I am learning ruby and wondering if it is possible to create a var from a variable combined with a string.
a = "variable"
a+"_name" = []
variable_name => []
Thanks, CG
Add a comment
|
3 Answers
You can do this easily with an instance variable as such:
>> a = "variable"
=> "variable"
>> instance_variable_set(:"@#{a}_name", [])
=> []
>> @variable_name
=> []
If you're curious about why this is easier to do with an ivar, read up about Ruby variable binding and scoping rules.
2 Comments
Cory Gwin
What is the # doing in this @#{a}_name and is the : setting it as a symbol?
mu is too short
@CoryGwin: The leading
: makes it a symbol, the #{} inside the double quoted string is just normal string interpolation.But don't do that. So much easier and better to use a hash:
variable = {}
variable['name'] = []
or
vars = {}
vars[["variable", "name"]] = []
3 Comments
ziq
Yeah hash is strongly recommended when comes to undelcared var or methods. It can take care of it
Cory Gwin
I take it this is for name spacing? What if it is part of a class, or I guess object instance?
DGM
THis question has been asked before, and I have yet to see a good reason to do it. Php had some sort of variable interpolation, and I suspect most of the questions like this are people bringing that abomination into ruby... ;)
Incase you still want to do with variables:
>> a = 'variable'
=> "variable"
>> eval(a + '_name=[]')
=> []
>> variable_name
=> []
Hope you understand how evil eval is!
