How to run a series of checks?

I'm trying to run a series of if/else statements but right now they basically end up being deeply nested if/else statements.

I'm ultimately wanting to say: If A isn't true, run B. If B isn't true, run C. If C isn't true, run D, and so on.

Crude example:

开发者_StackOverflow中文版

if a == b
  return true
else
  c = d/e
  if c = a
    return true
  else
    g = h*i

    if g == true
      return true
    else
      return false
    end
  end
end

---

Firstly, you don't need else when you're returning from the first branch of an if, so your

if (condition)
  return true
else
  # otherwise code
end

should always be written

if (condition)
  return true

# otherwise code

This can be written more succinctly in Rails:

return true if (condition)

# otherwise code

Secondly, this pattern is particularly hideous:

if (condition)
  return true
else
  return false
end

You should always prefer to simply return the condition, which is exactly equivalent (assuming the condition evaluates to boolean true/false):

return (condition)

Put these together and you get this drastically simplified, un-nested but identical code:

return true if a == b

c = d/e

return true if c == a

g = h*i

return g == true

---

return true if a == b
c = d/e
return true if c == a
g = h*i
return true if g == true
return false

You can use statement modifiers in Ruby to add conditional logic. So, instead of nested if statements, you can just do what you plan to do if some condition is met.

---

From your example, since you return when success is detected, there is no reason to nest the if statements. The following:

return true if a == b
c = d/e
return true if c == a
g = h*i
return g

would do exactly the same as your example. (Actually, I don' think my final return statement is required either)