Merge remote-tracking branch 'upstream/master' into master

1 files changed, 36 insertions, 1 deletions

diff --git a/ruby.html.markdown b/ruby.html.markdown
index 2595d1d5..4b96b71c 100644
--- a/ruby.html.markdown
+++ b/ruby.html.markdown
@@ -23,6 +23,15 @@ contributors:
 ```ruby
 # This is a comment
 
+=begin
+This is a multi-line comment.
+The beginning line must start with "=begin"
+and the ending line must start with "=end".
+
+You can do this, or start each line in
+a multi-line comment with the # character.
+=end
+
 # In Ruby, (almost) everything is an object.
 # This includes numbers...
 3.class #=> Integer
@@ -172,6 +181,9 @@ array = [1, 2, 3, 4, 5] #=> [1, 2, 3, 4, 5]
 # Arrays can contain different types of items.
 [1, 'hello', false] #=> [1, "hello", false]
 
+# You might prefer %w instead of quotes
+%w[foo bar baz] #=> ["foo", "bar", "baz"]
+
 # Arrays can be indexed.
 # From the front...
 array[0] #=> 1
@@ -247,6 +259,14 @@ else
   'else, also optional'
 end
 
+# If a condition controls invocation of a single statement rather than a block of code
+# you can use postfix-if notation
+warnings = ['Patronimic is missing', 'Address too short']
+puts("Some warnings occurred:\n" + warnings.join("\n"))  if !warnings.empty?
+
+# Rephrase condition if `unless` sounds better than `if`
+puts("Some warnings occurred:\n" + warnings.join("\n"))  unless warnings.empty?
+
 # Loops
 # In Ruby, traditional `for` loops aren't very common. Instead, these 
 # basic loops are implemented using enumerable, which hinges on `each`.
@@ -307,6 +327,11 @@ puts doubled
 puts array
 #=> [1,2,3,4,5]
 
+# another useful syntax is .map(&:method)
+a = ["FOO", "BAR", "BAZ"]
+a.map { |s| s.downcase } #=> ["foo", "bar", "baz"]
+a.map(&:downcase) #=> ["foo", "bar", "baz"]
+
 # Case construct
 grade = 'B'
 
@@ -402,7 +427,7 @@ def guests(&block)
 end
 
 # The 'call' method on the Proc is similar to calling 'yield' when a block is 
-# present. The arguments passed to 'call' will be forwarded to the block as arugments.
+# present. The arguments passed to 'call' will be forwarded to the block as arguments.
 
 guests { |n| "You have #{n} guests." }
 # => "You have 4 guests."
@@ -413,6 +438,16 @@ def guests(*array)
   array.each { |guest| puts guest }
 end
 
+# There is also the shorthand block syntax. It's most useful when you need
+# to call a simple method on all array items.
+upcased = ['Watch', 'these', 'words', 'get', 'upcased'].map(&:upcase)
+puts upcased
+#=> ["WATCH", "THESE", "WORDS", "GET", "UPCASED"]
+ 
+sum = [1, 2, 3, 4, 5].reduce(&:+)
+puts sum
+#=> 15
+
 # Destructuring
 
 # Ruby will automatically destructure arrays on assignment to multiple variables.