<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap:break-word"><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">I’ve skimmed through it just now. What we are talking about is “Logic Failures” and that is handled in three small paragraphs of the ErrorHandling document the rest (universal, recoverable, simple domain errors) are separate. Basically, to summarize the Logic Failures section, there is no rule yet set down “yet".</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">Quote:</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><span style="color:rgb(36,41,46);font-family:-apple-system,system-ui,'Segoe UI',Helvetica,Arial,sans-serif,'Apple Color Emoji','Segoe UI Emoji','Segoe UI Symbol';font-size:16px;font-variant-ligatures:normal">The correct handling of these error conditions is an open question and is not a focus of this proposal. Should we decide to make them recoverable, they will likely follow the same implementation mechanism as universal errors, if not necessarily the same language rules."</span></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">The “universal errors” section referred to is equally open-ended. To sum up the two sections, there seems to be an implicit proposal to add universal exceptions in the future (“logic failures” and Obj-C/C++ exception support) in the future, with a few concerns about discouraging its use. My concern about webservers is mentioned directly in the “Logic Failures” section, "High-reliability systems may need some way to limp on even after an assertion failure.”.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">So, granted that the proposal is more or less already there, I would propose typed exceptions for "Logic Failures", Obj-C, and C++ exceptions.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto">If someone needs more discouragement than that, then all that needs to be done is to make the syntax cumbersome. Like having to pass a closure to a function instead of the clean do{} catch{} syntax, which btw is the way that it is done now for those who need to catch Obj-C exceptions from Swift. See <a href="http://stackoverflow.com/questions/35119531/catch-objective-c-exception-in-swift">http://stackoverflow.com/questions/35119531/catch-objective-c-exception-in-swift</a> for that. I can say that I’ve used it myself and that I am extremely discouraged from using it to throw an NSException from Swift, or even to catch the Obj-C exceptions for that matter.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto"><br></div> <div id="bloop_sign_1489352966894070272" class="bloop_sign"></div> <br><p class="airmail_on">On March 12, 2017 at 3:20:41 PM, Austin Zheng (<a href="mailto:austinzheng@gmail.com">austinzheng@gmail.com</a>) wrote:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap:break-word" class=""><div></div><div>
<title></title>
If you want improved error handling, feel free to put together a
proposal once Swift 4 phase 2 is over. A good proposal should take
into account the reasons Swift's error handling was designed as it
currently is (<a href="https://github.com/apple/swift/blob/master/docs/ErrorHandlingRationale.rst" class="">https://github.com/apple/swift/blob/master/docs/ErrorHandlingRationale.rst</a>)
<div class=""><br class=""></div>
<div class="">Otherwise, if you really need to build a web server
framework that can swallow any sort of application logic without
choking, perhaps Swift as it currently stands isn't the best tool
for the job.<br class="">
<div class=""><br class=""></div>
<div class="">Best,</div>
<div class="">Austin</div>
<div class=""><br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Mar 12, 2017, at 12:06 PM, Elijah Johnson
<<a href="mailto:ejrx7753@gmail.com" class="">ejrx7753@gmail.com</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class="">The problem for using Swift on the server is one of these
optionals (or array index out of bounds error, or cast from Int to
UInt error) would crash the entire server directing many requests.
