''Macro'' operator

[Damjan Rems]

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

 

[Alex Gutteridge]

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 Gutteridge

Bioinformatics Center
Kyoto University

 

[Peña, Botp]

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[Damjan Rems]

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

 

[Matthias Wächter]

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

Maybe you should change your database scheme to return an array
name[] with all available name indices?

- Matthias

 

[Robert Dober]

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

 

[Robert Klemme]

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

 

[Peña, Botp]

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