A square can't have different width and height
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@ -13,8 +13,8 @@ type geometry interface {
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}
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// For our example we'll implement this interface on
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// `square` and `circle` types.
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type square struct {
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// `rect` and `circle` types.
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type rect struct {
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width, height float64
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}
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type circle struct {
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@ -23,12 +23,12 @@ type circle struct {
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// To implement an interface in Go, we just need to
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// implement all the methods in the interface. Here we
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// implement `geometry` on `square`s.
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func (s square) area() float64 {
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return s.width * s.height
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// implement `geometry` on `rect`s.
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func (r rect) area() float64 {
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return r.width * r.height
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}
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func (s square) perim() float64 {
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return 2*s.width + 2*s.height
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func (r rect) perim() float64 {
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return 2*r.width + 2*r.height
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}
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// The implementation for `circle`s.
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@ -50,13 +50,13 @@ func measure(g geometry) {
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}
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func main() {
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s := square{width: 3, height: 4}
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r := rect{width: 3, height: 4}
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c := circle{radius: 5}
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// The `circle` and `square` struct types both
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// The `circle` and `rect` struct types both
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// implement the `geometry` interface so we can use
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// instances of
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// these structs as arguments to `measure`.
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measure(s)
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measure(r)
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measure(c)
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}
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@ -1,2 +1,2 @@
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9bafbade1f5effc38be233c3fd12cbdd7c6e226d
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guxTzcucR-
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3547b935d1e0322c0fb696726c27cae53a275e0a
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313UebA3rD
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@ -40,7 +40,7 @@ signatures.</p>
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/guxTzcucR-"><img title="Run code" src="play.png" class="run" /></a>
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<a href="http://play.golang.org/p/313UebA3rD"><img title="Run code" src="play.png" class="run" /></a>
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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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</pre></div>
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@ -79,12 +79,12 @@ signatures.</p>
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<tr>
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<td class="docs">
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<p>For our example we’ll implement this interface on
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<code>square</code> and <code>circle</code> types.</p>
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<code>rect</code> and <code>circle</code> types.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">type</span> <span class="nx">square</span> <span class="kd">struct</span> <span class="p">{</span>
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<div class="highlight"><pre><span class="kd">type</span> <span class="nx">rect</span> <span class="kd">struct</span> <span class="p">{</span>
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<span class="nx">width</span><span class="p">,</span> <span class="nx">height</span> <span class="kt">float64</span>
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<span class="p">}</span>
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<span class="kd">type</span> <span class="nx">circle</span> <span class="kd">struct</span> <span class="p">{</span>
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@ -99,16 +99,16 @@ signatures.</p>
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<td class="docs">
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<p>To implement an interface in Go, we just need to
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implement all the methods in the interface. Here we
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implement <code>geometry</code> on <code>square</code>s.</p>
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implement <code>geometry</code> on <code>rect</code>s.</p>
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">s</span> <span class="nx">square</span><span class="p">)</span> <span class="nx">area</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
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<span class="k">return</span> <span class="nx">s</span><span class="p">.</span><span class="nx">width</span> <span class="o">*</span> <span class="nx">s</span><span class="p">.</span><span class="nx">height</span>
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<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">r</span> <span class="nx">rect</span><span class="p">)</span> <span class="nx">area</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
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<span class="k">return</span> <span class="nx">r</span><span class="p">.</span><span class="nx">width</span> <span class="o">*</span> <span class="nx">r</span><span class="p">.</span><span class="nx">height</span>
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<span class="p">}</span>
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<span class="kd">func</span> <span class="p">(</span><span class="nx">s</span> <span class="nx">square</span><span class="p">)</span> <span class="nx">perim</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
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<span class="k">return</span> <span class="mi">2</span><span class="o">*</span><span class="nx">s</span><span class="p">.</span><span class="nx">width</span> <span class="o">+</span> <span class="mi">2</span><span class="o">*</span><span class="nx">s</span><span class="p">.</span><span class="nx">height</span>
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<span class="kd">func</span> <span class="p">(</span><span class="nx">r</span> <span class="nx">rect</span><span class="p">)</span> <span class="nx">perim</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
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<span class="k">return</span> <span class="mi">2</span><span class="o">*</span><span class="nx">r</span><span class="p">.</span><span class="nx">width</span> <span class="o">+</span> <span class="mi">2</span><span class="o">*</span><span class="nx">r</span><span class="p">.</span><span class="nx">height</span>
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<span class="p">}</span>
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</pre></div>
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@ -160,7 +160,7 @@ to work on any <code>geometry</code>.</p>
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<td class="code leading">
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
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<span class="nx">s</span> <span class="o">:=</span> <span class="nx">square</span><span class="p">{</span><span class="nx">width</span><span class="p">:</span> <span class="mi">3</span><span class="p">,</span> <span class="nx">height</span><span class="p">:</span> <span class="mi">4</span><span class="p">}</span>
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<span class="nx">r</span> <span class="o">:=</span> <span class="nx">rect</span><span class="p">{</span><span class="nx">width</span><span class="p">:</span> <span class="mi">3</span><span class="p">,</span> <span class="nx">height</span><span class="p">:</span> <span class="mi">4</span><span class="p">}</span>
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<span class="nx">c</span> <span class="o">:=</span> <span class="nx">circle</span><span class="p">{</span><span class="nx">radius</span><span class="p">:</span> <span class="mi">5</span><span class="p">}</span>
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</pre></div>
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@ -169,7 +169,7 @@ to work on any <code>geometry</code>.</p>
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<tr>
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<td class="docs">
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<p>The <code>circle</code> and <code>square</code> struct types both
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<p>The <code>circle</code> and <code>rect</code> struct types both
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implement the <code>geometry</code> interface so we can use
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instances of
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these structs as arguments to <code>measure</code>.</p>
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@ -177,7 +177,7 @@ these structs as arguments to <code>measure</code>.</p>
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</td>
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<td class="code">
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<div class="highlight"><pre> <span class="nx">measure</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
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<div class="highlight"><pre> <span class="nx">measure</span><span class="p">(</span><span class="nx">r</span><span class="p">)</span>
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<span class="nx">measure</span><span class="p">(</span><span class="nx">c</span><span class="p">)</span>
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<span class="p">}</span>
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</pre></div>
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