From 17359b7fb42a96a5e405d7a14335752a866b5ea7 Mon Sep 17 00:00:00 2001
From: Kevin Ho <kevin.ho01@sap.com>
Date: Fri, 3 Jan 2025 15:14:28 -0800
Subject: [PATCH] added type assertion example

---
 examples/interfaces/interfaces.go   | 14 ++++++++++
 examples/interfaces/interfaces.hash |  4 +--
 examples/interfaces/interfaces.sh   |  1 +
 public/interfaces                   | 41 +++++++++++++++++++++++++----
 4 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/examples/interfaces/interfaces.go b/examples/interfaces/interfaces.go
index 806ffa7d4..e5e00b805 100644
--- a/examples/interfaces/interfaces.go
+++ b/examples/interfaces/interfaces.go
@@ -41,6 +41,12 @@ func (c circle) perim() float64 {
 	return 2 * math.Pi * c.radius
 }
 
+// `circle` has a method called `circum` not part of `geometry` interface.
+// `circum` is an alias for `perim`
+func (c circle) circum() float64 {
+	return c.perim()
+}
+
 // If a variable has an interface type, then we can call
 // methods that are in the named interface. Here's a
 // generic `measure` function taking advantage of this
@@ -61,4 +67,12 @@ func main() {
 	// these structs as arguments to `measure`.
 	measure(r)
 	measure(c)
+
+	// Type assertion can be performed
+	// to access methods not part of the `geometry` interface
+	var shape geometry
+	shape = circle{radius: 6}
+	if c, ok := shape.(circle); ok {
+		fmt.Println(c.circum())
+	}
 }
diff --git a/examples/interfaces/interfaces.hash b/examples/interfaces/interfaces.hash
index b228f689a..0822ae0bd 100644
--- a/examples/interfaces/interfaces.hash
+++ b/examples/interfaces/interfaces.hash
@@ -1,2 +1,2 @@
-d4ea9541521cfee94107ba9331d0dabb1f9f16c1
-XJASG4MxBQr
+f536687ba84047d88affba161c521d72b3759627
+iRa1sADCdAw
diff --git a/examples/interfaces/interfaces.sh b/examples/interfaces/interfaces.sh
index b71147638..452a91e76 100644
--- a/examples/interfaces/interfaces.sh
+++ b/examples/interfaces/interfaces.sh
@@ -5,6 +5,7 @@ $ go run interfaces.go
 {5}
 78.53981633974483
 31.41592653589793
+37.69911184307752
 
 # To learn more about Go's interfaces, check out this
 # [great blog post](https://jordanorelli.tumblr.com/post/32665860244/how-to-use-interfaces-in-go).
diff --git a/public/interfaces b/public/interfaces
index 15a381113..1b48e98f5 100644
--- a/public/interfaces
+++ b/public/interfaces
@@ -45,7 +45,7 @@ signatures.</p>
             
           </td>
           <td class="code leading">
-            <a href="https://go.dev/play/p/XJASG4MxBQr"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
+            <a href="https://go.dev/play/p/iRa1sADCdAw"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
           <pre class="chroma"><code><span class="line"><span class="cl"><span class="kn">package</span> <span class="nx">main</span></span></span></code></pre>
           </td>
         </tr>
@@ -128,6 +128,20 @@ implement <code>geometry</code> on <code>rect</code>s.</p>
           </td>
         </tr>
         
+        <tr>
+          <td class="docs">
+            <p><code>circle</code> has a method called <code>circum</code> not part of <code>geometry</code> interface.
+<code>circum</code> is an alias for <code>perim</code></p>
+
+          </td>
+          <td class="code leading">
+            
+          <pre class="chroma"><code><span class="line"><span class="cl"><span class="kd">func</span> <span class="p">(</span><span class="nx">c</span> <span class="nx">circle</span><span class="p">)</span> <span class="nf">circum</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
+</span></span><span class="line"><span class="cl">    <span class="k">return</span> <span class="nx">c</span><span class="p">.</span><span class="nf">perim</span><span class="p">()</span>
+</span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre>
+          </td>
+        </tr>
+        
         <tr>
           <td class="docs">
             <p>If a variable has an interface type, then we can call
@@ -166,10 +180,26 @@ instances of
 these structs as arguments to <code>measure</code>.</p>
 
           </td>
-          <td class="code">
+          <td class="code leading">
             
           <pre class="chroma"><code><span class="line"><span class="cl">    <span class="nf">measure</span><span class="p">(</span><span class="nx">r</span><span class="p">)</span>
-</span></span><span class="line"><span class="cl">    <span class="nf">measure</span><span class="p">(</span><span class="nx">c</span><span class="p">)</span>
+</span></span><span class="line"><span class="cl">    <span class="nf">measure</span><span class="p">(</span><span class="nx">c</span><span class="p">)</span></span></span></code></pre>
+          </td>
+        </tr>
+        
+        <tr>
+          <td class="docs">
+            <p>Type assertion can be performed
+to access methods not part of the <code>geometry</code> interface</p>
+
+          </td>
+          <td class="code">
+            
+          <pre class="chroma"><code><span class="line"><span class="cl">    <span class="kd">var</span> <span class="nx">shape</span> <span class="nx">geometry</span>
+</span></span><span class="line"><span class="cl">    <span class="nx">shape</span> <span class="p">=</span> <span class="nx">circle</span><span class="p">{</span><span class="nx">radius</span><span class="p">:</span> <span class="mi">6</span><span class="p">}</span>
+</span></span><span class="line"><span class="cl">    <span class="k">if</span> <span class="nx">c</span><span class="p">,</span> <span class="nx">ok</span> <span class="o">:=</span> <span class="nx">shape</span><span class="p">.(</span><span class="nx">circle</span><span class="p">);</span> <span class="nx">ok</span> <span class="p">{</span>
+</span></span><span class="line"><span class="cl">        <span class="nx">fmt</span><span class="p">.</span><span class="nf">Println</span><span class="p">(</span><span class="nx">c</span><span class="p">.</span><span class="nf">circum</span><span class="p">())</span>
+</span></span><span class="line"><span class="cl">    <span class="p">}</span>
 </span></span><span class="line"><span class="cl"><span class="p">}</span></span></span></code></pre>
           </td>
         </tr>
@@ -190,7 +220,8 @@ these structs as arguments to <code>measure</code>.</p>
 </span></span></span><span class="line"><span class="cl"><span class="go">14
 </span></span></span><span class="line"><span class="cl"><span class="go">{5}
 </span></span></span><span class="line"><span class="cl"><span class="go">78.53981633974483
-</span></span></span><span class="line"><span class="cl"><span class="go">31.41592653589793</span></span></span></code></pre>
+</span></span></span><span class="line"><span class="cl"><span class="go">31.41592653589793
+</span></span></span><span class="line"><span class="cl"><span class="go">37.69911184307752</span></span></span></code></pre>
           </td>
         </tr>
         
@@ -221,7 +252,7 @@ these structs as arguments to <code>measure</code>.</p>
     </div>
     <script>
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