Granted, thats not Apple’s busininess, but it is pretty much
standad in a modern webserver never to crash, and whoever is
developing servers will find they don’t have the necessary power to
do that. Some languages like PHP have a unique process per-request
style, but that phrohibits shared data. One could do the same with
Swift, but it would be a major loss.</div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class=""><br class=""></div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class="">Just because Swift is not garbage collected doesn’t mean
that you can’t safely unwind the stack and continue execution
somewhere. If “bad” developers would start using this as unwanted
exceptions, then it can be made inconvient somehow.</div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class=""><br class=""></div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class="">Think about a server that handles 1,000 requests per
minute - its going to happen evenutally, even despite testing, and
chances are that once it happens it will re-occur - and now the
server goes down every minute or even every few seconds and needs
an auto-restart loop.</div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class=""><br class=""></div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class="">If we’re going to be talking about “bad developers” as in
ones who might once code a bug with an optional or index out of
bounds exception, then that is going to be a very high standard and
result in a very mild adoption of server side Swift. Maybe it would
take off for a while, and then when people realize these things,
they will say “thats why everyone writes their server-side code in
Java/C#/PHP, etc” and Swift will be a thing for people who need
ultra-fast performance on a server.</div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class=""><br class=""></div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;margin:0px" class="">Its not really Apple’s business, and clearly you are
trying to replace only C++ and not Java/C#, but if you can add a
compiler mode with exceptions instead of fatalError(mesage:) calls,
that would contribute a lot to making web servers with Swift. Even
if you leak the entire call stack, it would still be better than
crashing an entire web serer.</div>
<br style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">
<div id="bloop_sign_1489343942528276992" class="bloop_sign" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">
</div>
<br style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px" class="">
<p class="airmail_on" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">
On March 6, 2017 at 9:47:03 PM, Austin Zheng (<a href="mailto:austinzheng@gmail.com" class="">austinzheng@gmail.com</a>)
wrote:</p>
<blockquote type="cite" class="clean_bq" style="font-family:Helvetica,Arial;font-size:13px;font-style:normal;font-variant-caps:normal;font-weight:normal;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">
<div class="">
<div class=""></div>
<div class="">
<div dir="ltr" class=""><span class="">Swift already is an
unmanaged language, and is far closer to C++ than Java. There is no
equivalent to the CLR or JVM and it is trivially easy to call into
C code or the unsafe APIs and do nearly anything that C can do with
regard to direct access to memory.</span>
<div class=""><span class=""><br class=""></span></div>
<div class=""><span class="">The force-unwrap operator was never
intended to model a Java-style runtime exception. Instead, it is an
assertion which indicates a programmer logic error. The preferred
way to handle an optional at runtime has always been to use the
conditional-unwrapping functionality the language offers. The
correct way to report errors at runtime that aren't due to
programmer error is through the do-try-catch mechanism. Pervasive,
unnecessary use of '!' is a project management and/or developer
competence issue, and not something the language should go out of
its way to fix.</span></div>
<div class=""><span class=""><br class=""></span></div>
<div class=""><span class="">Sugaring 'if let' for programmer
convenience is something on the commonly rejected proposals
list: <a href="https://github.com/apple/swift-evolution/blob/master/commonly_proposed.md" class="">https://github.com/apple/swift-evolution/blob/master/commonly_proposed.md</a></span></div>
<div class=""><span class=""><br class=""></span></div>
<div class=""><span class="">Regards,</span></div>
<div class=""><span class="">Austin</span></div>
<div class=""><span class=""><br class=""></span></div>
</div>
<div class="gmail_extra"><span class=""><br class=""></span>
<div class="gmail_quote"><span class="">On Mon, Mar 6, 2017 at 6:27
PM, Elijah Johnson via swift-evolution<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""></span>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<div style="word-wrap:break-word" class="">
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class="">Additionally, not discarding previous comments, one way
the language could be improved is by replacing (or rather
augmenting) optional binding with a faster syntax.</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class="">ex.</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class="">func test( name : String?, name2 :String? ){</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""> name! , name2! {</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class="">// inside this block, “name” and “name2” are
non-optional</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""> <span class="Apple-converted-space"> </span>} else {</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""> <span class="Apple-converted-space"> </span>// no forced unwrapping, just
optional else case</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""> }</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class="">}</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class="">Whereas the alternative (current optional binding),
requires a re-definition of variables and an additional “if”
operator. Besides the extra characters involved in typing and
reading it, usually variables have specific names that the user
does not want to augument.</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class="">
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class="">func test( name : String?, name2 :String?
