ruby coding style added

Author: pritam1994

ruby.md

@@ -1 +1,123 @@
-# Ruby
+# Ruby
+
+## Syntax
+
+* Never use `for`, unless you know exactly why. You can use `each` instead of `for`.
+
+  ```ruby
+  arr = [1, 2, 3]
+
+  # bad
+  for element in arr do
+    puts element
+  end
+
+  # good
+  arr.each { |element| puts element }
+  ```
+
+* Never use `then` for multi-line `if/unless`
+  
+  ```ruby
+  # bad
+  if some_condition then
+    # do something
+  end
+
+  #good
+  if some_condition
+    # do something
+  end
+  ```
+
+* Use ternary operator (`?:`) over `if/then/else/end` constructs for single line conditions.
+
+  ```ruby
+  # bad
+  result = if some_condition then something else something_else end
+
+  # good
+  result = some_condition ? something : something_else
+  ```
+
+* Always use `&&` and `||` instead of `and` and `or` keywords.
+
+* Avoid multi-line `?:`(ternary operator), use `if/unless` instead.
+
+* For single `if/unless` bolck write it in a single line.
+
+  ```ruby
+  # bad
+  if some_condition
+    do_something
+  end
+
+  # good
+  do_something if some_condition
+  ```
+
+* Never use `unless` with `else`. Write it inside `if-else` block
+  
+  ```ruby 
+  # bad
+  unless success?
+    puts "failure"
+  else
+    puts "success"
+  end
+
+  # good
+  if success?
+    puts "success"
+  else
+    puts "failure"
+  end
+  ```
+
+* Do not use parentheses around the condition of an `if/unless/while`.
+
+  ```ruby
+  # bad
+  if (x > 5)
+    # do something
+  end
+  
+  # good
+  if x > 5
+    # do something
+  end
+  ```
+
+* Avoid `return` where not required.
+ 
+  ```ruby
+  # bad
+  def some_method(arr)
+    return arr.size
+  end
+    
+  # good
+  def some_method(arr)
+    arr.size
+  end
+  ```
+
+* use `%w` freely.
+
+  ```ruby
+  # bad
+  arr = ["one", "two", "three"]
+  
+  # good
+  arr = %w(one two three)
+  ```
+
+## Naming
+
+* use `snake_case` for methods and variables.
+
+* use `CamelCase` for classes and modules.
+
+* Constants are written in all uppercase with underscores to separate words. like: `A_CONST`
+
+