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| <h1 class="content-header header-section1" id="ref_directive_function" itemprop="headline">function, return</h1> |
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| <div class="page-menu-title">Page Contents</div> |
| <ul><li><a class="page-menu-link" href="#autoid_92" data-menu-target="autoid_92">Synopsis</a></li><li><a class="page-menu-link" href="#autoid_93" data-menu-target="autoid_93">Description</a></li></ul> </div><a name="ref.directive.function"></a><a name="ref.directive.function.return"></a> |
| |
| |
| |
| |
| <h2 class="content-header header-section2" id="autoid_92">Synopsis</h2> |
| |
| |
| |
| <pre class="metaTemplate"> |
| <code class="inline-code"><#function <em class="code-color">name</em> <em class="code-color">param1</em> <em class="code-color">param2</em> <em class="code-color">... paramN</em>> |
| <em class="code-color">...</em> |
| <#return <em class="code-color">returnValue</em>> |
| <em class="code-color">...</em> |
| </#function></code> |
| </pre> |
| |
| |
| <p>Where:</p> |
| |
| <ul> |
| <li> |
| <code class="inline-code"><em class="code-color">name</em></code>: name |
| of method variable (not expression) |
| </li> |
| |
| <li> |
| <code class="inline-code"><em class="code-color">param1</em></code>, |
| <code class="inline-code"><em class="code-color">param2</em></code>, ...etc.: |
| the name of the <a href="dgui_misc_var.html">local |
| variables</a> store the parameter values (not expression), |
| optionally followed by <code class="inline-code">=</code> and the default |
| value (that's an expression). |
| </li> |
| |
| <li> |
| <code class="inline-code"><em class="code-color">paramN</em></code>, the |
| last parameter, may optionally include a trailing ellipsis |
| (<code class="inline-code">...</code>), which indicates the macro takes a |
| variable number of parameters. Local variable |
| <code class="inline-code"><em class="code-color">paramN</em></code> will be a |
| sequence of the extra parameters. |
| </li> |
| |
| <li> |
| <code class="inline-code"><em class="code-color">returnValue</em></code>: |
| the expression that calculates the value of the method |
| call. |
| </li> |
| </ul> |
| |
| <p>The <code class="inline-code">return</code> directive can be used anywhere |
| and for any times between the <code class="inline-code"><#function |
| <em class="code-color">...</em>></code> and |
| <code class="inline-code"></#function></code>.</p> |
| |
| <p>Parameters without default value must precede parameters with |
| default value |
| (<code class="inline-code"><em class="code-color">paramName</em>=<em class="code-color">defaultValue</em></code>).</p> |
| |
| |
| |
| |
| |
| <h2 class="content-header header-section2" id="autoid_93">Description</h2> |
| |
| |
| <p>Creates a method variable (in the current namespace, if you |
| know namespace feature). This directive works in the same way as the |
| <a href="ref_directive_macro.html#ref.directive.macro"><code>macro</code> |
| directive</a>, except that <code class="inline-code">return</code> directive |
| <em>must</em> have a parameter that specifies the return |
| value of the method, and that attempts to write to the output will |
| be ignored. If the <code class="inline-code"></#function></code> is reached |
| (i.e. there was no <code class="inline-code">return |
| <em class="code-color">returnValue</em></code>), then the return |
| value of the method is an undefined variable.</p> |
| |
| <p>Example 1: Creating a method that calculates the average of |
| two numbers:</p> |
| |
| |
| |
| <div class="code-block role-template"> |
| <div class="code-block-label">Template</div><pre class="code-block-body"><#function avg x y> |
| <#return (x + y) / 2> |
| </#function> |
| ${avg(10, 20)}</pre> </div> |
| |
| |
| <p>will print:</p> |
| |
| |
| |
| <div class="code-block role-output"> |
| <div class="code-block-label">Output</div><pre class="code-block-body">15</pre> </div> |
| |
| |
| <p>Example 2: Creating a method that calculates the average of |
| multiple numbers:</p> |
| |
| |
| |
| <div class="code-block role-template"> |
| <div class="code-block-label">Template</div><pre class="code-block-body"><#function avg nums...> |
| <#local sum = 0> |
| <#list nums as num> |
| <#local sum += num> |
| </#list> |
| <#if nums?size != 0> |
| <#return sum / nums?size> |
| </#if> |
| </#function> |
| ${avg(10, 20)} |
| ${avg(10, 20, 30, 40)} |
| ${avg()!"N/A"}</pre> </div> |
| |
| |
| <p>will print:</p> |
| |
| |
| |
| <div class="code-block role-output"> |
| <div class="code-block-label">Output</div><pre class="code-block-body">15 |
| 25 |
| N/A</pre> </div> |
| |
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