Ayende @ Rahien

Hi!
My name is Oren Eini
Founder of Hibernating Rhinos LTD and RavenDB.
You can reach me by phone or email:

ayende@ayende.com

+972 52-548-6969

, @ Q c

Posts: 10 | Comments: 37

filter by tags archive

Ayende's Design Guidelines: Rule #1

time to read 1 min | 167 words

When creating a generic method, strongly prefer to supply an overload that is not generic, can accept the types manually, and is externally visible.

Reasoning: The generic version often looks significantly better than the non generic version, but it comes with a cost. It assumes that you know, up front, what the types are. When you are writing any type of generic code, this is almost always not the case and your generic method is useless in that scenario.

Example: myContainer.RegisterComponent<IService, ServiceImpl>(); is a good syntax to have, but the problem with that is that it cannot be used with this code:

foreach(Type type in GetComponentTypes())
{
    myContainer.RegisterComponent<type.GetInterfaces()[0], type>();
}

Since we cannot use the generic overload, we need to resort to trickery such as MakeGenericMethod and friends. This is costly at runtime, obscure and generally make life harder all around.


Comments

Symon Rottem

I completely agree - this is something I've run into a few times and providing an API without non-generic alternatives just generates friction for the consumer.

Christopher Bennage

I guess the context here is when you are publishing an API?

In a project where I control and consume the code base, it's YAGNI.

Ayende Rahien

Yes, this is for published API.

If you control the code, it doesn't really matter, since you can always change that.

Nevertheless, you need to carefully consider what you believe a published API is

Andrey Shchekin

Exactly. http://api.castleproject.org/html/MCastleMicroKernelDefaultKernelResolveServices1.htm immediatelly comes to mind.

Andrey Shchekin

Exactly. http://api.castleproject.org/html/MCastleMicroKernelDefaultKernelResolveServices1.htm immediatelly comes to mind.

Francois Tanguay

That's why I wished there was a way to promote a type object into a generic scope:

foreach(Type type in GetComponentTypes())

{

// New using scope keyword!

using<TInterface with type.GetInterfaces()[0], T with type>()

{ 

  myContainer.RegisterComponent<TInterface, T>(); 

}

}

Comment preview

Comments have been closed on this topic.

FUTURE POSTS

  1. Production postmortem: The case of the memory eater and high load - about one day from now
  2. Production postmortem: The case of the lying configuration file - 2 days from now
  3. Production postmortem: The industry at large - 3 days from now
  4. The insidious cost of allocations - 4 days from now
  5. Find the bug: The concurrent memory buster - 5 days from now

And 4 more posts are pending...

There are posts all the way to Sep 10, 2015

RECENT SERIES

  1. Find the bug (5):
    20 Apr 2011 - Why do I get a Null Reference Exception?
  2. Production postmortem (10):
    14 Aug 2015 - The case of the man in the middle
  3. What is new in RavenDB 3.5 (7):
    12 Aug 2015 - Monitoring support
  4. Career planning (6):
    24 Jul 2015 - The immortal choices aren't
View all series

Syndication

Main feed Feed Stats
Comments feed   Comments Feed Stats