arrays - 具有特定格式的数组到字符串

Question

我有这样的哈希:

@password_constraints = {
  length: 'Must be at least 6 character long.',
  contain: [
      'one number',
      'one lowercase letter',
      'one uppercase letter.'
  ]
}

我想写一个方法来返回一个人类可读的字符串，这个字符串是从这个散列构建的，就像这样:

Must be at least 6 character long. Must contain: one number, one lowercase letter and an uppercase letter.

目前，我有一个非常冗长的方法，它有一个 each 遍历 @password_constraints[:contain] 数组，并且有几个条件来检查我是否必须把一个 ,，或者一个 and 或者什么都没有。

但我想要与 join(', ') 几乎相同的行为，但最后的分隔符必须是 and。

我正在寻找类似这种带有特殊join 的解决方案:

def password_constraints
  @password_constraints[:length] << ' Must contain.' << @password_constraints[:contain].join(', ') 
end

有没有办法让它更紧凑或更像 Ruby？

Answer 1

您可以使用 splat 运算符拆分数组，如果只有一个字符串，则只检查大小写:

def message(constraints)
  *others, second_last, last = constraints[:contain]
  second_last += " and #{last}" unless last.nil?
  "#{constraints[:length]} Must contain: #{(others << second_last).join(', ')}"
end

@password_constraints = {
  length: 'Must be at least 6 character long.',
  contain: [
      'one number',
      'one lowercase letter',
      'one uppercase letter.'
  ]
}

message(@password_constraints)
# => "Must be at least 6 character long. Must contain: one number, one lowercase letter and one uppercase letter." 

# if @password_constraints[:contain] = ['one lowercase letter', 'one uppercase letter.']
message(@password_constraints)
# => "Must be at least 6 character long. Must contain: one lowercase letter and one uppercase letter." 

# if @password_constraints[:contain] = ['one lowercase letter']
message(@password_constraints)
# => "Must be at least 6 character long. Must contain: one lowercase letter"