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.error { color:#AA0000; }</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class="bloop_markdown"><p>Sorry, I couldn’t follow every thread. I simply couldn’t get that fact from the given context of the first post by Anton. :) Just forget everything I mentioned about typealias, because it was based on the assumption of an error list.</p>
<p>Anyways +1 for typed throws. The syntax <code>throws(T)</code> and <code>rethrows(T)</code> is fine by me.</p>
<p></p></div><div class="bloop_original_html"><style>body{font-family:Helvetica,Arial;font-size:13px}</style><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> <br> <div id="bloop_sign_1487360769079386880" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">-- <br>Adrian Zubarev<br>Sent with Airmail</div></div> <br><p class="airmail_on">Am 17. Februar 2017 um 20:45:55, Matthew Johnson (<a href="mailto:matthew@anandabits.com">matthew@anandabits.com</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div></div><div>
<title></title>
<br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Feb 17, 2017, at 1:42 PM, Adrian Zubarev 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="">
<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; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; margin: 0px;" class="">So the typed throws are going to be limited to a single
error type, is that the direction we're heading to?</div>
</div>
</blockquote>
<div><br class=""></div>
Yes, this topic was discussed thoroughly last year.</div>
<div><br class="">
<blockquote type="cite" class="">
<div class=""><br style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: 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;" class="">
<div id="bloop_sign_1487360439950413824" class="bloop_sign" style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: 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;">
<div style="font-family: helvetica, arial; font-size: 13px;" class="">-- <br class="">
Adrian Zubarev<br class="">
Sent with Airmail</div>
</div>
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<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; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">
Am 17. Februar 2017 um 20:39:12, Anton Zhilin (<a href="mailto:antonyzhilin@gmail.com" class="">antonyzhilin@gmail.com</a>) schrieb:</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; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;">
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<div class="markdown-here-wrapper">
<p style="margin: 0px 0px 1.2em !important;" class=""><span class="">In this case, you’d better create a new error type, which
includes all the cases of those errors:</span></p>
<pre style="font-family: Consolas, Inconsolata, Courier, monospace; font-size: 1em; line-height: 1.2em; margin: 1.2em 0px;" class=""><span class=""><code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace; margin: 0px 0.15em; background-color: rgb(248, 248, 248); white-space: pre; overflow: auto; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; border: 1px solid rgb(204, 204, 204); padding: 0.5em 0.7em; display: block !important;" class="">// FileNotFoundError and WrongFormat are Error-s
struct PreferencesError : Error {
init(_: FileNotFoundError)
init(_: WrongFormat)
// ...
}
func readPreferences() throws(PreferencesError)
</code></span></pre>
<p style="margin: 0px 0px 1.2em !important;" class=""><span class="">In the most “lazy” case, you’d just create an enum of those
two:</span></p>
<pre style="font-family: Consolas, Inconsolata, Courier, monospace; font-size: 1em; line-height: 1.2em; margin: 1.2em 0px;" class=""><span class=""><code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace; margin: 0px 0.15em; background-color: rgb(248, 248, 248); white-space: pre; overflow: auto; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; border: 1px solid rgb(204, 204, 204); padding: 0.5em 0.7em; display: block !important;" class="">enum PreferencesError : Error {
case fileNotFound(FileNotFoundError)
case wrongFormat(WrongFormatError)
}
</code></span></pre>
<p style="margin: 0px 0px 1.2em !important;" class=""><span class="">Better yet, you should analyze, which cases are meaningful for
user of<span class="Apple-converted-space"> </span><code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace; margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; display: inline;" class="">readPreferences</code>, and present them with appropriate
interface. You may want to crash on those cases of initial error
types, with which you can’t do anything on the level of abstraction
of<span class="Apple-converted-space"> </span><code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace; margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; display: inline;" class="">readPreferences</code>. Some of the others will be merged
or renamed.</span></p>
<p style="margin: 0px 0px 1.2em !important;" class="">With proper
error types, a single type in<span class="Apple-converted-space"> </span><code style="font-size: 0.85em; font-family: Consolas, Inconsolata, Courier, monospace; margin: 0px 0.15em; padding: 0px 0.3em; white-space: pre-wrap; border: 1px solid rgb(234, 234, 234); background-color: rgb(248, 248, 248); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; display: inline;" class="">throws</code><span class="Apple-converted-space"> </span>clause is enough, without sum
types.</p>
<p style="margin: 0px 0px 1.2em !important;" class="">2017-02-17
22:22 GMT+03:00 Adrian Zubarev via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>>:</p>
<div style="margin: 0px 0px 1.2em !important;" class=""><br class="webkit-block-placeholder"></div>
<div class="markdown-here-exclude">
<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 class="m_7383326189739117365bloop_markdown">
<p class="">Sure thing, but that’s not what I was asking about.
Kevin made a protocol that conforms to<span class="Apple-converted-space"> </span><code class="">Error</code><span class="Apple-converted-space"> </span>where all the his enums
conformed to<span class="Apple-converted-space"> </span><code class="">MyError</code><span class="Apple-converted-space"> </span>protocol. That way we’re
losing all enum cases and are not really a step further as
before.</p>
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