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<h1 class="header-title">A Rustic Re-Podcasting Server (Part 1)</h1>
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<p class="header-date"> <a href="https://bspeice.github.io/author/bradlee-speice.html">Bradlee Speice</a>, Sat 22 October 2016, <a href="https://bspeice.github.io/category/blog.html">Blog</a></p>
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<p class="header-date"> <a href="/author/bradlee-speice.html">Bradlee Speice</a>, Sat 22 October 2016, <a href="/category/blog.html">Blog</a></p>
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<a href="https://bspeice.github.io/tag/nutone.html">nutone</a>, <a href="https://bspeice.github.io/tag/rust.html">Rust</a> </p>
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<a href="/tag/nutone.html">nutone</a>, <a href="/tag/rust.html">Rust</a> </p>
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@ -128,15 +115,15 @@ on some bad cases, <code>str <-> bytes</code> specifically), but Rust is h
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should be incredibly simple: All I want is to echo back
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<code>Didn't find URL: <url></code>. Shouldn't be that hard right? In Python I'd just do
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something like:</p>
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<div class="highlight"><pre><span class="k">def</span> <span class="nf">echo_handler</span><span class="p">(</span><span class="n">request</span><span class="p">):</span>
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<div class="highlight"><pre><span></span><span class="k">def</span> <span class="nf">echo_handler</span><span class="p">(</span><span class="n">request</span><span class="p">):</span>
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<span class="k">return</span> <span class="s2">"You're visiting: {}"</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">request</span><span class="o">.</span><span class="n">uri</span><span class="p">)</span>
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</pre></div>
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<p>And we'd call it a day. Rust isn't so simple. Let's start with the trivial
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examples people post online:</p>
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<div class="highlight"><pre><span class="k">fn</span><span class="w"> </span><span class="n">hello_world</span><span class="p">(</span><span class="n">req</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
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<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span><span class="o">::</span><span class="n">with</span><span class="p">((</span><span class="n">status</span><span class="o">::</span><span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="s">"You found the server!"</span><span class="p">)))</span><span class="w"></span>
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<div class="highlight"><pre><span></span><span class="k">fn</span> <span class="nf">hello_world</span><span class="p">(</span><span class="n">req</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span>-> <span class="nc">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
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<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span>::<span class="n">with</span><span class="p">((</span><span class="n">status</span>::<span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="s">"You found the server!"</span><span class="p">)))</span><span class="w"></span>
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<span class="p">}</span><span class="w"></span>
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</pre></div>
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@ -145,22 +132,22 @@ examples people post online:</p>
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version! All we need to do is just send back a string of some form. So, we
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look up the documentation for <a href="http://ironframework.io/doc/iron/request/struct.Request.html"><code>Request</code></a> and see a <code>url</code> field that will contain
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what we want. Let's try the first iteration:</p>
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<div class="highlight"><pre><span class="k">fn</span><span class="w"> </span><span class="n">hello_world</span><span class="p">(</span><span class="n">req</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
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<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span><span class="o">::</span><span class="n">with</span><span class="p">((</span><span class="n">status</span><span class="o">::</span><span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="s">"You found the URL: "</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">req</span><span class="p">.</span><span class="n">url</span><span class="p">)))</span><span class="w"></span>
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<div class="highlight"><pre><span></span><span class="k">fn</span> <span class="nf">hello_world</span><span class="p">(</span><span class="n">req</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span>-> <span class="nc">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
