Ruby运算符优先级 #

2 + 3 * 4
(2 + 3) * 4

10 - 4 / 2
(10 - 4) / 2

2 ** 3 ** 2
(2 ** 3) ** 2

true || false && false
(true || false) && false

!true && false
!(true && false)

1 < 2 && 3 < 4
(1 < 2) && (3 < 4)

1 < 2 || 3 > 4 && 5 < 6
1 < 2 || ((3 > 4) && (5 < 6))

a = true && false
a

a = true and false
a

b = false || true
b

b = false or true
b

a = true && false
a = true and false

a = false || true
a = false or true

if a && b
  do_something
end

save && redirect or render(:new)

result = operation or raise "失败"

a = false || true
a = false or true

a = nil || "default"
a = nil or "default"

name = params[:name] || "Default"

result = operation or return

!true && false
not true && false

!false || true
not false || true

if !valid?
  handle_error
end

unless valid?
  handle_error
end

return not authorized?

(1..5) === 3
1..5 === 3

if (1..5) === x
  puts "in range"
end

x = 3
(1..5) === x
1..5 === x

true ? 1 : 2
true && false ? 1 : 2
(true && false) ? 1 : 2

a = true ? 1 : 2
a = true ? 1 : 2 || 3

score = 85
result = score >= 90 ? "A" : score >= 80 ? "B" : "C"
result = score >= 90 ? "A" : (score >= 80 ? "B" : "C")

def double(x)
  x * 2
end

double 2 + 3
double(2 + 3)
double(2) + 3

"hello".upcase.length
"hello".upcase + " world"

10 - 5 - 3
(10 - 5) - 3

100 / 10 / 2
(100 / 10) / 2

2 ** 3 ** 2
2 ** (3 ** 2)

a = b = c = 1
a = (b = (c = 1))

a = b = 1
a = (b = 1)

a ||= b ||= 1
a ||= (b ||= 1)

if (user.admin? || user.moderator?) && post.published?
  allow_edit
end

result = (a + b) * (c - d)

a = b = c = []
a = (b = (c = []))

x = y || z && w
x = y || (z && w)
x = (y || z) && w

if (a && b) || (c && d)
  do_something
end

result = ((a + b) * c - d) / e

name = params[:name] || params[:nickname] || "Guest"

result = condition ? value1 : value2

value = a || b || c

if (1..10) === x && x.even?
  puts "偶数且在1-10之间"
end

if x > 0 && x < 100
  puts "0 < x < 100"
end

def can_access?(user, resource)
  (user.admin? || user.owner_of?(resource)) && resource.active?
end

def valid?(data)
  data && !data.empty? && data.size > 0
end

if user&.profile&.avatar&.url
  puts user&.profile&.avatar&.url
end

url = user&.profile&.avatar&.url || "default.png"

if (a && b) || (c && d)
  do_something
end

if a && b
  do_something
end

result = a || b

save && redirect or render(:new)

copy_file or raise "复制失败"

if (user.admin? || user.moderator?) && post.published? && !post.locked?
  allow_edit
end

def can_edit?
  (admin? || moderator?) && published? && !locked?
end

if can_edit?
  allow_edit
end