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| <div class="col-right"><div class="page-content"><div class="page-title"><div class="pagers top"><a class="paging-arrow previous" href="dgui_misc_whitespace.html"><span>Previous</span></a><a class="paging-arrow next" href="pgui.html"><span>Next</span></a></div><div class="title-wrapper"> |
| <h1 class="content-header header-section1" id="dgui_misc_alternativesyntax" itemprop="headline">Alternative (square bracket) syntax</h1> |
| </div></div><div class="page-menu"> |
| <div class="page-menu-title">Page Contents</div> |
| <ul><li><a class="page-menu-link" href="#dgui_misc_alternativesyntax_tag" data-menu-target="dgui_misc_alternativesyntax_tag">Square bracket tag syntax</a></li><li><a class="page-menu-link" href="#dgui_misc_alternativesyntax_interpolation" data-menu-target="dgui_misc_alternativesyntax_interpolation">Square bracket interpolation syntax</a></li></ul> </div><p>Sometimes the generated content uses symbols that clashes with |
| the default FreeMarker syntax (typically, |
| <code class="inline-code">${<em class="code-color">...</em>}</code>-s that FreeMarker |
| should print as is, without interpretation), or you use some tool that |
| is confused by the default FreeMarker syntax (typically by |
| <code class="inline-code"><</code> and <code class="inline-code">></code>). While usually |
| there are tricks to work those cases around (like you can use |
| <code class="inline-code">${'$'}{x}</code> to print <code class="inline-code">${x}</code> as is) , |
| they are often too inconvenient. Thus, the interpolation syntax can be |
| configured to be like <code class="inline-code">[=x]</code> instead of |
| <code class="inline-code">${x}</code>. Also, independently of that, the FreeMarker |
| tag syntax can be configured to use <code class="inline-code">[]</code>, like in |
| <code class="inline-code">[#if x]<em class="code-color">...</em>[/#if]</code>.</p> <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>While both the "tag syntax" and |
| "interpolation syntax" can be configured to use square |
| brackets, they are totally independent configuration settings. Thus, |
| the overall syntax can be like <code class="inline-code">[#if x]${y}[/#if]</code>, |
| or like <code class="inline-code"><#if x>[=y]</#if></code> as |
| well.</p> |
| </div> |
| |
| |
| |
| |
| |
| <h2 class="content-header header-section2" id="dgui_misc_alternativesyntax_tag">Square bracket tag syntax</h2> |
| |
| |
| <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>This section is about the <em>tag</em> syntax, |
| not the <a href="#dgui_misc_alternativesyntax_interpolation"><em>interpolation</em> |
| syntax</a>. Don't confuse the two, they are independent.</p> |
| </div> |
| |
| |
| <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>This feature exists since FreeMarker 2.3.4.</p> |
| </div> |
| |
| |
| <p>FreeMarker supports an alternative tag syntax, where |
| <code class="inline-code">[</code> and <code class="inline-code">]</code> is used instead of |
| <code class="inline-code"><</code> and <code class="inline-code">></code> in FreeMarker |
| directives and comments, for example:</p> |
| |
| <ul> |
| <li> |
| Calling predefined directive: <code class="inline-code">[#list animals as |
| animal]<em class="code-color">...</em>[/#list]</code> |
| </li> |
| |
| <li> |
| Calling user-defined directive: <code class="inline-code">[@myMacro |
| /]</code> |
| </li> |
| |
| <li> |
| Comment: <code class="inline-code">[#-- the comment --]</code> |
| </li> |
| </ul> |
| |
| <p>To use square tag syntax instead of the default one, the |
| programmers should configure FreeMarker so <span class="marked-for-programmers">(see |
| <code class="inline-code">Configuraton.setTagSyntax</code>, or the |
| <code class="inline-code">tag_syntax</code> setting)</span>. However, the tag |
| syntax can also be enforced in the template, with the <a href="ref_directive_ftl.html"><code>ftl</code> directive</a> |
| (see later).</p> |
| |
| <p>For example, this is how the last example of the <a href="dgui_quickstart_template.html">Getting Started</a> looks with |
| the alternative syntax:</p> |
| |
| |
| |
| <div class="code-block role-template"> |
| <div class="code-block-label">Template</div><pre class="code-block-body"><p>We have these animals: |
| <table border=1> |
| <tr><th>Name<th>Price |
| <strong>[#list animals as animal]</strong> |
| <tr> |
| <td> |
| <strong>[#if animal.size == "large"]</strong><b><strong>[/#if]</strong> |
| ${animal.name} |
| <strong>[#if animal.size == "large"]</strong></b><strong>[/#if]</strong> |
| <td>${animal.price} Euros |
| <strong>[/#list]</strong> |
| </table></pre> </div> |
| |
| |
| <p>The square bracket and the default (angle bracket) syntax are |
