Dammit Paul, just as I was typing this out ;)
There is a limitation in Pauls method though with nested Classes/Modules. If
they are nested you can use something like:
# Get a class based on a string, handles :: module nesting
def self.class_from_string(str)
str.split('::').inject(Object) do |mod, class_name|
mod.const_get(class_name)
end
end
Which will handle the nesting.
Samuel Richardson
www.richardson.co.nz | 0405 472 748
On Thu, Aug 18, 2011 at 3:17 PM, Paul Annesley <[email protected]> wrote:
> Check out
> http://api.rubyonrails.org/classes/ActiveSupport/Inflector.html#method-i-constantize
> (including
> the source code).
>
> It hinges on Kernel.get_const(string)
>
> - Paul
>
>
> On Thursday, 18 August 2011 at 3:12 PM, Sonia Hamilton wrote:
>
> I'm just wondering about the Ruby way of instantiating a class when the
> class name is in a string?
>
> For example:
>
> def build_classname
> # reality is a bit more complex...
> "Foo" + "Builder"
> end
> class_name = build_classname
>
> Then I want to instantiate an instance based on class_name, ie the
> equivalent of:
>
> obj = FooBuilder.new
> # obj = class_name.new XX FAIL
>
> Google isn't helping - ruby + classname + instantiate + string brings up
> all sorts of random stuff :-) I was thinking of doing some eval
> awfulness, but there's got to be a Ruby way...
>
> --
> Sonia Hamilton
>
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