On 2010-11-15, at 4:50 PM, Ryan Davis wrote: > > On Nov 14, 2010, at 18:37 , Mark Rada wrote: > >> Now, when I try this out in macirb: (Case #3) >> >> require 'uri' >> test = URI.parse url unless (url = 'http://macruby.org/').nil? # error >> test = URI.parse url unless (url = 'http://wikipedia.org/').nil? # works >> >> If it doesn't work in the second case, why does it start working in the >> third case? > > First off, I hate this style of coding. If you didn't assign in a conditional > you'd avoid all of this crap to begin with. Assigning in conditionals is just > a sloppy and error prone way of coding and you should avoid it. This has been > a known anti-pattern in any algol-esque language since at least the 80s. > > That said... This actually has nothing to do with macruby and is an effect of > the ruby parser. It is about variable visibility.
Ah, that is what I was not understanding. Thanks for explaining. > > In case 3: > > + The first line has "URI.parse url" followed by "unless (url = ...).nil?" > + The first 'url' is actually parsed as a method call because the word has > never been seen before and wasn't added to the variable table. The second url > DOES add url to the variable table. > + The second line has the same thing, but by now, "url" has been added to the > variable table. This lets everything be parsed as a variable at parse time. _______________________________________________ MacRuby-devel mailing list MacRuby-devel@lists.macosforge.org http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel
