dozens of arguments. So in 
such case the auto-init is IMHO out of question.

The variant that I'm suggesting is simplified and restricted only to classes 
that either do not inherit from anything, or have an initializer that takes no 
arguments - which makes the issue much simpler than previously suggested.

I dislike the syntax of the previous proposal

init (self.a: Int, self.b: String) {
   //...
}

where you specify self.a: Int - IMHO this should be done using a keyword that 
automates it and I'd allow it only for arguments that match a variable on the 
instance. Or perhaps allowing something like auto(xyz) to specify the variable? 
Or #auto(xyz)?

This seems a bit more readable to me:

init (auto a: Int, auto b: String) {
   //...
}

If there is still some interest in making this a proposal, I can write it up.

Charlie


> On May 23, 2016, at 5:52 PM, Kevin Nattinger  wrote:
> 
> Discussed last month 
> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160411/014890.html
> And (linked from that thread) last year 
> http://article.gmane.org/gmane.comp.lang.swift.evolution/727
> 
> I think it’s a good idea, but discussion seems to have just petered out 
> without a formal proposal both times. 
> 
> How about we just apply the struct auto-init behavior to classes? It’s nice 
> and simple, and already in the language.
> 
>> On May 23, 2016, at 7:29 AM, Charlie Monroe via swift-evolution 
>>  wrote:
>> 
>> A lot of initializers tediously assign values to variables which results in 
>> a lot of code such as self.variable = arg1 (or even worse variable = 
>> variable), mostly for classes that are meant to just encapsulate several 
>> values.
>> 
>> I propose adding auto keyword (to be discussed - anyone has a better name in 
>> mind?), which would automatically assign same-named variables. Example:
>> 
>> class User {
>>  var name: String
>>  var password: String
>>  
>>  init(auto name: String, auto password: String) {
>>  // No assignment required, the variables will be automatically 
>> assigned.
>>  // Perform additional init stuff here.
>>  }
>> }
>> 
>> This would, of course, work only if the argument has the same name as a 
>> stored variable on the class.
>> 
>> Additionally, if the class is root, or the superclass has an initializer 
>> that takes no arguments, I propose adding @auto_init annotation, which would 
>> generate a default initializer, similar to what is done for structs:
>> 
>> @auto_init
>> class User {
>>  var name: String
>>  var password: String
>> }
>> 
>> Normally, such class would be illegal since it would have no accessible 
>> initializers. The annotation could specify the access control as well: 
>> @auto_init(private), @auto_init(internal), @auto_init(public).
>> 
>> If the class isn't root, but inherits from an object that has an initializer 
>> that takes no arguments (e.g. NSObject), this would be allowed as well and 
>> the initializer with no arguments would be called on super.
>> 
>> Any thoughts on this? Sorry, if this has been already discussed.
>> 
>> Charlie
>> 
>> ___
>> swift-evolution mailing list
>> swift-evolution@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
> 

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Re: [swift-evolution] Proposal: Automatic initializer generation

2016-05-23 Thread Kevin Nattinger via swift-evolution 
Discussed last month 
https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20160411/014890.html
And (linked from that thread) last year 
http://article.gmane.org/gmane.comp.lang.swift.evolution/727

I think it’s a good idea, but discussion seems to have just petered out without 
a formal proposal both times. 

How about we just apply the struct auto-init behavior to classes? It’s nice and 
simple, and already in the language.

> On May 23, 2016, at 7:29 AM, Charlie Monroe via swift-evolution 
>  wrote:
> 
> A lot of initializers tediously assign values to variables which results in a 
> lot of code such as self.variable = arg1 (or even worse variable = variable), 
> mostly for classes that are meant to just encapsulate several values.
> 
> I propose adding auto keyword (to be discussed - anyone has a better name in 
> mind?), which would automatically assign same-named variables. Example:
> 
> class User {
>   var name: String
>   var password: String
>   
>   init(auto name: String, auto password: String) {
>   // No assignment required, the variables will be automatically 
> assigned.
>   // Perform additional init stuff here.
>   }
> }
> 
> This would, of course, work only if the argument has the same name as a 
> stored variable on the class.
> 
> Additionally, if the class is root, or the superclass has an initializer that 
> takes no arguments, I propose adding @auto_init annotation, which would 
> generate a default initializer, similar to what is done for structs:
> 
> @auto_init
> class User {
>   var name: String
>   var password: String
> }
> 
> Normally, such class would be illegal since it would have no accessible 
> initializers. The annotation could specify the access control as well: 
> @auto_init(private), @auto_init(internal), @auto_init(public).
> 
> If the class isn't root, but inherits from an object that has an initializer 
> that takes no arguments (e.g. NSObject), this would be allowed as well and 
> the initializer with no arguments would be called on super.
> 
> Any thoughts on this? Sorry, if this has been already discussed.
> 
> Charlie
> 
> ___
> swift-evolution mailing list
> swift-evolution@swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

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[swift-evolution] Proposal: Automatic initializer generation

2016-05-23 Thread Charlie Monroe via swift-evolution 
A lot of initializers tediously assign values to variables which results in a 
lot of code such as self.variable = arg1 (or even worse variable = variable), 
mostly for classes that are meant to just encapsulate several values.

I propose adding auto keyword (to be discussed - anyone has a better name in 
mind?), which would automatically assign same-named variables. Example:

class User {
var name: String
var password: String

init(auto name: String, auto password: String) {
// No assignment required, the variables will be automatically 
assigned.
// Perform additional init stuff here.
}
}

This would, of course, work only if the argument has the same name as a stored 
variable on the class.

Additionally, if the class is root, or the superclass has an initializer that 
takes no arguments, I propose adding @auto_init annotation, which would 
generate a default initializer, similar to what is done for structs:

@auto_init
class User {
var name: String
var password: String
}

Normally, such class would be illegal since it would have no accessible 
initializers. The annotation could specify the access control as well: 
@auto_init(private), @auto_init(internal), @auto_init(public).

If the class isn't root, but inherits from an object that has an initializer 
that takes no arguments (e.g. NSObject), this would be allowed as well and the 
initializer with no arguments would be called on super.

Any thoughts on this? Sorry, if this has been already discussed.

Charlie

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