Hi,
I am trying to pass a variable to a dynamically declared method like:
eval(def test(name)
puts name
end
test 'joe')
but it does not work.
Is there a way to do this?
views:
96answers:
3
+9
A:
eval expects a string. The following should work fine:
eval "def test(name)
puts name
end
test 'joe'"
Brian McKenna
2010-06-08 04:10:35
Thanks for reminding Brian. It works. Not sure why I missed that.
Nick
2010-06-08 16:39:08
A:
I am a little confused on what you are trying to do. If you are trying to define a method with eval that can take a parameter here is the example:
eval "def test(name)
puts name
end"
test 'joe'
If you want to use eval to define a method that is more dynamic and uses a variable, since as Brian pointed out eval takes a string you would do something like this:
test_name = 'joe'
eval "def test
puts '#{test_name}'
end"
test
ScottD
2010-06-08 04:14:26
Either works, depending on what the OP wants. Clearly he'll be interpolating something somewhere, since, otherwise, why use `eval`?
Matchu
2010-06-08 04:17:55
I was trying to read a method stored in the database and then execute it with parameters.
Nick
2010-06-08 16:39:55
Do you know that the parameters are and their order before you read it in? If so then using eval with the string should work.
ScottD
2010-06-08 17:07:02
+6
A:
If you want to declare a method dynamically then a better way to do that is to use define_method instead of eval, like so
define_method(:test) do |name|
name
end
test 'joe'
#=> joe
Don't use eval unless it is absolutely necessary and you are 120% sure that it is safe. Even if you are 120% sure that it is safe, still try to look for other options and if you find one then use that instead of eval.
nas
2010-06-08 05:27:03