[Ironruby-core] A nicer syntax for generic extension methods

Ivan Porto Carrero ivan at whiterabbitconsulting.eu
Wed Feb 3 11:49:16 EST 2010


For lightspeed I wrote an internal dsl that allows you to query similarly to
the regular api but no special module for linq stuff. I skipped linq
altogether didn't need it there.

so what I created there is (It's in the asp.net mvc chapter btw)

find_all User do
   where a(:name).like("ivan%") & a(:age) > 23
   order_by :name.desc
end

that may be wrong but it's close to something like that..
---
Met vriendelijke groeten - Best regards - Salutations
Ivan Porto Carrero
Blog: http://flanders.co.nz
Twitter: http://twitter.com/casualjim
Author of IronRuby in Action (http://manning.com/carrero)



On Wed, Feb 3, 2010 at 4:01 PM, Ryan Riley <ryan.riley at panesofglass.org>wrote:

> Thanks, Ivan. That's awesome ... that's just like F#. I should have
> realized it would be that simple. I'll post this to the Delegates section of
> the .NET interop page on the wiki, since it currently doesn't exist.
>
> Also, I noticed you alluded to something similar in IronRuby in Action
> where you talk about LightSpeed, but I couldn't find anything in the MEAP
> copy I have. If I am able to spin up a few LINQ samples (probably Rx, Pfx,
> and/or XLinq), I'll shoot them your way, if you are interested.
>
> Cheers!
>
> Ryan Riley
>
> Email: ryan.riley at panesofglass.org
> LinkedIn: http://www.linkedin.com/in/ryanriley
> Blog: http://wizardsofsmart.net/
> Twitter: @panesofglass
> Website: http://panesofglass.org/
>
>
> On Tue, Feb 2, 2010 at 11:40 PM, Ivan Porto Carrero <
> ivan at whiterabbitconsulting.eu> wrote:
>
>> just pass your block to the constructor of a delegate and you should be
>> good to go
>>
>> Action.new { more_work_here }
>> ---
>> Met vriendelijke groeten - Best regards - Salutations
>> Ivan Porto Carrero
>> Blog: http://flanders.co.nz
>> Twitter: http://twitter.com/casualjim
>> Author of IronRuby in Action (http://manning.com/carrero)
>>
>>
>>
>>
>> On Tue, Feb 2, 2010 at 11:38 PM, Ryan Riley <ryan.riley at panesofglass.org>wrote:
>>
>>> That's fantastic, Tomas, thanks! Is there any way to pass a block,
>>> lambda, or Proc into the slot for the delegate, or perhaps a way to create a
>>> .NET delegate (or Expression) from a block, lambda, or Proc?
>>>
>>> Thanks,
>>>
>>> Ryan Riley
>>>
>>> Email: ryan.riley at panesofglass.org
>>> LinkedIn: http://www.linkedin.com/in/ryanriley
>>> Blog: http://wizardsofsmart.net/
>>> Twitter: @panesofglass
>>> Website: http://panesofglass.org/
>>>
>>>
>>> On Tue, Feb 2, 2010 at 1:36 AM, Tomas Matousek <
>>> Tomas.Matousek at microsoft.com> wrote:
>>>
>>>> Actually, you can add Ruby methods to List<T> … IronRuby type system
>>>> does some magic for you J:
>>>>
>>>>
>>>>
>>>> >>> include System::Collections::Generic
>>>>
>>>> => Object
>>>>
>>>> >>> List[Fixnum].included_modules
>>>>
>>>> => [System::Collections::Generic::List[T],
>>>> System::Collections::Generic::IList[Fixnum],
>>>> System::Collections::Generic::IList[T],
>>>> System::Collections::Generic::ICollection[Fixnum],
>>>> System::Collections::Generic::ICollection[T],
>>>> System::Collections::Generic::IEnumerable[Fixnum],
>>>> System::Collections::Generic::IEnumerable[T],
>>>> System::Collections::IEnumerable, Enumerable, System::Collections::IList,
>>>> System::Collections::ICollection, System::Collections::Generic, Kernel]
>>>>
>>>>
>>>>
>>>> As you can see the List<> generic type definition is treated as a module