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||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span>::<span class="n">with</span><span class="p">((</span><span class="n">status</span>::<span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="s">"You found the URL: "</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">req</span><span class="p">.</span><span class="n">url</span><span class="p">)))</span><span class="w"></span>
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<span class="p">}</span><span class="w"></span>
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</pre></div>
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<p>Which yields the error:</p>
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<div class="highlight"><pre>error[E0369]: binary operation `+` cannot be applied to type `&'static str`
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<div class="highlight"><pre><span></span>error[E0369]: binary operation `+` cannot be applied to type `&'static str`
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</pre></div>
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<p>OK, what's going on here? Time to start Googling for <a href="https://www.google.com/#q=concatenate+strings+in+rust">"concatenate strings in Rust"</a>. That's what we
|
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want to do right? Concatenate a static string and the URL.</p>
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||||
<p>After Googling, we come across a helpful <a href="https://doc.rust-lang.org/std/macro.concat!.html"><code>concat!</code></a> macro that looks really nice! Let's try that one:</p>
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<div class="highlight"><pre><span class="k">fn</span><span class="w"> </span><span class="n">hello_world</span><span class="p">(</span><span class="n">req</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span><span class="o">::</span><span class="n">with</span><span class="p">((</span><span class="n">status</span><span class="o">::</span><span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="n">concat</span><span class="o">!</span><span class="p">(</span><span class="s">"You found the URL: "</span><span class="p">,</span><span class="w"> </span><span class="n">req</span><span class="p">.</span><span class="n">url</span><span class="p">))))</span><span class="w"></span>
|
||||
<div class="highlight"><pre><span></span><span class="k">fn</span> <span class="nf">hello_world</span><span class="p">(</span><span class="n">req</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span>-> <span class="nc">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span>::<span class="n">with</span><span class="p">((</span><span class="n">status</span>::<span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="n">concat</span><span class="o">!</span><span class="p">(</span><span class="s">"You found the URL: "</span><span class="p">,</span><span class="w"> </span><span class="n">req</span><span class="p">.</span><span class="n">url</span><span class="p">))))</span><span class="w"></span>
|
||||
<span class="p">}</span><span class="w"></span>
|
||||
</pre></div>
|
||||
|
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@ -172,8 +159,8 @@ at compile time what <code>req.url</code> is. Which, in my outsider opinion, is
|
||||
strange. <code>println!</code> and <code>format!</code>, etc., all handle values they don't know at
|
||||
compile time. Why can't <code>concat!</code>? By any means, we need a new plan of attack.
|
||||
How about we try formatting strings?</p>
|
||||
<div class="highlight"><pre><span class="k">fn</span><span class="w"> </span><span class="n">hello_world</span><span class="p">(</span><span class="n">req</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span><span class="o">::</span><span class="n">with</span><span class="p">((</span><span class="n">status</span><span class="o">::</span><span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="n">format</span><span class="o">!</span><span class="p">(</span><span class="s">"You found the URL: {}"</span><span class="p">,</span><span class="w"> </span><span class="n">req</span><span class="p">.</span><span class="n">url</span><span class="p">))))</span><span class="w"></span>
|
||||
<div class="highlight"><pre><span></span><span class="k">fn</span> <span class="nf">hello_world</span><span class="p">(</span><span class="n">req</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span>-> <span class="nc">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span>::<span class="n">with</span><span class="p">((</span><span class="n">status</span>::<span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="n">format</span><span class="o">!</span><span class="p">(</span><span class="s">"You found the URL: {}"</span><span class="p">,</span><span class="w"> </span><span class="n">req</span><span class="p">.</span><span class="n">url</span><span class="p">))))</span><span class="w"></span>
|
||||
<span class="p">}</span><span class="w"></span>
|
||||
</pre></div>
|
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|
||||
@ -204,9 +191,9 @@ working on things that are a bit more complex?</p>
