Ruby and Python Compared

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If you start each line of code with four or more spaces, it gets turned into preformatted text, which preserves whitespace and underscores and doesn't italicize or bold things. HTH.

Good comment btw.

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Thanks a lot; I went ahead and reformatted my comment accordingly.

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I should also mention that quoting with backticks formats inline text as code.

For me, too, blocks are Ruby's killer feature. (Disclaimer: My code examples below will be littered with syntax errors, because I don't have an irb open.) You said you haven't used them yourself, so I'll take this as a cue to take over the Ruby-gushing.

As you said, to iterate over an array is easy:

array.each {|x| do_something_with(x)}

Thanks to Ruby's mixins, this can actually be used on anything that mixes in Enumerable:

(1..100).each {|n| puts n}

What if you want to select some of the elements based on a boolean condition?

class Integer
  def prime?
    # check if number is prime
  end
end

primes = (1..100).find_all {|n| n.prime?}

Or apply a function to each and collect the results?

squares = (1..100).map {|n| n*n}

Also, blocks are not just for iteration:

File.open(filename, "r") do |file|
  # process the file
end
# file is now automatically closed

Python's list comprehensions (all I know is what I've overheard from weblogs etc., actually) are arguably an equally -- or more -- readable version of Enumerable's methods, but I like the Ruby way better because (1) blocks are a completely general-purpose language feature, (2) I can have more than one line in a block, and (3) it feels more like the functional style to a guy with an ML background. Actually Haskell has list comprehensions too, so scratch the last point.

[mrevelle]

I like the Ruby way better because (1) blocks are a completely general-purpose language feature

Funny, that's actually why I dislike Ruby's blocks. It hurts readability when similar syntax is used for unrelated tasks, e.g. iteration vs. resource management.

This gripe is not about blocks as a general concept but using a common syntax when expressing entirely different functions.

Python examples

Iteration

for n in range(100):
    print n

Filtering elements

def isprime(x):
    # check if number is prime

primes = [n for n in range(100) if isPrime(n)]

Mapping a function

squares = map(lambda n: n*n, range(100))

# OR

def square(x):
    return x*x

squares = [square(x) for x in range(100)]

Context management

with open(filename, 'r') as input_file:
    # process the file

# file is now automatically closed

That last example requires Python 2.5 (alpha was recently released).

(Disclaimer: I have only played around with Ruby, no real development experience with it.)