用Ruby以编程方式生成多行字符串

这是一种方法:

code = []
code << "next line of code #{something}"
code << "another line #{some_included_expression}"
code.join("\n")

如果要构建文本块,最简单的方法就是使用%运算符。例如:

code = %{First line
second line
Third line #{2 + 2}}

“代码”将是

"First line\n second line\n Third line 4"

使用<<-运算符:

code = <<-CODE
var1 = "foo"
var2 = "bar"
CODE

我想,你只要把……嵌入你的弦中就行了。以下是一个有趣的方法:

class String
  def / s
    self << s << "\n"
  end
end

然后

f = ""           # => ""
f / 'line one'   # => "line one\n"
f / 'line two'   # => "line one\nline two\n"
f / 'line three' # => "line one\nline two\nline three\n"

这将启用如下功能:

"" / "line 1" / "line 2" / "line 3" # => "line 1\nline 2\nline 3\n"

甚至:

f/
"line one"/
"line two"/
"line three"     # => "line one\nline two\nline three\n"

这里介绍了一种方法 here :

str = <<end.margin
  |This here-document has a "left margin"
  |at the vertical bar on each line.
  |
  |  We can do inset quotations,
  |  hanging indentions, and so on.
end

这是通过以下方式实现的:

class String
  def margin
    arr = self.split("\n")             # Split into lines
    arr.map! {|x| x.sub!(/\s*\|/,"")}  # Remove leading characters
    str = arr.join("\n")               # Rejoin into a single line
    self.replace(str)                  # Replace contents of string
  end
end

我想问题是:缺少可移植性/猴子补丁的存在是否会使这个解决方案变得糟糕?

怎么了:

code = "next line of code #{something}\n"+
       "another line #{some_included_expression}"

您可以将多行文本放在一个文件中,并使用erb来解析它(注意erb包含在ruby中)

require 'erb'

multi_line_string = File.open("multi_line_string.erb", 'r').read
template = ERB.new(multi_line_string)
template.result(binding)

(erb可以从绑定访问变量,这个对象提供对实例方法的访问,以及由另一个对象拥有的变量。通过将其设置为“绑定”,它指向自身)

文档 here .