# String interpolation method? **URL:** \ **Category:** ruby-talk\ **Created:** [27 February 2008 22:53 UTC](https://rubytalk.org/t/string-interpolation-method/44819 "2008-02-27T22:53:36Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![John\_Carter](https://avatars.discourse-cdn.com/v4/letter/j/2bfe46/32.png) [@John\_Carter](https://rubytalk.org/u/John_Carter)\ **Post date:** [27 February 2008 22:53 UTC](https://rubytalk.org/t/string-interpolation-method/44819/1 "2008-02-27T22:53:36Z")
Ok, I'm being stupid probably... But I can't spot a method to do string interpolation. I have a string... a = 'bra#{c}ket' The variable c isn't available at the stage of setting that up. Hence the use of '' instead of "". The variable will be available later.... At that stage I want to do something like... c=' see ' a.interpolate The closest I can get is a bit fugly... eval "\"#{a}\"" =\> "bra see ket" Any better way? Thanks, John Carter Phone : (64)(3) 358 6639 Tait Electronics Fax : (64)(3) 359 4632 PO Box 1645 Christchurch Email : [john.carter@tait.co.nz](mailto:john.carter@tait.co.nz) New Zealand ---
**Author:** ![Jari\_Williamsson](https://avatars.discourse-cdn.com/v4/letter/j/c4cdca/32.png) [@Jari\_Williamsson](https://rubytalk.org/u/Jari_Williamsson)\ **Post date:** [27 February 2008 23:06 UTC](https://rubytalk.org/t/string-interpolation-method/44819/2 "2008-02-27T23:06:50Z")
John Carter wrote: > Ok, I'm being stupid probably... > > But I can't spot a method to do string interpolation. > > I have a string... > > a = 'bra#{c}ket' > > The variable c isn't available at the stage of setting that up. Hence > the use of '' instead of "". > > The variable will be available later.... > > At that stage I want to do something like... > > c=' see ' > a.interpolate > > The closest I can get is a bit fugly... > > eval "\"#{a}\"" > =\> "bra see ket" > > Any better way? eval a Best regards, Jari Williamsson ---
**Author:** ![Mark\_Bush](https://avatars.discourse-cdn.com/v4/letter/m/e274bd/32.png) [@Mark\_Bush](https://rubytalk.org/u/Mark_Bush)\ **Post date:** [27 February 2008 23:24 UTC](https://rubytalk.org/t/string-interpolation-method/44819/3 "2008-02-27T23:24:03Z")
John Carter wrote: > eval "\"#{a}\"" > =\> "bra see ket" > > Any better way? Not better. Just different: eval '"%s"'%(a) Does the same thing but without needing the backslashes. I don't see any other way really. You must have a double eval in some manner. One to get the value of a and one to evaluate the result. The first eval can be explicit (as in your example with #{}) or implicit (as in my example). > **···** > > -- > Posted via [http://www.ruby-forum.com/\](http://www.ruby-forum.com/%5C). ---
**Author:** ![James\_Edward\_Gray\_II](https://avatars.discourse-cdn.com/v4/letter/j/ea5d25/32.png) [@James\_Edward\_Gray\_II](https://rubytalk.org/u/James_Edward_Gray_II)\ **Post date:** [27 February 2008 23:31 UTC](https://rubytalk.org/t/string-interpolation-method/44819/4 "2008-02-27T23:31:47Z")
You want a templating solution, like the ERb code that ships with Ruby:    #!/usr/bin/env ruby -wKU    require "erb"    template = ERB.new("bra\<%= c %\>ket")    # and later...    c = "c"    p template.result    \_\_END\_\_ Hope that helps. James Edward Gray II > **···** > > On Feb 27, 2008, at 4:53 PM, John Carter wrote: > > > Ok, I'm being stupid probably... > > > > But I can't spot a method to do string interpolation. > > > > I have a string... > > > > a = 'bra#{c}ket' > > > > The variable c isn't available at the stage of setting that up. ---
**Author:** ![yermej](https://avatars.discourse-cdn.com/v4/letter/y/b2d939/32.png) [@yermej](https://rubytalk.org/u/yermej)\ **Post date:** [27 February 2008 23:50 UTC](https://rubytalk.org/t/string-interpolation-method/44819/5 "2008-02-27T23:50:04Z")
I would do it thusly: a = "bra%sket" c = ' see ' a % c =\> "bra see ket" > **···** > > On Feb 27, 4:53 pm, John Carter \ wrote: > > > Ok, I'm being stupid probably... > > > > But I can't spot a method to do string interpolation. > > > > I have a string... > > > > a = 'bra#{c}ket' > > > > The variable c isn't available at the stage of setting that up. Hence > > the use of '' instead of "". > > > > The variable will be available later.... > > > > At that stage I want to do something like... > > > > c=' see ' > > a.interpolate > > > > The closest I can get is a bit fugly... > > > > eval "\"#{a}\"" > > =\> "bra see ket" > > > > Any better way? > > > > Thanks, > > > > John Carter Phone : (64)(3) 358 6639 > > Tait Electronics Fax : (64)(3) 359 4632 > > PO Box 1645 Christchurch Email : john.car...@tait.co.nz > > New Zealand ---
**Author:** ![7rans](https://avatars.discourse-cdn.com/v4/letter/7/a8b319/32.png) [@7rans](https://rubytalk.org/u/7rans)\ **Post date:** [28 February 2008 02:39 UTC](https://rubytalk.org/t/string-interpolation-method/44819/6 "2008-02-28T02:39:43Z")
=\> require 'facets/string/interpolate' =\> true > > a = 'bra#{c}ket' =\> "bra\#{c}ket" > > c = 4 =\> 4 > > String.interpolate{a} =\> "bra4ket" T. ---
**Author:** ![Jari\_Williamsson](https://avatars.discourse-cdn.com/v4/letter/j/c4cdca/32.png) [@Jari\_Williamsson](https://rubytalk.org/u/Jari_Williamsson)\ **Post date:** [27 February 2008 23:12 UTC](https://rubytalk.org/t/string-interpolation-method/44819/7 "2008-02-27T23:12:31Z")
Jari Williamsson wrote: > John Carter wrote: > > > Ok, I'm being stupid probably... > > > > But I can't spot a method to do string interpolation. > > > > I have a string... > > > > a = 'bra#{c}ket' > > > > The variable c isn't available at the stage of setting that up. Hence > > the use of '' instead of "". > > > > The variable will be available later.... > > > > At that stage I want to do something like... > > > > c=' see ' > > a.interpolate > > > > The closest I can get is a bit fugly... > > > > eval "\"#{a}\"" > > =\> "bra see ket" > > > > Any better way? > > eval a I spoke too soon - my suggestion will not work... Best regards, Jari Williamsson