Named arguments

[Jacob Carlborg]

On 2017-10-24 22:36, H. S. Teoh wrote:
> On Tue, Oct 24, 2017 at 01:22:41PM -0600, Jonathan M Davis via Digitalmars-d wrote:
> [...]
>> Personally, I don't want them in D. If you have enough arguments that
>> it matters, then the function probably has too many parameters or too
>> many similar parameters.
> 
> If a function has too many parameters, or only a small subset of
> parameters need to be something other than some default value, or the
> set of parameters may change frequently, then my default approach is to
> abstract the parameters into a struct:
> 
> 	struct OutputArgs {
> 		string filename;
> 		int width = 300;
> 		int height = 300;
> 		string fontDir = "/usr/share/local/fonts/arial.ttf";
> 		int fontSize = 12;
> 		Color background = Color.black;
> 		Color foreground = Color.white;
> 		bool antiAlias = true;
> 	}
> 
> 	void generateOutput(OutputArgs args) { ... }
> 
> 	void main() {
> 		// Setup function arguments.
> 		// N.B.: only .filename needs to be explicitly set.
> 		OutputArgs args;
> 		args.filename = "/tmp/output.png";
> 
> 		// Call function with mostly default arguments.
> 		generateOutput(args);
> 	}

For this, it would be nice if static initialization [1] work without 
temporary variables. Then it would be pretty close to named parameters.

[1] https://dlang.org/spec/struct.html#static_struct_init

-- 
/Jacob Carlborg