<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">The “module” in this case being the same source file.<div class=""><br class=""></div><div class="">i.e. Family.scala </div><div class=""><br class=""></div><div class="">contains a sealed class called “Parent” which is sealed, </div><div class=""><br class=""></div><div class="">you could have another class in their called “Child” which inherits from the parent. </div><div class=""><br class=""></div><div class="">but you cannot write another class and inherit from it in Sibling.scala.</div><div class=""><br class=""></div><div class="">Since only the library writer has access to Family.scala and the classes are sealed by default - it is effectively the same as final by default other than it does not restrict the actual writer of the library not to inherit from their own class.</div><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 2015-12-24, at 1:45:45, Matthew Johnson <<a href="mailto:matthew@anandabits.com" class="">matthew@anandabits.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Dec 23, 2015, at 12:43 PM, Craig Cruden <<a href="mailto:ccruden@novafore.com" class="">ccruden@novafore.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">I thought sealed and final were effectively the same thing for production code, which is why it confuses me when you say final is right anything less including sealed is not.<div class=""><br class=""></div><div class="">In Scala at least sealed is final with the exception that subclasses within the same source file are allowed. When it is compiled and shipped - you can no longer modify that source file….. </div></div></div></blockquote><div class=""><br class=""></div><div class="">They are not at all the same. The difference is that with sealed you cannot inherit from classes in <b class="">other</b> modules which are not explicitly marked `inheritable`, but you <b class="">can</b> inherit from classes in your own module that are not explicitly marked `inheritable`. That is a big difference.</div><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><div class=""><div class=""><blockquote type="cite" class=""><div class="">On 2015-12-24, at 1:36:01, Matthew Johnson via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">I<span class="Apple-converted-space"> </span></span><b class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">strongly</b><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""> feel that I shouldn’t pay a price in production code in order to better support those use cases. IMO ‘final’ is the right default for production code and we pay a price if the default is anything less, including ‘sealed’. </span></div></blockquote></div><br class=""></div></div></div></div></blockquote></div><br class=""></div></div></blockquote></div><br class=""></div></body></html>