What I want to do is name variables dynamically like:
def instance(instance)
@instance = instance #@instance isn't actually a variable called @instance, rather a variable called @whatever was passed as an argument
end
How can I do this?
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possible duplicate of Dynamically set local variables in Rubycoreyward– coreyward2012-05-05 01:52:57 +00:00Commented May 5, 2012 at 1:52
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3 Answers
Use instance_variable_set.
varname = '@foo'
value = 'bar'
self.instance_variable_set varname, value
@foo # => "bar"
Or if you don't want the caller to have to supply the '@':
varname = 'foo'
value = 'bar'
self.instance_variable_set "@#{varname}", value
@foo # => "bar"
Comments
If I understand correctly you want to use "instance_variable_set":
class A
end
a = A.new
a.instance_variable_set("@whatever", "foo")
a.instance_variable_get("@whatever") #=> "foo"
Comments
You can't really.
You could play around with eval, but really, it won't be readable.
Use the correct if or use a hash instead.
# With Hash:
values = {}
a = :foo
values[a] = "bar"
values[:foo] # => "bar"
# With if
calc = "bar"
if a_is_foo
foo = calc
else
oof = calc
end
foo # => "bar"
answered May 5, 2012 at 1:48
Marc-André Lafortune
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3 Comments
Bobby Tables
how? what exactly do you mean?
d11wtq
He means:
var = :a; hash = { var => 'foo' }; hash[var] = 'bar'; hash[var];d11wtq
I would never suggest the use of
eval for this. It's a design flaw and eval is dangerous in the wrong hands ;)