| mutually exclusive within a template; they can't be mixed. If the |
| template uses square bracket tag syntax, then things like |
| <code class="inline-code"><#if <em class="code-color">...</em>></code> will |
| be just static text, not FTL tags. Similarly, if the template uses |
| the angle brackets tag syntax, things like <code class="inline-code">[#if |
| <em class="code-color">...</em>]</code> are static text, not FTL |
| tags.</p> |
| |
| <p>If you start the file with <code class="inline-code">[#ftl |
| <em class="code-color">...</em>]</code> (where the |
| <code class="inline-code"><em class="code-color">...</em></code> stands for the |
| optional parameters; of course <code class="inline-code">[#ftl]</code> works too) |
| the file will use square bracket <em>tag</em> syntax |
| regardless of the configuration settings (but that does |
| <em>not</em> change the interpolation syntax to |
| <code class="inline-code">[=...]</code>). Similarly, if you start the file with |
| <code class="inline-code"><#ftl <em class="code-color">...</em>></code> the |
| file will use the normal (angle bracket) tag syntax. If there is no |
| <code class="inline-code">ftl</code> directive in the file, then the programmer |
| decides what the tag <em>syntax</em> will be by |
| configuring FreeMarker <span class="marked-for-programmers">(programmers |
| see <code class="inline-code">Configuration.setTagSyntax(int)</code> in the API |
| javadocs)</span>. Most probably the programmers use the factory |
| default.</p> |
| |
| |
| |
| |
| |
| <h2 class="content-header header-section2" id="dgui_misc_alternativesyntax_interpolation">Square bracket interpolation syntax</h2> |
| |
| |
| <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>This section is about the <em>interpolation</em> |
| syntax, not the <a href="#dgui_misc_alternativesyntax_tag"><em>tag</em> |
| syntax</a>. Don't confuse the two, they are independent.</p> |
| </div> |
| |
| |
| <div class="callout note"> |
| <strong class="callout-label">Note:</strong> |
| |
| <p>This feature exists since FreeMarker 2.3.28</p> |
| </div> |
| |
| |
| <p>In this case instead of |
| <code class="inline-code">${<em class="code-color">expression</em>}</code> (and the |
| deprecated |
| <code class="inline-code">#{<em class="code-color">expression</em>}</code>) you |
| write <code class="inline-code">[=<em class="code-color">expression</em>]</code>. |
| This syntax is activated by the programmers from the configuration |
| <span class="marked-for-programmers">(see |
| <code class="inline-code">Configuration.setInterpolationSyntax</code> in the Java |
| API)</span>; unlike the tag syntax, it can't be specified inside |
| the template. It can be used both together with, and without the |
| <a href="#dgui_misc_alternativesyntax_tag">square bracket |
| <em>tag</em> syntax</a>, as they are technically |
| unrelated, but it's probably more aesthetic to use square bracket |
| tag syntax when you use square bracket interpolation syntax:</p> |
| |
| |
| |
| <div class="code-block role-template"> |
| <div class="code-block-label">Template</div><pre class="code-block-body">[#-- |
| Note: |
| This example uses both interpolation_syntax=squareBracket and tag_syntax=squareBracket, |
| but you can also use interpolation_syntax=squareBracket and tag_syntax=angleBracket. |
| --] |
| <p>We have these animals: |
| <table border=1> |
| <tr><th>Name<th>Price |
| [#list animals as animal] |
| <tr> |
| <td> |
| [#if animal.size == "large"]<b>[/#if] |
| <strong>[=animal.name]</strong> |
| [#if animal.size == "large"]</b>[/#if] |
| <td><strong>[=animal.price]</strong> Euros |
| [/#list] |
| </table></pre> </div> |
| |
| |
| <p>When square bracket interpolation syntax is used, |
| <code class="inline-code">${<em class="code-color">expression</em>}</code> and |
| <code class="inline-code">#{<em class="code-color">expression</em>}</code> in the |
| template will be just static text, which is printed as is. This is |
| mostly useful if you generate output that should contain those |
| (especially |
| <code class="inline-code">${<em class="code-color">expression</em>}</code> is |
| frequent), such as when generating JSP files.</p> |
| |
| <p>There's also a third tag syntax, "dollar", where |
| only the interpolation syntax is |
| <code class="inline-code">${<em class="code-color">expression</em>}</code>, and the |
| deprecated |
| <code class="inline-code">#{<em class="code-color">expression</em>}</code> is just |
| static text. (The one where |
| <code class="inline-code">#{<em class="code-color">expression</em>}</code> is still |
| an interpolation is called the "legacy" interpolation |
| syntax, and is the default for backward compatibility.)</p> |
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