<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="">On Feb 14, 2016, at 12:02 PM, plx via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><div><blockquote type="cite" class=""><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="">As far as I have followed it, it does seem that it’s only `synchronized`-style behaviors that are fundamentally-problematic under composition; that is, using the terminology in the proposal, linear behavior composition would work fine, and to my eyes most behaviors are “linear”.</span></div></blockquote></div><br class=""><div class="">Behaviors that make synchronization promises are an obvious problem with composition, but there are also subtle issues with other compositions. Consider the composition of `lazy` with `didSet`—if you apply `didSet` inside `lazy`, you'll observe the lazy initialization as a "set" of the lazy storage, whereas you won't if you apply `lazy` inside `didSet`.</div><div class=""><br class=""></div><div class="">-Joe</div></body></html>