# ''Macro'' operator **URL:** \ **Category:** Ruby\ **Created:** [August 28, 2007, 11:27am UTC](https://www.ruby-forum.com/t/macro-operator/113172 "2007-08-28T11:27:58Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 28, 2007, 11:27am UTC](https://www.ruby-forum.com/t/macro-operator/113172/1 "2007-08-28T11:27:58Z")
It is probably called different in ruby, but what I want to achive is: a1=10 r= ?(‘a’ + ‘1’) # ? is whatever, r should have value 10 by TheR ---
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 28, 2007, 11:37am UTC](https://www.ruby-forum.com/t/macro-operator/113172/2 "2007-08-28T11:37:42Z")
On 28 Aug 2007, at 18:28, Damjan R. wrote: > It is probably called different in ruby, but what I want to achive is: > > a1=10 > r= ?(‘a’ + ‘1’) # ? is whatever, r should have value 10 ? is eval: irb(main):001:0\> a1 = 10 =\> 10 irb(main):002:0\> r = eval(‘a’+‘1’) =\> 10 There are almost always better ways of doing something than using eval though. If you post what you are trying to do someone may be able to suggest an alternative. Alex G. Bioinformatics Center Kyoto University ---
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 28, 2007, 11:42am UTC](https://www.ruby-forum.com/t/macro-operator/113172/3 "2007-08-28T11:42:42Z")
On Behalf Of Damjan R.: # a1=10 # r= ?(‘a’ + ‘1’) # ? is whatever, r should have value 10 some simple ways, A. using eval > > a1=10 > > =\> 10 > > > macro=“a1+1” > > =\> “a1+1” > > > eval(macro) > > =\> 11 B. using proc or lambda > > macro2 = proc{a1+1} > > =\> #Proc:0xb7dd6bcc@:7(irb) > > > a1=100 > > =\> 100 > > > macro2.call > > =\> 101 C. using string interpolation > > puts “a1+1=#{a1+1}” > > a1+1=101 > > =\> nil pls test them further; i usually make stupid replies. kind regards -botp ---
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 28, 2007, 1:12pm UTC](https://www.ruby-forum.com/t/macro-operator/113172/4 "2007-08-28T13:12:00Z")
On 28.08.2007 13:03, Damjan R. wrote: > when 2; name2 > …etc Maybe you should change your database scheme to return an array name[] with all available name indices? - Matthias ---
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 28, 2007, 1:50pm UTC](https://www.ruby-forum.com/t/macro-operator/113172/5 "2007-08-28T13:50:03Z")
On 8/28/07, Damjan R. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > It is probably called different in ruby, but what I want to achive is: > > a1=10 > r= ?(‘a’ + ‘1’) # ? is whatever, r should have value 10 > sure ? equals "10 || " HTH Robert ---
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 28, 2007, 1:03pm UTC](https://www.ruby-forum.com/t/macro-operator/113172/6 "2007-08-28T13:03:38Z")
Thanks eval is good. What I have is database with fields name1,name2,name3,name4… and name=eval(“name#{num}”) works! Instead of something like name = case num when 1; name1 when 2; name2 …etc Thank you TheR ---
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 28, 2007, 7:31pm UTC](https://www.ruby-forum.com/t/macro-operator/113172/7 "2007-08-28T19:31:10Z")
On 28.08.2007 13:03, Damjan R. wrote: > Thanks eval is good. What I have is database with fields > name1,name2,name3,name4… and > > name=eval(“name#{num}”) I am not sure whether this is intentional but your variable “name” does not contain the name but the name’s value. > works! > > Instead of something like > name = case num > when 1; name1 > when 2; name2 > .etc Btw, you can also use Ruby’s intelligent string “counting”: irb(main):001:0\> n=“name1” =\> “name1” irb(main):002:0\> n.succ =\> “name2” irb(main):003:0\> n.succ.succ =\> “name3” irb(main):004:0\> n.succ.succ.succ =\> “name4” But I agree, this seems odd to have. You rather want a DB scheme where you store all your values for nameX in another table together with an index: owner\_id (FK to your major table) field\_index (numeric) value (whatever your type is) You probably also want a uniqueness constraint on (owner\_id, field\_index). Cheers robert ---
**Author:** ![ther](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/977dab/32.png) [@ther](https://www.ruby-forum.com/u/ther)\ **Post date:** [August 29, 2007, 2:56am UTC](https://www.ruby-forum.com/t/macro-operator/113172/8 "2007-08-29T02:56:09Z")
On Behalf Of Damjan R. # Thanks eval is good. What I have is database with fields # name1,name2,name3,name4… and i sense normalization problem. sooner or later you will run out of field names due to db constraints on max field counts. assumming, you have the table TABLE w the ff fields, TABLE: foo name1 name2 name3 name4 name5 aaa one two bbb one four … you can break it down to two tables TABLE1 and TABLE2 TABLE1: foo name aaa 1 aaa 3 bbb 1 bbb 4 … TABLE2: name value 1 one 2 two 3 three 4 four … of course, it’s possible i sensed it wrong 🙂 kind regards -botp