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contents/glyph/book/text_editing/attribute_intro.html

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-----
title: "Glyph - Macro attributes"
content-type: page
-----
<nav class="navigation"><a href="/glyph/book/text_editing/macro_intro.html">← Introducing Glyph Macros</a> | <a
    href="/glyph/book/index.html">Contents</a> | <a href="/glyph/book/text_editing/macro_composition.html">Macro
    Composition →</a></nav>
<p>Although a macro can take any number of parameters, they are often no more than two or three, for readibility
  reasons: parameters have no name, but their position within a macro is significant.</p>
<p>If you have something like this:</p>

<div class="CodeRay">
  <div class="code">
    <pre><span class="line-numbers"><a href="#n1" name="n1">1</a></span>custom_image[test.png|50%|50%|Test Image]</pre>
  </div>
</div>

<p>it may still be easy enough to understand what each parameter is used for, but:</p>
<ul>
  <li>you can easily forget that the third parameter is the image width</li>
  <li>if you don&#8217;t want to resize the image, you still have to pass <em>empty parameters</em> to the macro, like
    this: <code>custom_image[test2.png|||Test Image]</code></li>
</ul>
<p>To avoid these situations, some macros which would normally take three or four parameters take optional attributes
  instead, so you can write:</p>
<div class="CodeRay">
  <div class="code">
    <pre><span class="line-numbers"><a href="#n1" name="n1">1</a></span>image[test.png
<span class="line-numbers"><a href="#n2" name="n2">2</a></span>  @width[50%]
<span class="line-numbers"><a href="#n3" name="n3">3</a></span>  @alt[Test Image]
<span class="line-numbers"><a href="#n4" name="n4">4</a></span>  @height[50%]
<span class="line-numbers"><a href="#n5" name="n5">5</a></span>]</pre>
  </div>
</div>

<p>More verbose, of course, but definitely more readable. In this way, if you won't want to scale an image, you can
  safely omit the <code>@width</code> and <code>@height</code> attributes.</p>
<aside class="note">
  <span class="note-title">Note</span>Like parameters, attributes can contain other macros, too.

</aside>
<nav class="navigation"><a href="/glyph/book/text_editing/macro_intro.html">← Introducing Glyph Macros</a> | <a
    href="/glyph/book/index.html">Contents</a> | <a href="/glyph/book/text_editing/macro_composition.html">Macro
    Composition →</a></nav>