<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=""><div class="">Hi S/E,</div><div class=""><br class=""></div><div class="">I’ve raised a rather speculative PR suggesting a hook be added to stdlib</div><div class="">that would allow users to experiment with error recovery in their apps.</div><div class="">I’ve been asked to put it forward on Swift Evolution to gather opinions</div><div class="">from the wider community about such a design.</div><div class=""><br class=""></div><div class=""><a href="https://github.com/apple/swift/pull/12025" class="">https://github.com/apple/swift/pull/12025</a></div><div class=""><br class=""></div><div class="">Ultimately, it comes down to being able to do something like this:</div><div class=""><br class=""></div><div class=""><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> <span class="" style="color: rgb(186, 45, 162);">do</span> {</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> <span class="" style="color: rgb(186, 45, 162);">try</span> <span class="" style="color: rgb(79, 129, 135);">Fortify</span>.<span class="" style="color: rgb(49, 89, 93);">exec</span> {</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> <span class="" style="color: rgb(186, 45, 162);">var</span> a: <span class="" style="color: rgb(112, 61, 170);">String</span>!</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> a = a!</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> }</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> }</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> <span class="" style="color: rgb(186, 45, 162);">catch</span> {</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> <span class="" style="color: rgb(62, 30, 129);">NSLog</span>(<span class="" style="color: rgb(209, 47, 27);">"Caught exception: </span>\<span class="" style="color: rgb(209, 47, 27);">(</span>error<span class="" style="color: rgb(209, 47, 27);">)"</span>)</div><div class="" style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"> }</div></div><div class=""><br class=""></div><div class="">This was primarily intended for user in "Swift on the server" but could also</div><div class="">help avoid crashes in the mobile domain. The rationale and mechanics</div><div class="">are written up at the following url:</div><div class=""><br class=""></div><div class=""><a href="http://johnholdsworth.com/fortify.html" class="">http://johnholdsworth.com/fortify.html</a></div><div class=""><br class=""></div><div class="">I'll accept this won’t be everybody’s cup of tea but at this stage this is</div><div class="">only an opt-in facilitating patch. Developers need not subject their apps</div><div class="">to this approach which requires a separate experimental implementation.</div><div class=""><br class=""></div><div class="">The recovery is reasonably well behaved except it will not recover </div><div class="">objects and system resources used in intermediate frames, It’s not</div><div class="">as random as something like, for example, trying to cancel a thread.</div><div class=""><br class=""></div><div class="">The debate about whether apps should try to soldier on when something</div><div class="">is clearly amiss is a stylistic one about which there will be a spectrum of</div><div class="">opinions. The arguments weigh more in favour in the server domain.</div><div class=""><br class=""></div><div class="">Over to you,</div><div class=""><br class=""></div><div class="">John</div><div class=""><br class=""></div></body></html>