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| <div class="section-level-extent" id="Invoking-Macros"> |
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| Next: <a href="Macro-Details.html" accesskey="n" rel="next">Macro Details and Caveats</a>, Previous: <a href="Defining-Macros.html" accesskey="p" rel="prev">Defining Macros</a>, Up: <a href="Defining-New-Texinfo-Commands.html" accesskey="u" rel="up">Defining New Texinfo Commands</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Variable-Index.html" title="Index" rel="index">Index</a>]</p> |
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| <h3 class="section" id="Invoking-Macros-1">16.2 Invoking Macros</h3> |
| |
| <a class="index-entry-id" id="index-Invoking-macros"></a> |
| <a class="index-entry-id" id="index-Expanding-macros"></a> |
| <a class="index-entry-id" id="index-Running-macros"></a> |
| <a class="index-entry-id" id="index-Macro-invocation"></a> |
| |
| <p>After a macro is defined (see the previous section), you can |
| <em class="dfn">invoke</em> (use) it in your document like this: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">@<var class="var">macroname</var> {<var class="var">arg1</var>, <var class="var">arg2</var>, …} |
| </pre></div> |
| |
| <p>and the result will be more or less as if you typed the body of |
| <var class="var">macroname</var> at that spot. For example: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">@macro foo {p, q} |
| Together: \p\ & \q\. |
| @end macro |
| @foo{a, b} |
| </pre></div> |
| |
| <p>produces: |
| </p> |
| <div class="display"> |
| <pre class="display-preformatted">Together: a & b. |
| </pre></div> |
| |
| <a class="index-entry-id" id="index-Backslash_002c-and-macros"></a> |
| <p>Thus, the arguments and parameters are separated by commas and |
| delimited by braces; any whitespace after (but not before) a comma is |
| ignored. The braces are required in the invocation even when the |
| macro takes no arguments, consistent with other Texinfo commands. For |
| example: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">@macro argless {} |
| No arguments here. |
| @end macro |
| @argless{} |
| </pre></div> |
| |
| <p>produces: |
| </p> |
| <div class="display"> |
| <pre class="display-preformatted">No arguments here. |
| </pre></div> |
| |
| <a class="index-entry-id" id="index-Comma_002c-in-macro-arguments"></a> |
| <p>Passing macro arguments containing commas requires care, since |
| commas also separate the arguments. To include a comma character in |
| an argument, the most reliable method is to use the <code class="code">@comma{}</code> |
| command. For <code class="code">makeinfo</code>, you can also prepend a backslash |
| character, as in ‘<samp class="samp">\,</samp>’, but this does not work with TeX. |
| </p> |
| <a class="index-entry-id" id="index-Automatic-quoting-of-commas-for-some-macros"></a> |
| <a class="index-entry-id" id="index-Quoting_002c-automatic-for-some-macros"></a> |
| <p>It’s not always necessary to worry about commas. To facilitate use of |
| macros, <code class="command">makeinfo</code> implements two rules for <em class="dfn">automatic |
| quoting</em> in some circumstances: |
| </p> |
| <ol class="enumerate"> |
| <li> If a macro takes only one argument, all commas in its invocation |
| are quoted by default. For example: |
| |
| <div class="example"> |
| <div class="group"><pre class="example-preformatted">@macro TRYME{text} |
| @strong{TRYME: \text\} |
| @end macro |
| |
| @TRYME{A nice feature, though it can be dangerous.} |
| </pre></div></div> |
| |
| <p>will produce the following output |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted"><strong class="strong">TRYME: A nice feature, though it can be dangerous.</strong> |
| </pre></div> |
| |
| <p>And indeed, it can. Namely, <code class="command">makeinfo</code> does not control the |
| number of arguments passed to one-argument macros, so be careful when |
| you invoke them. |
| </p> |
| </li><li> If a macro invocation includes another command (including a |
| recursive invocation of itself), any commas in the nested command |
| invocation(s) are quoted by default. For example, in |
| |
| <div class="example"> |
| <pre class="example-preformatted">@say{@strong{Yes, I do}, person one} |
| </pre></div> |
| |
| <p>the comma after ‘<samp class="samp">Yes</samp>’ is implicitly quoted. Here’s another |
| example, with a recursive macro: |
| </p> |
| <div class="example"> |
| <div class="group"><pre class="example-preformatted">@rmacro cat{a,b} |
| \a\\b\ |
| @end rmacro |
| |
| @cat{@cat{foo, bar}, baz} |
| </pre></div></div> |
| |
| <p>will produce the string ‘<samp class="samp">foobarbaz</samp>’. |
| </p> |
| </li><li> Otherwise, a comma should be explicitly quoted, as above, for it |
| to be treated as a part of an argument. |
| </li></ol> |
| |
| <a class="index-entry-id" id="index-Backslash_002c-in-macro-arguments"></a> |
| <a class="index-entry-id" id="index-Braces_002c-in-macro-arguments"></a> |
| <p>The backslash itself can be quoted in macro arguments with another |
| backslash. For example: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">@<var class="var">macname</var> {\\bleh} |
| </pre></div> |
| |
| <p>will pass the argument ‘<samp class="samp">\bleh</samp>’ to <var class="var">macname</var>. |
| </p> |
| <p><code class="command">makeinfo</code> also recognizes ‘<samp class="samp">\{</samp>’ and ‘<samp class="samp">\}</samp>’ sequences |
| for curly braces, but these are not recognized by the implementation in |
| TeX. There should, however, rarely be a need for these, as they are |
| only needed when a macro argument contains unbalanced braces. |
| </p> |
| <p>If a macro is defined to take exactly one argument, it can be |
| invoked without any braces, taking all of the line after the macro name |
| as the argument. For example: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">@macro bar {p} |
| Twice: \p\ & \p\. |
| @end macro |
| @bar aah |
| </pre></div> |
| |
| <p>produces: |
| </p> |
| <div class="display"> |
| <pre class="display-preformatted">Twice: aah & aah. |
| </pre></div> |
| |
| <p>In these arguments, there is no escaping of special characters, so each |
| ‘<samp class="samp">\</samp>’ stands for itself. |
| </p> |
| <p>If a macro is defined to take more than one argument, but is called |
| with only one (in braces), the remaining arguments are set to the |
| empty string, and no error is given. For example: |
| </p> |
| <div class="example"> |
| <pre class="example-preformatted">@macro addtwo {p, q} |
| Both: \p\\q\. |
| @end macro |
| @addtwo{a} |
| </pre></div> |
| |
| <p>produces simply: |
| </p> |
| <div class="display"> |
| <pre class="display-preformatted">Both: a. |
| </pre></div> |
| |
| |
| </div> |
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| Next: <a href="Macro-Details.html">Macro Details and Caveats</a>, Previous: <a href="Defining-Macros.html">Defining Macros</a>, Up: <a href="Defining-New-Texinfo-Commands.html">Defining New Texinfo Commands</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Variable-Index.html" title="Index" rel="index">Index</a>]</p> |
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