Intro to Scope
Intro to Scope
Warmup
What will the following code snippet output?
def print_vars(x, y)
x = 12
puts "x: " + x.to_s
puts "y: " + y.to_s
end
x = 1
y = 5
print_vars(x, y)
print_vars(y, x)
x = 14
print_vars(x, y)
while x < 16
puts x + y
x += 1
end
puts x
Global Scope
# global_scope.rb
x = 10
puts "x is #{x}"
x += 20
puts "x is #{x}"
Global Scope (continued)
# global_scope.rb
x = 10
puts "x is #{x}"
x += 20
puts "x is #{x}"
def print_doubled_value(x)
puts "double the value #{x} is #{x * 2}"
end
print_doubled_value(x)
y = 27
print_doubled_value(y)
Global Scope (continued)
# global_scope.rb
def print_doubled_value(x)
orig = x
x = x * 2
puts "double the value #{orig} is #{x}"
puts "inner x is now: #{x}"
end
print_doubled_value(x)
puts "outer x is still: #{x}"
Global Scope (continued)
a = 4
b = 12
def combine_variables(x)
puts "inner x is: #{x}"
puts "and outer b is: #{b}"
end
combine_variables(a)
Blocks
ingredients = ["flour", "water", "yeast", "salt"]
method = "measure"
def unit
["teaspoon", "cup", "pinch"].sample
end
ingredients.each do |ingredient|
puts "#{method} one #{unit} #{ingredient}"
end
Blocks with Overlapping Inner/Outer Variables
new_ingredients = ["banana", "chocolate chips"]
temperature = 375
method = "bake"
new_ingredients.each do |ingredient|
method = "mix"
puts "#{method} the #{ingredient} at #{temperature} degrees"
end
puts method
Summary
- Define scope in your own words
- What are some of the benefits of scope?
- What will the following code snippet output?
def doubler(x)
doubled = x * y
puts doubled
end
def y
2
end
x = 4
doubler(x)
