add res.locals.use

[smagch]

This is a experimental implementation of feature request issue 1120 which I opened.

I still don't quite understand connect/express ecosystem. As I see in issure 1000 app.local is implemented by expando rather than prototype inheritance.

I don't know about javascript performance, but it seems to me that mixining to every response as I implemented is quite inefficient.

[smagch]

Ah, I didn't know pull request automatically opens a issue...

[tj]

nah it's not inefficient relative to anything else connect/express/your application is doing. The reason it is assign lazily like this is because it needs to "mixin" to itself since you can do res.locals({ obj: 'here' }). Even if we could change it to the prototype it would be a veryyyy small micro-optimization

[smagch]

Yeah, exactly. It would be very tiny since local.init() isn't doing heavy stuff. It seems api of locals is nice but it also causes a tiny shortcoming that it need to exposes "use" and "callbacks" field directly on local.

I'll add more test and comments when I have a time.

[tj]

I added it already :D dd33ef2

[smagch]

Ah, I missed that commit . Thanks.