这里有更多的方法:

"String1" + "String2"

"#{String1} #{String2}"

String1<<String2

等等……

情况很重要，例如:

# this will not work
output = ''

Users.all.each do |user|
  output + "#{user.email}\n"
end
# the output will be ''
puts output

# this will do the job
output = ''

Users.all.each do |user|
  output << "#{user.email}\n"
end
# will get the desired output
puts output

在第一个示例中，与+操作符连接将不会更新输出对象，然而，在第二个示例中，<<操作符将在每次迭代中更新输出对象。因此，对于上述类型的情况，<<更好。

这里有更多的方法:

"String1" + "String2"

"#{String1} #{String2}"

String1<<String2

等等……

如果只是连接路径，可以使用Ruby自己的File。连接方法。

source = File.join(ROOT_DIR, project, 'App.config')

从http://greyblake.com/blog/2012/09/02/ruby-perfomance-tricks/

使用<<即concat比+=更有效，因为后者创建了一个临时对象并用新对象覆盖第一个对象。

require 'benchmark'

N = 1000
BASIC_LENGTH = 10

5.times do |factor|
  length = BASIC_LENGTH * (10 ** factor)
  puts "_" * 60 + "\nLENGTH: #{length}"

  Benchmark.bm(10, '+= VS <<') do |x|
    concat_report = x.report("+=")  do
      str1 = ""
      str2 = "s" * length
      N.times { str1 += str2 }
    end

    modify_report = x.report("<<")  do
      str1 = "s"
      str2 = "s" * length
      N.times { str1 << str2 }
    end

    [concat_report / modify_report]
  end
end

输出:

____________________________________________________________
LENGTH: 10
                 user     system      total        real
+=           0.000000   0.000000   0.000000 (  0.004671)
<<           0.000000   0.000000   0.000000 (  0.000176)
+= VS <<          NaN        NaN        NaN ( 26.508796)
____________________________________________________________
LENGTH: 100
                 user     system      total        real
+=           0.020000   0.000000   0.020000 (  0.022995)
<<           0.000000   0.000000   0.000000 (  0.000226)
+= VS <<          Inf        NaN        NaN (101.845829)
____________________________________________________________
LENGTH: 1000
                 user     system      total        real
+=           0.270000   0.120000   0.390000 (  0.390888)
<<           0.000000   0.000000   0.000000 (  0.001730)
+= VS <<          Inf        Inf        NaN (225.920077)
____________________________________________________________
LENGTH: 10000
                 user     system      total        real
+=           3.660000   1.570000   5.230000 (  5.233861)
<<           0.000000   0.010000   0.010000 (  0.015099)
+= VS <<          Inf 157.000000        NaN (346.629692)
____________________________________________________________
LENGTH: 100000
                 user     system      total        real
+=          31.270000  16.990000  48.260000 ( 48.328511)
<<           0.050000   0.050000   0.100000 (  0.105993)
+= VS <<   625.400000 339.800000        NaN (455.961373)

木偶:

$username = 'lala'
notify { "Hello ${username.capitalize}":
    withpath => false,
}