[swift-evolution] [Idea] Extending syntax for `extension`

[Braeden Profile]

No special restriction here.  Like I said, it’s just another way of writing a file-level extension within that namespace.  All the functions can then be defined as private, public, internal, etc. as necessary.  The point would be to define functionality for something within the right block.  If I’m writing an entire set of types within MathEvaluator (or SelectMode, or whatever I’m writing), I want to be able to keep the whole file within MathEvaluator’s scope.  I do, however, wish to write the subtypes in terms of “definition here, functionality there” the way extensions allow.

I don’t remember a verdict from the `struct MathEvaluator.Number` syntax discussion.  Was that shot down, or still a possibility?

> On Dec 5, 2016, at 3:04 PM, Saagar Jha <saagar at saagarjha.com> wrote:
> 
> How exactly would this work? Would it restrict the extension to only the scope it’s defined in?
> 
> Saagar Jha
> 
> 
> 
>> On Dec 5, 2016, at 1:48 PM, Braeden Profile via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> I really enjoy having the ability to write and nesting my code at the appropriate indentation level in my file.  Extensions are fabulous, but I wonder—solely for readability/style sake, could we allow you to properly namespace your extensions?  Though I don’t know the implementation cost of this, I think it could be useful to be able to write this:
>> 
>> class MathEvaluator
>> {
>> 	struct Number
>> 	{
>> 		let value: Double
>> 	}
>> 	
>> 	struct Operation
>> 	{
>> 		let numbers: (Number, Number)
>> 		let transform: (Double, Double) -> Double
>> 	}
>> 	
>> 	extension Number
>> 	{
>> 		var factors: [Double]
>> 		{
>> 			// Calculate and return the factors
>> 		}
>> 	}
>> }
>> 
>> …which would be completely equivalent to:
>> 
>> class MathEvaluator
>> {
>> 	struct Number
>> 	{
>> 		let value: Double
>> 	}
>> 	
>> 	struct Operation
>> 	{
>> 		let numbers: (Number, Number)
>> 		let transform: (Double, Double) -> Double
>> 	}
>> }
>> 	
>> extension MathEvaluator.Number
>> {
>> 	var factors: [Double]
>> 	{
>> 		// Calculate and return the factors
>> 	}
>> }
>> 
>> This change is in the same ball park as this, proposed a week or two ago:
>> 
>> struct MathEvaluator.Number
>> {
>> 	let value: Double
>> 	
>> 	var factors: [Double]
>> 	{
>> 		// Calculate and return the factors
>> 	}
>> }
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> 

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