http://ayende.comAyende @ RahienCopyright (C) Ayende Rahien 2004 - 2021 (c) 202660Sorry, badly worded. I mean if you need to use strategy pattern, e.g. ICargoRouteCalculatorhttp://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment18http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment18Fri, 17 Feb 2012 12:21:46 GMThammerip , I am not sure that I am following the questionhttp://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment17http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment17Fri, 17 Feb 2012 12:08:50 GMTI presume you are happy to allow additional abstractions for strategies identified within the system?http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment16http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment16Fri, 17 Feb 2012 11:54:01 GMTAndrey, I wouldn't :-) I am discussing this in detail in a future post.http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment15http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment15Wed, 15 Feb 2012 09:40:15 GMTHow would you actually create commands though (in a system that uses dependency injection)?http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment14http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment14Tue, 14 Feb 2012 22:35:03 GMTDaniel, Yes, you are doing it wrong :-) You don't need all of that for testing, I am actually going to touch testing specifically in a later posthttp://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment13http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment13Tue, 14 Feb 2012 13:34:07 GMTOren, I totally agree with except for the testing thing. I often find myself introducing abstractions and interfaces just for testing purposes, so that I can stub and mock them out in my tests. What does that mean? Do I structure my code the wrong way? I'm absolutely sure that I don't generally test _too_ much, so I guess I probably test the wrong things or have my code layed out wrong.http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment12http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment12Tue, 14 Feb 2012 13:18:09 GMTBetty, No, they are all infrastructure. If you have _many_ of them, that indicates a problem with either bad infrastructure or wrong headed use of it.http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment11http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment11Tue, 14 Feb 2012 07:35:48 GMTGiven a standard ASP.NET MVC website would you consider *Custom* ActionFilters, ActionResults, HtmlHelpers, ModelBinders, Validators, Route Constraints etc in your list of abstractions or are they just infrastructure? If they are just infrastructure how are they different from most the things you listed?http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment10http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment10Tue, 14 Feb 2012 03:45:55 GMTI second Chris Wright. Can you please clarify Oren!http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment9http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment9Mon, 13 Feb 2012 23:46:37 GMTIt's a tad ambiguous whether you mean to say "I don't like this approach that I just outlined with the Command base class and various implementations; and I'll discuss why in my next post", or "I don't like the approach that the sample application took; and I'll discuss in further detail why I dislike this approach in my next post".http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment8http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment8Mon, 13 Feb 2012 22:23:33 GMTI agree with the general premise. Having a small number of the right kind of abstractions is important for maintaining the coherence of code organization. Events provide endpoints for reactive code to attach Tasks or Commands as responses. You refer to SL/WPF-style Commands, but what do you mean by Tasks? TPL Tasks? Commands packaged as separate classes are often too granular, but delegate commands are possible as well. I also occasionally invoke remote commands on a server in the same way I invoke queries. What drives me nuts is the inconsistency of seeing XyzService alongside AbcManager, etc. http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment7http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment7Mon, 13 Feb 2012 14:36:06 GMTKhalid, No, those aren't your own things, they belong to the infrastructure.http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment6http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment6Mon, 13 Feb 2012 14:33:14 GMTNice one. I think this post will be a game changer for a lot of people.http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment5http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment5Mon, 13 Feb 2012 13:53:55 GMTWould you qualify any use of an interface as an abstraction that goes against your six to twelve count? For example, if I use IDocumentSession or IQueryable instead of the concrete implementation in my code, did I just use one up? Or is it more about creating wrapper classes for encapsulating logic?http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment4http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment4Mon, 13 Feb 2012 13:09:58 GMTYou're absolutely right. IBookingService is a terrible interface. It should have been called IBookingManager ! :-)http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment3http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment3Mon, 13 Feb 2012 11:35:13 GMTOmer, yes, fixed http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment2http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment2Mon, 13 Feb 2012 11:17:20 GMT"In most applications, I like to have a very small number of abstractions. Usually in the order of half a dozen to a dozen (top!). I usually thing about them like this:" You meant think and not thing.http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment1http://ayende.com/154081/limit-your-abstractions-you-only-get-six-to-a-dozen-in-the-entire-app#comment1Mon, 13 Feb 2012 10:20:04 GMT