Although couldn't you make a case the other way around? Make the caller rather than the callee responsible for deciding whether or not it wants its variable mangled? Say you made the method responsible for not mangling. There's no real precedent for assuming that about rails methods in general, but if you did that and had outside code relying on that, what if you later changed the method to go ahead and mutate the parameter? Now you've still got outside, possibly dangerous dependencies.
Although I do get that by coding the protection in the callee, you only have to do it once. Maybe that's enough reason. -glenn On Tue, Jul 26, 2011 at 4:54 PM, Greg Willits <[email protected]> wrote: > On Jul 26, 2011, at 3:39 PM, Glenn Little wrote: > >> Just curious, is there a ruby best practice for effectively passing >> parameters by value to protect them from side effects? >> <snip> > >> def recurse(x = nil) >> y = x.dup >> y = <some processing to reflect current node> >> self.children.each do |c| >> c.recurse(y) >> end >> end > > > I do it as shown above. Make the method that would otherwise do the mangling, > responsible for NOT mangling it. IMO, putting the dup as part of the > parameters assumes unnecessary knowledge of how the method works. If you > change the method some day, or want the mangling, you potentially have a > bunch of code outside the method to change. Keep it encapsulated. > > -- gw > > > > -- > SD Ruby mailing list > [email protected] > http://groups.google.com/group/sdruby > -- SD Ruby mailing list [email protected] http://groups.google.com/group/sdruby
