Re: How do you cope with 2 or more optional parameters?

[Michal Kolodziejczyk <miko@...>]

On 18.12.2009 18:19, Javier Guerra wrote:
> On Fri, Dec 18, 2009 at 12:07 PM, spir <denis.spir@free.fr> wrote:
>> PS: There are certainly several techniques (eg thought at requiring a table for opt args). I'd like to review various possibilities.
> 
> roughly in order of personal preference:
> 
> - try to design the API so that it doesn't make sense to have more
> than 1 optional parameter

This is interesting... That would be kind of dataflow programming:

http://en.wikipedia.org/wiki/Dataflow_programming

Here is an example (but this assumes some form of object oriented
programming):

object={
  setX=function(self, value)
    self.X=value
    return self
  end,
  setY=function(self, value)
    self.Y=value
    return self
  end,
  setZ=function(self, value)
    self.Z=value
    return self
  end
}
setmetatable(object, {__tostring=function(self)
  return(string.format("X=%s Y=%s Z=%s", tostring(self.X),
tostring(self.Y), tostring(self.Z)))
  end
})

object:setX(1):setZ(3) -- instead of object:setXYZ(1,nil,3)
print(object)

Regards,
	miko