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@ -181,7 +181,7 @@ fn main() {
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}
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}
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</code></pre></pre>
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</code></pre></pre>
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<p>After <code>takes_a_string</code> takes <code>user_name</code>, you can't use it anymore. Here that is no problem: you can just give it <code>user_name.clone()</code>. But sometimes a variable is part of a struct, and maybe you can't clone the struct. Or maybe the <code>String</code> is really long and you don't want to clone it. These are some reasons for <code>Rc</code>, which lets you have more than one owner. An <code>Rc</code> is like a good office worker: <code>Rc</code> writes down who has ownership, and how many. Then once the number of owners goes down to 0, the variable can disappear.</p>
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<p>After <code>takes_a_string</code> takes <code>user_name</code>, you can't use it anymore. Here that is no problem: you can just give it <code>user_name.clone()</code>. But sometimes a variable is part of a struct, and maybe you can't clone the struct. Or maybe the <code>String</code> is really long and you don't want to clone it. These are some reasons for <code>Rc</code>, which lets you have more than one owner. An <code>Rc</code> is like a good office worker: <code>Rc</code> writes down who has ownership, and how many. Then once the number of owners goes down to 0, the variable can disappear.</p>
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<p>Here's how you use an <code>Rc</code>. First imagine two structs: one called <code>City</code>, and another called <code>Cities</code>. <code>City</code> has information for one city, and <code>Cities</code> puts all the cities together in <code>Vec</code>s.</p>
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<p>Here's how you use an <code>Rc</code>. First imagine two structs: one called <code>City</code>, and another called <code>CityData</code>. <code>City</code> has information for one city, and <code>CityData</code> puts all the cities together in <code>Vec</code>s.</p>
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<pre><pre class="playground"><code class="language-rust">#[derive(Debug)]
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<pre><pre class="playground"><code class="language-rust">#[derive(Debug)]
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struct City {
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struct City {
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name: String,
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name: String,
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@ -240,7 +240,7 @@ struct City {
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}
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}
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#[derive(Debug)]
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#[derive(Debug)]
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struct Cities {
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struct CityData {
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names: Vec<String>,
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names: Vec<String>,
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histories: Vec<Rc<String>>,
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histories: Vec<Rc<String>>,
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}
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}
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@ -6590,7 +6590,7 @@ fn main() {
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}
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}
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</code></pre></pre>
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</code></pre></pre>
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<p>After <code>takes_a_string</code> takes <code>user_name</code>, you can't use it anymore. Here that is no problem: you can just give it <code>user_name.clone()</code>. But sometimes a variable is part of a struct, and maybe you can't clone the struct. Or maybe the <code>String</code> is really long and you don't want to clone it. These are some reasons for <code>Rc</code>, which lets you have more than one owner. An <code>Rc</code> is like a good office worker: <code>Rc</code> writes down who has ownership, and how many. Then once the number of owners goes down to 0, the variable can disappear.</p>
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<p>After <code>takes_a_string</code> takes <code>user_name</code>, you can't use it anymore. Here that is no problem: you can just give it <code>user_name.clone()</code>. But sometimes a variable is part of a struct, and maybe you can't clone the struct. Or maybe the <code>String</code> is really long and you don't want to clone it. These are some reasons for <code>Rc</code>, which lets you have more than one owner. An <code>Rc</code> is like a good office worker: <code>Rc</code> writes down who has ownership, and how many. Then once the number of owners goes down to 0, the variable can disappear.</p>
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<p>Here's how you use an <code>Rc</code>. First imagine two structs: one called <code>City</code>, and another called <code>Cities</code>. <code>City</code> has information for one city, and <code>Cities</code> puts all the cities together in <code>Vec</code>s.</p>
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<p>Here's how you use an <code>Rc</code>. First imagine two structs: one called <code>City</code>, and another called <code>CityData</code>. <code>City</code> has information for one city, and <code>CityData</code> puts all the cities together in <code>Vec</code>s.</p>
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<pre><pre class="playground"><code class="language-rust">#[derive(Debug)]
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<pre><pre class="playground"><code class="language-rust">#[derive(Debug)]
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struct City {
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struct City {
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name: String,
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name: String,
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@ -6649,7 +6649,7 @@ struct City {
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}
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}
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#[derive(Debug)]
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#[derive(Debug)]
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struct Cities {
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struct CityData {
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names: Vec<String>,
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names: Vec<String>,
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histories: Vec<Rc<String>>,
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histories: Vec<Rc<String>>,
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}
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}
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