){</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""> <span class="Apple-converted-space"> </span>if let nameUnwrapped = name ,
let name2Unwrapped = name2 {</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""> <span class="Apple-converted-space"> </span>} else {</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""> }</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class="">}</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class="">
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class="">func test( name : String?, name2 :String?
){</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""> <span class="Apple-converted-space"> </span>guard let nameUnwrapped = name
, let name2Unwrapped = name2 else {</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""> <span class="Apple-converted-space"> </span>}</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class="">}</div>
</div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="margin:0px" class="">The fact that we don’t need a
“nameUnwrapped” variable (which is unsightly and requires
refractoring) is one thing that still makes forced unwrapping still
very much a necessary or common part of Swift coding, even where it
could be replaced with optional binding.</div>
</div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><br class=""></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><br class=""></div>
<br class="">
<div id="m_2492479024697317942bloop_sign_1488852857050308864" class="m_2492479024697317942bloop_sign"></div>
<br class="">
<p class="m_2492479024697317942airmail_on">On March 6, 2017 at
7:20:40 PM, Elijah Johnson (<a href="mailto:ejrx7753@gmail.com" target="_blank" class="">ejrx7753@gmail.com</a>) wrote:</p>
<blockquote type="cite" class="m_2492479024697317942clean_bq">
<div style="word-wrap:break-word" class="">
<div class="">
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">Hi,</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class=""><br class=""></span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">I’ve been recently considering Swift on the
server-side, and there came up the question, “what happens when a
null optional is forcibly unwrapped?” and the answer was clearly
that not only would the request crash, but the entire server would
also crash, since the server itself is/would be also written in
Swift.</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class=""><br class=""></span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">I think that this highlights serveral
weaknesses in Swift’s “null safety” attempts. The first is that
there needs to be a way to isolate blocks of code so that a “null
pointer exception” does not crash the system. I think it is fair to
say, in the language of Java, that these are really “runtime
exceptions” and for some reason are being treated as segmentation
faults would be in C/C++. In my opinion, the existence of these
things has the ability to bring Swift down below Java and closer to
an unamanged language. Not really sure why it would ever be
desireable, but in terms of server-side programming, it is
definitely a serious issue.</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class=""><br class=""></span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">Secondly, Swift’s “null safety” is really
completely undermined by these “force-unwrap” errors. I agree with
the usage of new language features like guard, optional binding,
etc to remove a null value, but I see this force-unwrap as
extremely pervasive for a lot of reasons:</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class=""><br class=""></span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">1. When porting code from a C style
language to Swift, force-unwrap is needed to make the code work
without refractoring.</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">2. XCode itself reccomends this operator
and when it is used to satisfy a requirement, then it can be left
in the code</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">3. Some styles of coding just can’t work
without force-unwrap.</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class=""><br class=""></span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">I don’t think the logic of making the
consequences extreme for making a mistake are a rational for making
better coders. In fact, I personally see the “force-unwrap”
operator having very great potential usage as a deliberate
assertion exception - the programmer demands that a certain value
be non-null for execution to continue, only there should be a
proper scope and context where these exceptions can propogate to.
On debug modes, one might want it to pause on the line, but for
other uses, it should be caught IMO - on regular code by the user,
and inside dispatch blocks by the queue itself. For a multithreaded
app or server to exit, the user should have to explicitly write
exit(0), isn’t this the goal of a managed language? Maybe in some
cases, Apple will want the program to crash, but if Swift is given
an audience not just with Apple hardware, then it should have more
flexibility IMO.</span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class=""><br class=""></span></div>
<div id="m_2492479024697317942bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;margin:0px" class=""><span class="">Elijah</span></div>
<div id="m_2492479024697317942bloop_sign_1488843525920942080" class="m_2492479024697317942bloop_sign"></div>
</div>
</div>
</blockquote>
</div>
<br class="">
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