YesOrNo: useful idiom helper or wanking?

[FeepingCreature]

On 11.04.2011 16:53, Andrei Alexandrescu wrote:
> A fair amount of code in std uses this idiom:
> 
> enum SomeOption { no, yes }
> 
> void someFunction(...parms..., SomeOption, ...more_parms...) { ... }
> 
> SomeOption is really a Boolean but replaces the unhelpful call syntax
> someFunction(...args..., false, ...more_args...) with the
> self-documenting ...args..., SomeOption,no, ...more_args...).
> 
> The liabilities of using Booleans for describing flags have been
> documented in several places, including McConnell's Code Complete. I
> think the idiom above is a good replacement.
> 
> One issue I have with it is that it requires separate definition and
> documentation. Usually the documentation awkwardly states "This type is
> really an option for someFunction, which you haven't seen yet. Skip this
> for now, then get back, and you'll understand." Moving the enum to after
> the function is possible but equally confusing.
> 
> So I was thinking of planting a simple template in std.typecons:
> 
> template YesOrNo(string name)
> {
>     mixin("enum "~name~" : bool { no, yes }");
> }
> 
> That way, the definition of the function needs no separately-defined is
> self-documenting:
> 
> void someFunction(...parms..., YesOrNo!"SomeOption", ...) { ... }
> 
> The question is to what extent this would mark progress and fostering
> structured use of this idiom, versus just confusing beginners and adding
> deadweight to Phobos.
> 
> 
> 
> Andrei

Named parameters fix this without the need for workarounds.

someFunction(...parms..., someOption=>true, ...more parms....);