Comments on: Polymorphism and the switch statement http://www.udidahan.com/2006/08/04/polymorphism-and-the-switch-statement/ Enterprise Development Expert & SOA Specialist Wed, 08 Sep 2010 18:14:32 -0500 http://wordpress.org/?v=2.8.4 hourly 1 By: Udi Dahan - The Software Simplist http://www.udidahan.com/2006/08/04/polymorphism-and-the-switch-statement/comment-page-1/#comment-350 Udi Dahan - The Software Simplist Fri, 04 Aug 2006 12:32:27 +0000 http://wp_630.weblogs.us/archives/306#comment-350 John, The reason it can't/shouldn't be instantiated with an object implementing IEntity is that it receives the type of entity to be created (as per the 'new' command). What this means is that these handlers are created at system startup as "singletons" and will be handling the given commands for those entity types. The generic class means I don't have to create an implementation for every entity type in the system. John,

The reason it can’t/shouldn’t be instantiated with an object implementing IEntity is that it receives the type of entity to be created (as per the ‘new’ command). What this means is that these handlers are created at system startup as “singletons” and will be handling the given commands for those entity types.

The generic class means I don’t have to create an implementation for every entity type in the system.

]]> By: John Wood http://www.udidahan.com/2006/08/04/polymorphism-and-the-switch-statement/comment-page-1/#comment-349 John Wood Fri, 04 Aug 2006 02:10:57 +0000 http://wp_630.weblogs.us/archives/306#comment-349 Firstly that does look a better implementation, it's obvious that your solution was well suited to polymorphism, even though not all switch statements are. Secondly perhaps I'm missing something but your polymorphic implementation looks more complex than it needs to be. Why not have one command handler class that is instantiated with an IEntity, I don't see what you gain from it being a generic class. And why do you need the if statement to check the type? Surely you can run builder.Build with an IEntityView taking any IEntity type. Firstly that does look a better implementation, it’s obvious that your solution was well suited to polymorphism, even though not all switch statements are. Secondly perhaps I’m missing something but your polymorphic implementation looks more complex than it needs to be. Why not have one command handler class that is instantiated with an IEntity, I don’t see what you gain from it being a generic class. And why do you need the if statement to check the type? Surely you can run builder.Build with an IEntityView taking any IEntity type.

]]>