I was browsing the net the other day, minding my own business, when I came across this:
http://giantrobots.thoughtbot.com/2007/5/1/coding-without-ifs
In summary, Jared Carroll is proposing to replace
def update_subscriptions
Subscription.find(:all).each do |each|
if each.expired?
each.renew!
else
each.update!
end
end
endwith
def update_subscriptions
subscriptions = Subscription.find :all
expired = subscriptions.select {|each| each.expired?}
expired.each {|each| each.renew!}
active = subscriptions.reject {|each| each.expired?}
active.each {|each| each.update!}
endin the name of avoiding conditionals in Ruby. You’ll notice that the second version loops through the ’subscriptions’ array 3 times rather than one. In the comments (which span 9 A4 pages) follows a lengthy discussion on the aesthetics and validity of the design of the second solution. It struck me then that Ruby gives you power, a lot of power - perhaps, sometimes, too much power.
I’m reading Paul Graham’s Hackers and Painters at the moment, and continue with his “hacking is like a visual art” analogy, I’d like to propose the following: Ruby is to Java (or C#) what photography is to oil painting. As with all analogies, it has its limitations, but the logic is as follows:
- creating an image using oil painting is long and hard
- creating an image using photography is quick and easy
- because creating an image is quicker with photography, the amount of time spent actually creating the image becomes a proportionally smaller part of the artistic process than it is with oil painting
- as a result, the percentage of time spent on ’secondary’ considerations (lenses, film types, darkroom exposure techniques, filters, etc.) becomes a proportionally larger part of the artistic process
Most of the professional photographers I know actually spend little time thinking about the secondary considerations such as lenses, film types etc. - they seem to find something they like and stick with it, reviewing their choices only occasionally. However, some get tempted into spending a lot of time and energy debating the relative merits of different lenses, film types, darkroom exposure techniques etc. These items are still only a minor factor of a good picture; the most important element in a good picture is unarguably its content (in a studio picture, this could be the subject, angle, background, lighting, pose etc.)
The similarity here, I think, is that Ruby has empowered programmers to think about the lenses, film types etc. a lot more because taking a picture has just become so much easier. There is not doubt in my mind, however, that whether to use conditional logic or closures is a minor consideration compared to the main (and hardest to attain) aim of the hacker, which is the beauty of the resulting solution; as tempting as it may be to debate the best polarizing filter, debates about language constructs are only as valuable as their contribution to achieving that aim is (which in this case would probably be minor).
P.S. I’m not at all arguing that Jared Carroll or any of the commenters in his blog are bad programmers (most of them are probably more experienced and talented than I am), or that debating about lenses and cameras is pointless - it isn’t, but spending more time thinking about them than actually taking pictures is counter-productive for a photographer. I’m just reminding myself how easy it it to get sidetracked.