|
||||
<p>We're going to cover that here. Our first try: creating a function which returns
|
||||
other functions. This is a principle called <a href="http://stackoverflow.com/a/36321/1454178">currying</a>. We set up a function that allows us to keep some data in scope
|
||||
for another function to come later.</p>
|
||||
<div class="highlight"><pre><span class="k">fn</span><span class="w"> </span><span class="n">build_handler</span><span class="p">(</span><span class="n">message</span><span class="o">:</span><span class="w"> </span><span class="nb">String</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="nb">Fn</span><span class="p">(</span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="n">move</span><span class="w"> </span><span class="o">|</span><span class="n">_</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="o">|</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span><span class="o">::</span><span class="n">with</span><span class="p">((</span><span class="n">status</span><span class="o">::</span><span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="n">message</span><span class="p">)))</span><span class="w"></span>
|
||||
<div class="highlight"><pre><span></span><span class="k">fn</span> <span class="nf">build_handler</span><span class="p">(</span><span class="n">message</span>: <span class="nb">String</span><span class="p">)</span><span class="w"> </span>-> <span class="nb">Fn</span><span class="p">(</span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span>-> <span class="nc">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="k">move</span><span class="w"> </span><span class="o">|</span><span class="n">_</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="o">|</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span>::<span class="n">with</span><span class="p">((</span><span class="n">status</span>::<span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="n">message</span><span class="p">)))</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||||
<span class="p">}</span><span class="w"></span>
|
||||
</pre></div>
|
||||
@ -215,7 +202,7 @@ for another function to come later.</p>
|
||||
<p>We've simply set up a function that returns another anonymous function with the
|
||||
<code>message</code> parameter scoped in. If you compile this, you get not 1, not 2, but 5
|
||||
new errors. 4 of them are the same though:</p>
|
||||
<div class="highlight"><pre>error[E0277]: the trait bound `for<'r, 'r, 'r> std::ops::Fn(&'r mut iron::Request<'r, 'r>) -> std::result::Result<iron::Response, iron::IronError> + 'static: std::marker::Sized` is not satisfied
|
||||
<div class="highlight"><pre><span></span>error[E0277]: the trait bound `for<'r, 'r, 'r> std::ops::Fn(&'r mut iron::Request<'r, 'r>) -> std::result::Result<iron::Response, iron::IronError> + 'static: std::marker::Sized` is not satisfied
|
||||
</pre></div>
|
||||
|
||||
|
||||
@ -243,19 +230,19 @@ we've been working with so far.</p>
|
||||
<p>The principle is that we need to define a new <code>struct</code> to hold our data, then
|
||||
implement that <code>handle()</code> method to return the result. Something that looks
|
||||
like this might do:</p>
|
||||
<div class="highlight"><pre><span class="k">struct</span><span class="w"> </span><span class="n">EchoHandler</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="n">message</span><span class="o">:</span><span class="w"> </span><span class="nb">String</span><span class="w"></span>
|
||||
<div class="highlight"><pre><span></span><span class="k">struct</span> <span class="nc">EchoHandler</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="n">message</span>: <span class="nb">String</span>
|
||||
<span class="p">}</span><span class="w"></span>
|
||||
|
||||
<span class="k">impl</span><span class="w"> </span><span class="n">Handler</span><span class="w"> </span><span class="k">for</span><span class="w"> </span><span class="n">EchoHandler</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="k">fn</span><span class="w"> </span><span class="n">handle</span><span class="p">(</span><span class="o">&</span><span class="bp">self</span><span class="p">,</span><span class="w"> </span><span class="n">_</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span><span class="o">-></span><span class="w"> </span><span class="n">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span><span class="o">::</span><span class="n">with</span><span class="p">((</span><span class="n">status</span><span class="o">::</span><span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="bp">self</span><span class="p">.</span><span class="n">message</span><span class="p">)))</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="k">fn</span> <span class="nf">handle</span><span class="p">(</span><span class="o">&</span><span class="bp">self</span><span class="p">,</span><span class="w"> </span><span class="n">_</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="p">)</span><span class="w"> </span>-> <span class="nc">IronResult</span><span class="o"><</span><span class="n">Response</span><span class="o">></span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span>::<span class="n">with</span><span class="p">((</span><span class="n">status</span>::<span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="bp">self</span><span class="p">.</span><span class="n">message</span><span class="p">)))</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="p">}</span><span class="w"></span>
