this argument to lambda revisited

[Charles Lowell]

I think I've found a nice solution to the whole problem of how the `this` object is passed in a function. I've implemented it on the latest Racer beta, but wanted to share it with a larger audience.

Basically, each context has a instance of Access, which has methods through which every 

call(receiver, *args)

methodcall(receiver, *args)

These,  by default, delegate to `obj`, so the Access class looks like

class Access

  def methodcall(code, this, *args)

code.methodcall(this, *args)

  end

end

and then we have a module that gets included into Proc

module Access::Proc

  //ignore `this`

  def methodcall(this, *args)

    self.call(*args)

  end

end

class Proc

  include Access::Proc

end

This way, you can set behavior for Procs inside a JS::Context at every possible level. At the object level:

//accept `this` parameter when invoking a code block

module AcceptThis

  def methodcall(this, *args)

    call this, *args

  end

end

cxt = JS::Context.new

say = cxt['say'] = proc {|this, one, two| }

//accept `this` parameter, but only for this object

say.extend AcceptThis

//accept `this` parameter for all procs inside this context

context.access.extend(Module.new do

  def methodcall(code, this, *args)

    code.extend AcceptThis

    super

  end

end)

//accept `this` parameter globally for all procs in the process

class Proc

  include AcceptThis

end

It seems pretty clean and flexible.

cheers,

Charles

Charles Lowell 

thefrontside.net | twitter: @cowboyd | github: cowboyd

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