AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Subtypes          AppletTalk.com Forum Index -> Java Discussions View previous topic :: View next topic   Author Message apple_amateur Guest Posted: Sat Oct 25, 2008 1:56 pm    Post subject: Subtypes Hi all, I need some help to understand the following statement, which is from a respectable source. "A sub-typing mechanism is sound if and only if a method implementation is protected by the types of its formal parameters." In Java, from what I understand, the types of arguments used in each method of a subtype class must be the same as the argument types in comparable methods of the supertype class. Does the above statement imply that a system based on a sound sub-typing mechanism should have subclasses that have matching methods to their super classes? If so, doesn't it mean that aspects like overloading are frowned upon? Why is sub-typing important? Thank you, I hope that the above questions aren't too stupid and irrelevant. aa Back to top Donkey Hottie Guest Posted: Wed Oct 29, 2008 1:32 am    Post subject: Re: Subtypes apple_amateur <angedward3 (AT) gmail (DOT) com> wrote in news:6bf1a684-6a46-4e99-8503- 91dc15cd3c2d (AT) k7g2000hsd (DOT) googlegroups.com: Quote: Hi all, I need some help to understand the following statement, which is from a respectable source. "A sub-typing mechanism is sound if and only if a method implementation is protected by the types of its formal parameters." In Java, from what I understand, the types of arguments used in each method of a subtype class must be the same as the argument types in comparable methods of the supertype class. Does the above statement imply that a system based on a sound sub-typing mechanism should have subclasses that have matching methods to their super classes? If so, doesn't it mean that aspects like overloading are frowned upon? Why is sub-typing important? Thank you, I hope that the above questions aren't too stupid and irrelevant. aa Please ask this in comp.lang.java.programmer alt.comp.lang.java is quite dead and irrelevant. Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> Java Discussions All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.