|
||||
<span class="p">}</span><span class="w"></span>
|
||||
|
||||
<span class="c1">// Later in the code when we set up the router...</span>
|
||||
<span class="kd">let</span><span class="w"> </span><span class="n">echo</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">EchoHandler</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="n">message</span><span class="o">:</span><span class="w"> </span><span class="s">"Is it working yet?"</span><span class="w"></span>
|
||||
<span class="w"> </span><span class="n">message</span>: <span class="s">"Is it working yet?"</span><span class="w"></span>
|
||||
<span class="p">}</span><span class="w"></span>
|
||||
<span class="n">router</span><span class="p">.</span><span class="n">get</span><span class="p">(</span><span class="s">"/"</span><span class="p">,</span><span class="w"> </span><span class="n">echo</span><span class="p">.</span><span class="n">handle</span><span class="p">,</span><span class="w"> </span><span class="s">"index"</span><span class="p">);</span><span class="w"></span>
|
||||
</pre></div>
|
||||
@ -264,38 +251,38 @@ like this might do:</p>
|
||||
<p>We attempt to build a struct, and give its <code>handle</code> method off to the router
|
||||
so the router knows what to do.</p>
|
||||
<p>You guessed it, more errors:</p>
|
||||
<div class="highlight"><pre><span class="n">error</span><span class="o">:</span> <span class="n">attempted</span> <span class="n">to</span> <span class="n">take</span> <span class="n">value</span> <span class="n">of</span> <span class="n">method</span> <span class="err">`</span><span class="n">handle</span><span class="err">`</span> <span class="n">on</span> <span class="n">type</span> <span class="err">`</span><span class="n">EchoHandler</span><span class="err">`</span>
|
||||
<div class="highlight"><pre><span></span><span class="n">error</span><span class="o">:</span> <span class="n">attempted</span> <span class="n">to</span> <span class="n">take</span> <span class="n">value</span> <span class="n">of</span> <span class="n">method</span> <span class="err">`</span><span class="n">handle</span><span class="err">`</span> <span class="n">on</span> <span class="n">type</span> <span class="err">`</span><span class="n">EchoHandler</span><span class="err">`</span>
|
||||
</pre></div>
|
||||
|
||||
|
||||
<p>Now, the Rust compiler is actually a really nice fellow, and offers us help:</p>
|
||||
<div class="highlight"><pre><span class="n">help</span><span class="o">:</span> <span class="n">maybe</span> <span class="n">a</span> <span class="err">`</span><span class="o">()</span><span class="err">`</span> <span class="n">to</span> <span class="n">call</span> <span class="n">it</span> <span class="k">is</span> <span class="n">missing</span><span class="o">?</span> <span class="n">If</span> <span class="n">not</span><span class="o">,</span> <span class="k">try</span> <span class="n">an</span> <span class="n">anonymous</span> <span class="kd">function</span>
|
||||
<div class="highlight"><pre><span></span><span class="n">help</span><span class="o">:</span> <span class="n">maybe</span> <span class="n">a</span> <span class="err">`</span><span class="o">()</span><span class="err">`</span> <span class="n">to</span> <span class="n">call</span> <span class="n">it</span> <span class="k">is</span> <span class="n">missing</span><span class="o">?</span> <span class="n">If</span> <span class="n">not</span><span class="o">,</span> <span class="k">try</span> <span class="n">an</span> <span class="n">anonymous</span> <span class="kd">function</span>
|
||||
</pre></div>
|
||||
|
||||
|
||||
<p>We definitely don't want to call that function, so maybe try an anonymous
|
||||
function as it recommends?</p>
|
||||
<div class="highlight"><pre><span class="n">router</span><span class="p">.</span><span class="n">get</span><span class="p">(</span><span class="s">"/"</span><span class="p">,</span><span class="w"> </span><span class="o">|</span><span class="n">req</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="o">|</span><span class="w"> </span><span class="n">echo</span><span class="p">.</span><span class="n">handle</span><span class="p">(</span><span class="n">req</span><span class="p">),</span><span class="w"> </span><span class="s">"index"</span><span class="p">);</span><span class="w"></span>
|
||||
<div class="highlight"><pre><span></span><span class="n">router</span><span class="p">.</span><span class="n">get</span><span class="p">(</span><span class="s">"/"</span><span class="p">,</span><span class="w"> </span><span class="o">|</span><span class="n">req</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="o">|</span><span class="w"> </span><span class="n">echo</span><span class="p">.</span><span class="n">handle</span><span class="p">(</span><span class="n">req</span><span class="p">),</span><span class="w"> </span><span class="s">"index"</span><span class="p">);</span><span class="w"></span>
|
||||
</pre></div>
|
||||
|
||||
|
||||
<p>Another error:</p>
|
||||
<div class="highlight"><pre>error[E0373]: closure may outlive the current function, but it borrows `echo`, which is owned by the current function
|
||||
