Re: String not enumerable, what about IO? (was Re: Symbol < String in Ruby > 1.8)

> -----Original Message-----
> From: Sam Roberts [mailto:[e-mail]] 
> Sent: Monday, October 16, 2006 3:09 PM
> To: [e-mail]
> Subject: String not enumerable, what about IO? (was Re: 
> Symbol < String in Ruby > 1.8)
> 
> 
> On Tue, Oct 17, 2006 at 05:14:09AM +0900, James Edward Gray II wrote:
> > On Oct 16, 2006, at 3:06 PM, Rick DeNatale wrote:
> > 
> > >I'm curious as to why it's a good thing to make String 
> nonenumerable 
> > >and remove String#each instead of just aliasing lines to 
> each?  Are 
> > >there drawbacks which make it worthwhile breaking existing code?
> > 
> > Well, now that we're stepping into the M17N world it no 
> longer makes  
> > sense to work with Strings until we specify a unit for the 
> content.   
> > Each what?  Each character, line, or byte?
> > 
> > I really think this is a good move.  Every book that introduces
> > String#each says something like, "You probably don't expect 
> this, but  
> > Strings iterate over lines..."  Now it will always be crystal clear:
> > 
> >   my_str.chars.each { ... }
> 
> Does this break duck-typing of String, IO, and Array?
> 
> I have libraries that take an object that they expect to 
> respond to #each, yielding each line.  That object can be an 
> Array of strings, a String, an IO, or some other kind of 
> "source" object (useful to write a tiny object that filters 
> the lines before yielding them, maybe do utf-16 to utf-8 
> conversion, for example). I don't have to do any checking of 
> the class of the input object, I just document how it has to "quack":
> 
>   #each should yield each line of the input
> 
> I haven't looked at 1.9, does #each for IO still break at 
> each line? Or is IO also no longer enumerable, and you have to do:
> 
>   my_io.chars.each { ...} # used to be #each_byte
>   my_io.lines.each { ...} # used to be #each
> 
> ?
> 
> The same arguments about "unit of content" applies to IO, of 
> course, so I would expect this.
> 
> Even if IO does support #lines, I will have to either rewrite 
> my code to have a case based on the input object class, or 
> perhaps a responds_to? for #lines.
> 
> Sam
> 
> Btw, I'm assuming that #lines returns an Enumerable, not an 
> Array, because exploding a string into an Array of all its 
> constituent lines in-memory at once would be kindof heavy.

Oops, I realized right after posting that Sam is expressing the same
concerns that I have (and I forgot about IO!).

- Dan


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