At one point while traveling the web, I came across a great page which contrasted the clarity and terseness of different methods of doing a sequence of operations without having to make a bunch of throwaway variables, e.g., Var1, Var2, Var3. It tried list comprehensions, folds, maps, etc. For some reason, now matter what I google, I can't find it again. Anyone have any idea what I'm talking about? Or want to explore the topic anyway?
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A:
Your question doesn't make much sense.
List comprehensions, fold, and map aren't for avoiding variables (nor are they interchangeable), they're the right ways to process data depending on what you're trying to do.
Dustin
2010-02-15 05:53:55
I guess he is talking about comparing solutions like: 1) `X1 = f(x), X2 = g(X1), X = h(X2)` 2) `X = h(g(f(x)))` 3) `X = lists:foldl(fun(F,X) -> F(X) end, x, [f,g,h])`.
Zed
2010-02-15 15:58:48
A:
It is probably more of an art than a science. In a nutshell my advice is to lean away from using throw-aways as a general habit, but equally, do not be afraid of using them intelligently and sparingly where you feel appropriate or necessary.
When you are starting to learn then by all means use throw-away variables if it helps you break things down into understandable chunks. But try to break away from that sooner rather than later, as using throw-aways may at times make your code harder to maintain and modify. On the other hand, even when you are experienced you may sometimes find that it is worth using throwaways for the same reason : keep things readable and manageable for less experienced programmers. Purists may say that you should never use them, but I believe that when you consider the lifetime costs of software maintenance it is important to remember that readability is very important. Maybe this argument doesn't apply if you are lucky enough to work in an environment that only hires the best of the best, but for the rest of us that's simply not a reflection of the real world.
The bottom line : what is "right" depends on your skill level, the skill level of your peers, what you are doing, and the likely volatility, complexity, and lifetime of the code. Use your best judgement.
Tim
2010-02-16 04:02:02
A:
In response to the answer saying the question doesn't make sense, you would certainly think it made sense if you saw the article to which I'm referring. The point is to elegantly process a series of statements without redundant intermediate variables. Zed is right on target. I really wish I could find the original link because it was super detailed and went through 5 or 6 methods, some of which were referenced from the erlang mailing list, and weighed the pros and cons of each.
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A:
This is the article you were looking for:
http://erlanganswers.com/web/mcedemo/VersionedVariables.html
none
2010-04-03 14:57:23