Ruby: Variables defined in If/else statement are accessible outside of if/else? [duplicate]

Question

def foo   #bar = nil   if true     bar = 1   else     bar = 2   end   bar #<-- shouldn't this refer to nil since the bar from the if statement is removed from the stack? end  puts foo # prints "1" 

I always thought you had to make a temporary variable and define it as nil or an initial value so that variables defined inside an if/else statement would persist outside the scope of the if/else statement and not disappear off the stack?? Why does it print 1 and not nil?

Answer 1

Variables are local to a function, class or module defintion, a proc, a block.

In ruby if is an expression and the branches don't have their own scope.

Also note that whenever the parser sees a variable assignment, it will create a variable in the scope, even if that code path isn't executed:

def test   if false     a = 1   end   puts a end  test # ok, it's nil. 

It's bit similar to JavaScript, though it doesn't hoist the variable to the top of the scope:

def test   puts a   a = 1 end  test # NameError: undefined local variable or method `a' for ... 

So even if what you were saying were true, it still wouldn't be nil.