相关疑难解决方法(0)

为什么最后一个语句(语句末尾的"if(tmp2 = foo)")失败？

def foo;5;end

# this one works
if (tmp = foo)
  puts tmp.to_s
end

# why this one fails
puts tmp2.to_s if (tmp2 = foo) #=> undefined local variable or method ‘tmp2’ for main:Object