gistfile1.rb

# if ([a valueForKey:@"key"] == [NSNull null])
#   obj.foo = [a valueForKey:@"key"];

# Copied straight into ruby
if a["key"] != nil
  obj.foo = a["key"]
end

# Use a ruby method to test for nil
if !a["key"].nil?
  obj.foo = a["key"]
end

# "if !" == "unless"
unless a["key"].nil?
  obj.foo = a["key"]
end

# "unless obj.nil?" == "if obj" if obj isn't going to be false
if a["key"]
  obj.foo = a["key"]
end

# Why waste three lines when we can do it in one
obj.foo = a["key"] if a["key"]

# Or if we care about a["key"] being false too
obj.foo = a["key"] unless a["key"].nil?


# Ew.
unless a["one"].nil?
  obj.one = a["one"]
end
unless a["two"].nil?
  obj.one = a["two"]
end
unless a["three"].nil?
  obj.one = a["three"]
end
unless a["four"].nil?
  obj.one = a["four"]
end

# Better
obj.foo = a["one"] unless a["one"].nil?
obj.foo = a["two"] unless a["two"].nil?
obj.foo = a["three"] unless a["three"].nil?
obj.foo = a["four"] unless a["four"].nil?

# "Best" (metaprogramming, ruby - fuck yeah!)
# %w() == Array
%w(one two three four).each do |key|
  obj.foo = a[key] unless a[key].nil?
end

Can't fork your own gists, so it was a toss up between editing it and making your comment outdated, or creating a new one and linking to it. Meh :)

And ew! Setting instance variables is a baaaad idea on an object you have no idea of the contents of. It could do any number of things in the setter methods (this is object-orientated code, it's fairly likely) that you'd bypass. If the setter does even set an instance variable! send("#{k}=", v) calls the setter and is much better from that respect.

You totally can fork your own gists! cf. http://gist.github.com/579109

And yeah, like I said, it’s not what was intended by that particular bit of code; but I consider it far, far more attractive than send hackery.

Unfortunately, it’s fairly ugly either way, mostly because Ruby’s object system sucks. (Objects aren’t just associative arrays, and I can’t just set any slot I want to any value I want, whenever I want? Man, and I used to like that object system! ashamed)