Week 2 Day 1: Hashing Out Enumerable Methods

Major activities of the day: Homework review.  We seem to be moving a bit slowly because we're dealing with very fundamental programming tasks.  So we're focusing a lot on how to deal with hashes and arrays and manipulate them in ways that give us the information we need.

On the bright side, we had some time to go over the homework with other students and compare our algorithms, and we exchanged ideas that we had picked up while doing the homework.

One interesting thing I learned from another student was the .tap method, which can be used on all Ruby Objects.  Here's an example of how to use it:

def return_an_array_of_perfect_squares_up_to_25

  [].tap do |squares|

    i = 1

    while i**2 <= 25 

      squares << i**2

      i += 1

    end

  end

end

HUH???  What's the return value?  It turns out that .tap creates a placeholder, feeds that into a block, and returns the placeholder.  So it's the same as this:

def return_an_array_of_perfect_squares_up_to_25

  squares = []

  i = 1

  while i**2 <= 25 

    squares << i**2

    i += 1

  end

  squares

end

Possibly a bit more confusing, which is why I'm hesitant to use it in my own code, but it is a bit more concise, which is nice.  And it gives an excuse to indent!

NOTE: Example provided for illustration purposes only.  If I were programming this for real, this is how I would do it:

def return_an_array_of_perfect_squares_up_to_25

  (1..Math.sqrt(25)).map{|num| num**2}

end

And of course, that's the power of map/collect and select!    ＼（＾○＾）／


Skills developed: Extracting data from Arrays/Hashes, iterating over Arrays/Hashes


QOTD: "When you don’t create things, you become defined by your tastes rather than ability. Your tastes only narrow and exclude people. So create." - why the lucky stiff, author of why's (poignant) guide to ruby