#### 37.4.4 Using macros to process lists

Suppose you want to generate a different set of sidebar navigation links for each major section of a Web site, where each section is in a single DITA file that DITA2Go splits into named pages (see §27. Splitting and extracting files). For each page, the sidebar item that names that page should not be a link, because a live link to the current page confuses people.

You need a slightly different list of sidebar items on every HTML page, to avoid a same-page link. But the logic is always the same, as are the names of files and the titles to be displayed. What is needed is a macro that takes into account which item should not be linked.

Your configuration file could include a pair of lists, one with file names and the other with matching sidebar titles, like this:

[DITA_File]
1 = homepage
2 = descript
3 = operate
4 = testimonial
5 = demo
6 = order

[SideTitle]
1 = Widgets
2 = What a Widget Does
3 = How to Use a Widget
4 = What Users Say About Widgets
5 = Get a Demo Widget
6 = Order Widgets On Line

You could process the two lists with this macro:

[Sidebar]
<$$val=2><$$maxval=6>\
<$_while ($$val <= $$maxval)>\
<$_if ($$_currbase is $$DITA_File[$$val])>\
<p class="SidebarTxt"><$$SideTitle[$$val]></p>\
<$_else>\
<p class="SidebarTxt"><a class="SidebarLnk"\
href="<$$DITA_File[$$val]>.htm"><$$SideTitle[$$val]></a></p>\
<$_endif>
<$$val++>
<$_endwhile>

Previous Topic: 37.4.3 Initializing list variables

Next Topic: 37.4.5 Using pointers to process lists

Parent Topic: 37.4 Using multiple-value list variables

Sibling Topics:

37.4.1 Understanding list-variable syntax

37.4.2 Assigning a value to a list-variable item

37.4.3 Initializing list variables

37.4.5 Using pointers to process lists

37.4.6 Using a list instead of a conditional expression

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