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.send { color:#77bb77; }
.server { color:#7799bb; }
.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>Don’t get me wrong, in my case default values with an optional will work just fine, but I don’t see how default values are better on associated types than:</p>
<pre><code class="swift">// default values
enum Something {
case a(String, Int? = nil, Int? = nil)
}
// vs.
enum Something {
case a(String)
case a(String, Int)
case a(String, Int, Int)
}
</code></pre>
<p>When the enum is public, do you want the user to check for all the optionals. This could be really pesky, if you ask me.</p>
<pre><code class="swift">if case a(let stringValue, .some(let firstInt), .some(let secondInt)) = … {}
// vs.
if case a(let stringValue, let firstInt, let secondInt) = … {}
</code></pre>
<p>How about this short example? How would you design an enum with default values? The idea here is to use the same enum case for number literals. Maybe the design of the API does not want something like <code>case int(Int)</code> and <code>case double(Double)</code> for any reasons.</p>
<pre><code class="swift">enum Value {
case string(String)
case number(Int)
case number(Double)
}
let intCase: Value = .number(1)
let doubleCase: Value = .number(2.0)
</code></pre>
<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_1480438884994848000" 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 29. November 2016 um 17:45:07, Tony Allevato (<a href="mailto:allevato@google.com">allevato@google.com</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div><div></div><div>
<title></title>
<div dir="ltr"><br>
<br>
<div class="gmail_quote">
<div dir="ltr">On Tue, Nov 29, 2016 at 8:35 AM Adrian Zubarev
<<a href="mailto:adrian.zubarev@devandartist.com">adrian.zubarev@devandartist.com</a>>
wrote:<br></div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word" class="gmail_msg">
<div class="m_-5836122890542383372bloop_markdown gmail_msg">
<p class="gmail_msg">If we’re talking about non optional values
here, then I don’t produce a possible expensive copy of my
associated values (sure it depends on the type, COW etc.), but
that’s my main point for excluding the the associated values.</p>
</div>
</div>
</blockquote>
<div>Does matching against _ cause a copy to be made? I wouldn't
expect it to since it can never be used. If it does, I'd argue
that's a bug.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word" class="gmail_msg">
<div class="m_-5836122890542383372bloop_markdown gmail_msg">
<p class="gmail_msg">Somewhere in my code I also have a semi schema
subscript which evaluates the enum case like this:</p>
<pre class="gmail_msg"><code class="m_-5836122890542383372swift gmail_msg">if case .double = $0 { return true } else { return false }
</code></pre>
<p class="gmail_msg">There is just no better way for this check. I
wish I could write something like <code class="gmail_msg">return
.double ~= $0</code> there.</p>
</div>
</div>
</blockquote>
<div>We agree on this—I've had situations where I all I wanted to
know was whether an enum value matched a particular case, and a
Boolean case expression would be fantastic.</div>
<div><br></div>
<div>
<div>Re: your earlier message, I'm trying to understand why you
want to avoid wrapping your types in optionals when, if you can
express both the presence and absence of them in an overloaded
case, that effectively means they *are* optional? Is there a
particular problem with Optional<T> that you're trying to
avoid? If you're already pattern matching to detect the enum case,
unwrapping the optional at the same time is no more difficult than
if it were non-optional.</div>
<div><br></div>
<div>I'm not convinced that overloading enum cases is something
that should be supported, but I'm about 90% on supporting default
values. So I'm trying to understand why you want this specific
feature for your specific problem, and how it could apply
elsewhere.<br></div>
<br class="inbox-inbox-Apple-interchange-newline"></div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word" class="gmail_msg">
<div class="m_-5836122890542383372bloop_markdown gmail_msg">
<p class="gmail_msg"></p>
</div>
<div class="m_-5836122890542383372bloop_original_html gmail_msg">
</div>
</div>
<div style="word-wrap:break-word" class="gmail_msg">
<div class="m_-5836122890542383372bloop_original_html gmail_msg">
<div id="m_-5836122890542383372bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px;color:rgba(0,0,0,1.0);margin:0px;line-height:auto" class="gmail_msg"><br class="gmail_msg"></div>
<br class="gmail_msg">
<div id="m_-5836122890542383372bloop_sign_1480436917070613760" class="m_-5836122890542383372bloop_sign gmail_msg">
<div style="font-family:helvetica,arial;font-size:13px" class="gmail_msg">-- <br class="gmail_msg">
Adrian Zubarev<br class="gmail_msg">
Sent with Airmail</div>
</div>
<br class="gmail_msg"></div>
</div>
<div style="word-wrap:break-word" class="gmail_msg">
<div class="m_-5836122890542383372bloop_original_html gmail_msg">
<p class="m_-5836122890542383372airmail_on gmail_msg">Am 29.
November 2016 um 17:19:16, Tony Allevato (<a href="mailto:allevato@google.com" class="gmail_msg" target="_blank">allevato@google.com</a>) schrieb:</p>
</div>
</div>
<div style="word-wrap:break-word" class="gmail_msg">
<div class="m_-5836122890542383372bloop_original_html gmail_msg">
<blockquote type="cite" class="m_-5836122890542383372clean_bq gmail_msg">
<div class="gmail_msg"><span class="gmail_msg"><span style="color:rgb(0,0,0);font-family:'helvetica Neue',helvetica;font-size:14px;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;background-color:rgb(255,255,255);display:inline!important;float:none" class="gmail_msg">I suppose I'm not seeing why it's important to
exclude the associated values from pattern matching. What do you
gain except saving a few characters?</span></span></div>
</blockquote>
</div>
</div>
</blockquote>
</div>
</div>
</div></div></span></blockquote></div><div class="bloop_markdown"><p></p></div></body></html>