Comments on: Clean Code Talks – Inheritance, Polymorphism, & Testing

By: ayumilove

ayumilove — Mon, 03 May 2010 22:46:21 +0000

for instance:
function createProduct (type : String) : Product
{
switch(type)
{
case PRODUCT_A : return new ProductA();
case PRODUCT_B : return new ProductB();
}
return new NullProduct();
}

By: ayumilove

ayumilove — Mon, 03 May 2010 22:44:26 +0000

my factory has a switch case (if-else statement), how would i use polymorphism to solve this?

By: misko

misko — Mon, 03 May 2010 16:31:14 +0000

@ayumilove, I don’t think we ever recorded that one.

By: ayumilove

ayumilove — Sun, 02 May 2010 07:06:58 +0000

In the video, the presenter mention something about not overusing polymorphism that causes runaway subclassing (as in too many classes)

Where can I find that google clean code talk video focussing on that particular subject?

By: Se hace camino al andar… » Blog Archive » Muerte al if

Se hace camino al andar… » Blog Archive » Muerte al if — Mon, 01 Mar 2010 23:46:16 +0000

[...] blog. Os recomiendo encarecidamente la siguiente entrada del blog de Miško Hevery titulada “Inheritance, Polymorphism, & Testing” (sí, lo siento, en inglés) porque no tiene desperdicio. Tranquilos, si no os queréis [...]

By: misko

misko — Thu, 05 Nov 2009 15:44:59 +0000

@Sarah,

Glad to be of service.

By: Sarah Xia

Sarah Xia — Thu, 05 Nov 2009 11:02:38 +0000

Hi Misko,

Thanks for the great talk!

I watched it on Youtube last night and couldn’t agree with you more. I went to work this morning and looked at a project I implemented. Boy, so many if statements, so I tried to use polymorphism, and then it was so much easier to understand. My code is so much clearer! I was in a really happy mood for the whole day..even now!

I feel like my skill somewhere moved up to another level. Thank you!

By: mrclay.org » Archive » Miško Hevery Programming Talks

mrclay.org » Archive » Miško Hevery Programming Talks — Mon, 29 Jun 2009 18:35:27 +0000

[...] Inheritance, Polymorphism, & Testing [...]

By: misko

misko — Tue, 20 Jan 2009 03:50:42 +0000

@Scott, in most cases the conditional ends up in the factory, but sometimes the factory is created polymorphically, so the if ends up even higher up.

By: Scott

Scott — Tue, 20 Jan 2009 02:51:04 +0000

Hi Misko;

I’ve been watching the Clean Code Talks on YouTube and learning lots. Thanks for the effort.

Sorry to comment late for this posting, but I’m still trying to
understand something about replacing conditionals with polymorphism.

I understand how you can extract each “leg” of a conditional into its
own class, then instantiate the behavior that you want from a factory
class.

What I don’t understand is how do the factories know which classes to
instantiate? It seems like the ideal place for a conditional.

In Ruby we have a few meta helpers like this:

class PeelerFactory thin_skinned_fruits = ["apple", "pear"] my_fruits = []
thin_skinned_fruits.each do |f|
my_fruits << Object.const_get(”#{f.capitalize}Peeler”).new
endendclass ApplePeeler; endclass PearPeeler; end

Is this what you have in mind? Or is it OK
to use conditionals in factory classes?class PeelerFactory

def initialize(type) @type = type end def peeler case @type when “apple” ApplePeeler.new when “pear” PearPeeler.new end end
end
class ApplePeeler; end
class PearPeeler; end

Thanks!Scott