<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=""><br class=""><div><blockquote type="cite" class=""><div class="">On Jan 14, 2016, at 9:22 AM, Jo Albright 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=""><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="">This is a thought from a current problem I am running into (and have ran into in the past).<div class=""><br class=""></div><div class="">If you want to write any code using a library, you must have that library imported into the file. Totally cool with this for most cases.</div><div class=""><br class=""></div><div class="">Situation :</div><div class=""><br class=""></div><div class="">Building a third party library that can be used by others to simplify working with server APIs. I want to give the developer an option to use another third party library within mine. However, I don’t want my library to depend on the other library.</div><div class=""><br class=""></div><div class="">Possible Solution :</div><div class=""><br class=""></div><div class="">Add a system that does two things. 1) Checks for a library and if found imports it into file. 2) Checks if library is imported and allows source kit to parse conditional scope.</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">@importable</span><span style="" class=""> ThirdPartyLibrary </span>// would check if library is added to project and import it</div></div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(120, 73, 42);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">if</span><span style="" class=""> </span>#imported<span style="" class="">(</span><span style="" class="">ThirdPartyLibrary</span><span style="" class="">) {</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""> <br class="webkit-block-placeholder"></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="" class=""> </span>// would check if library is imported before source kit parses scope</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""> </div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""> // if library is not imported</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="" class=""> </span>// scope would remain unparsed</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="" class=""> </span>// scope could be removed as if it were a comment</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""> <br class="webkit-block-placeholder"></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class="">}</div></div><div class=""><br class=""></div><div class="">Thanks.<br class=""></div></div></div></blockquote></div><br class=""><div class="">Interesting idea. Unless I'm misunderstanding something, it seems to me you could kill both birds with one stone. If we add an 'importable' predicate to the '#if' language, then you can already use that to conditionalize the import:</div><div class=""><br class=""></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div class="">#if importable(ThirdPartyLibrary)</div><div class="">import ThirdPartyLibrary</div><div class="">/* decls that depend on library */</div><div class="">#endif</div></blockquote><div class=""><br class=""></div><div class="">-Joe</div></body></html>