<div class="highlight"><pre><span></span>error[E0373]: closure may outlive the current function, but it borrows `echo`, which is owned by the current function
|
||||
</pre></div>
|
||||
|
||||
|
||||
<p>Another helpful message:</p>
|
||||
<div class="highlight"><pre><span class="n">help</span><span class="o">:</span> <span class="n">to</span> <span class="n">force</span> <span class="n">the</span> <span class="n">closure</span> <span class="n">to</span> <span class="n">take</span> <span class="n">ownership</span> <span class="n">of</span> <span class="err">`</span><span class="n">echo</span><span class="err">`</span> <span class="o">(</span><span class="n">and</span> <span class="n">any</span> <span class="n">other</span> <span class="n">referenced</span> <span class="n">variables</span><span class="o">),</span> <span class="n">use</span> <span class="n">the</span> <span class="err">`</span><span class="n">move</span><span class="err">`</span> <span class="n">keyword</span>
|
||||
<div class="highlight"><pre><span></span><span class="n">help</span><span class="o">:</span> <span class="n">to</span> <span class="n">force</span> <span class="n">the</span> <span class="n">closure</span> <span class="n">to</span> <span class="n">take</span> <span class="n">ownership</span> <span class="n">of</span> <span class="err">`</span><span class="n">echo</span><span class="err">`</span> <span class="o">(</span><span class="n">and</span> <span class="n">any</span> <span class="n">other</span> <span class="n">referenced</span> <span class="n">variables</span><span class="o">),</span> <span class="n">use</span> <span class="n">the</span> <span class="err">`</span><span class="n">move</span><span class="err">`</span> <span class="n">keyword</span>
|
||||
</pre></div>
|
||||
|
||||
|
||||
<p>We're getting closer though! Let's implement this change:</p>
|
||||
<div class="highlight"><pre><span class="n">router</span><span class="p">.</span><span class="n">get</span><span class="p">(</span><span class="s">"/"</span><span class="p">,</span><span class="w"> </span><span class="n">move</span><span class="w"> </span><span class="o">|</span><span class="n">req</span><span class="o">:</span><span class="w"> </span><span class="o">&</span><span class="k">mut</span><span class="w"> </span><span class="n">Request</span><span class="o">|</span><span class="w"> </span><span class="n">echo</span><span class="p">.</span><span class="n">handle</span><span class="p">(</span><span class="n">req</span><span class="p">),</span><span class="w"> </span><span class="s">"index"</span><span class="p">);</span><span class="w"></span>
|
||||
<div class="highlight"><pre><span></span><span class="n">router</span><span class="p">.</span><span class="n">get</span><span class="p">(</span><span class="s">"/"</span><span class="p">,</span><span class="w"> </span><span class="k">move</span><span class="w"> </span><span class="o">|</span><span class="n">req</span>: <span class="kp">&</span><span class="nc">mut</span><span class="w"> </span><span class="n">Request</span><span class="o">|</span><span class="w"> </span><span class="n">echo</span><span class="p">.</span><span class="n">handle</span><span class="p">(</span><span class="n">req</span><span class="p">),</span><span class="w"> </span><span class="s">"index"</span><span class="p">);</span><span class="w"></span>
|
||||
</pre></div>
|
||||
|
||||
|
||||
<p>And here's where things get strange:</p>
|
||||
<div class="highlight"><pre>error[E0507]: cannot move out of borrowed content
|
||||
<div class="highlight"><pre><span></span>error[E0507]: cannot move out of borrowed content
|
||||
--> src/main.rs:18:40
|
||||
|
|
||||
18 | Ok(Response::with((status::Ok, self.message)))
|
||||
@ -320,7 +307,7 @@ instead of transferring ownership</li>
|
||||
audience out. Because <code>iron</code> won't accept a reference, we are forced into the
|
||||
second option: making a copy. To do so, we just need to change the function
|
||||
to look like this:</p>
|
||||
<div class="highlight"><pre><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span><span class="o">::</span><span class="n">with</span><span class="p">((</span><span class="n">status</span><span class="o">::</span><span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="bp">self</span><span class="p">.</span><span class="n">message</span><span class="p">.</span><span class="n">clone</span><span class="p">())))</span><span class="w"></span>
|
||||
<div class="highlight"><pre><span></span><span class="nb">Ok</span><span class="p">(</span><span class="n">Response</span>::<span class="n">with</span><span class="p">((</span><span class="n">status</span>::<span class="nb">Ok</span><span class="p">,</span><span class="w"> </span><span class="bp">self</span><span class="p">.</span><span class="n">message</span><span class="p">.</span><span class="n">clone</span><span class="p">())))</span><span class="w"></span>
|
||||
</pre></div>
|
||||
|
||||
|
||||
@ -356,20 +343,6 @@ incredibly precise about how I use it.</p>
|
||||
going to take me a lot longer to do this than I originally thought.</p>
|
||||
|
||||
|
||||
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||||
@ -381,7 +354,6 @@ going to take me a lot longer to do this than I originally thought.</p>
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Reference in New Issue
Block a user