>>>> that is mixed in each of its instantiations. Although there are no
>>>> predefined methods on it you can open it and add some. First we need to get
>>>> Ruby class for List<T>. If you index System.Collections.Generic.List by a
>>>> fixnum instead of a class/module you’ll get the generic definition of arity
>>>> 1. Let’s name it ListOfT:
>>>>
>>>>
>>>>
>>>> >>> ListOfT = List[1]
>>>>
>>>>
>>>>
>>>> And then we can open it up:
>>>>
>>>>
>>>>
>>>> >>> module ListOfT
>>>>
>>>> ...   def size
>>>>
>>>> ...     count
>>>>
>>>> ...   end
>>>>
>>>> ... end
>>>>
>>>> => nil
>>>>
>>>> >>> l = List[Fixnum].new
>>>>
>>>> => []
>>>>
>>>> >>> l.add(1)
>>>>
>>>> => nil
>>>>
>>>> >>> l.add(2)
>>>>
>>>> => nil
>>>>
>>>> >>> l.size
>>>>
>>>> => 2
>>>>
>>>>
>>>>
>>>> Tomas
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> *From:* ironruby-core-bounces at rubyforge.org [mailto:
>>>> ironruby-core-bounces at rubyforge.org] *On Behalf Of *Orion Edwards
>>>> *Sent:* Monday, February 01, 2010 6:31 PM
>>>> *To:* ironruby-core at rubyforge.org
>>>> *Subject:* Re: [Ironruby-core] A nicer syntax for generic extension
>>>> methods
>>>>
>>>>
>>>>
>>>> IIRC you can open "concrete" generics, but not "open" ones: In plain
>>>> english this means you can add methods to List<string> but not List<T>.
>>>>
>>>>
>>>>
>>>> This is essentially because List<T> isn't a real type in the CLR, it's
>>>> basically some metadata that can be used to build a real type when the T is
>>>> supplied.
>>>>
>>>>
>>>>
>>>> You could as an alternative add methods to the underlying non-generic
>>>> IEnumerable interface, but then you'd have to do some run-time reflection to
>>>> figure out that your List is actually a List<string>... This is probably not
>>>> nice.
>>>>
>>>>
>>>>
>>>> In theory when CLR4 lands and has support for co/contra variant
>>>> generics, List<object> should match List<string> and everything else, but I
>>>> don't know if IronRuby would also work for this?
>>>>
>>>>
>>>>
>>>> Good luck
>>>>
>>>> On Tue, Feb 2, 2010 at 7:52 AM, Ryan Riley <ryan.riley at panesofglass.org>
>>>> wrote:
>>>>
>>>> I have been trying to figure out how to Rubify generic extension methods
>>>> for use with the likes of Rx, Open XML SDK, etc. Ivan went over it a bit
>>>> with me this weekend, but I'm still having difficulty including a module
>>>> within a .NET type. Is that even possible?
>>>>
>>>>
>>>>
>>>> ...
>>>>
>>>>
>>>>
>>>> The questions I'm not able to answer are:
>>>>
>>>>    1. Can I somehow open up a .NET class, say
>>>>    System::Collections::Generic::List[T] and include the EnumerableExtensions?
>>>>    So far, I'm finding that's a no.
>>>>    2. How do I hook in the included(base) method above? I'm assuming
>>>>    that's a one-time call, but I don't see anywhere that it's called when a
>>>>    module is included. Do I need to use a before_filter or perform that action
>>>>    at the beginning of the linq_select method?
>>>>
>>>>
>>>>
>>>> Thanks!
>>>>
>>>>
>>>> Ryan Riley
>>>>
>>>> Email: ryan.riley at panesofglass.org
>>>> LinkedIn: http://www.linkedin.com/in/ryanriley
>>>> Blog: http://wizardsofsmart.net/
>>>> Twitter: @panesofglass
>>>> Website: http://panesofglass.org/
>>>>
>>>> _______________________________________________
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>>>>
>>>>
>>>>
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>>>>
>>>
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