try_ruby_400.md

lang	EN
title	All together now
answer	^4$
ok	Yes, Shakespeare wrote 4 plays in 1591
error	Answer for the year 1591 should be 4
load	prev

Now suppose we only want to know the names and number of plays written by Shakespeare in a certain year.

Ruby lets us select values from a hash. The select method uses a block to let us define what to select and returns what it found.

We can then use the results returned by select in the each method as before by simply adding it after the select block. This is another example of method chaining, which we saw earlier when reversing a poem.

I have prepared the count_plays method for you. See if you can find out how many plays were written by Shakespeare in the year 1591. Try this:

def count_plays(year)
  s = get_shakey
  
  s["William Shakespeare"]
    .select { |k, v|
      v["finished"] == year
    }.each { |key, val|
      puts val["title"]
    }.count
end

puts count_plays(1591)

Did you notice that I chained the count method at the end of the each method. This gives us a return value for the count_plays method.

There is another possibility for chaining here. See that lonely line s = get_shakey. You could add the ["William Shakespeare"].select { |k, v| at the end of get_shakey (no dot needed in this case).