File inclusion

?go:include names a file in the local filesystem to include in place. The file can be specified with either an absolute path or a path relative to the page. ?go:include is semantically equivalent to the C preprocessor’s #include directive in that it (a) performs its operation before any code-execution markup (?go:expr, ?go:block, or ?go:top) and (b) is oblivious to the surrounding language semantics. In other words, if one Go Server Page includes the text <block<?go:include other-half.inc ?>, and if other-half.inc begins with the string quote>, the text will expand to <blockquote>. Suggestion: Don’t write code like that. 😉 A more practical example might be as follows:

<p>Blah, blah, blah.</p>
<?go:include footer.inc ?>

where footer.inc contains HTML such as

<footer>
  <address>
    You can find us at<br />
    84 Rainey Street<br />
    Arlen, Texas<br />
    USA
  </address>
</footer>

For security reasons, ?go:include includes only files that lie in the same directory or a subdirectory of the invoking Go Server Page. Hence, a Go Server Page located at /var/www/showcase/index.html could invoke <?go:include helper.inc ?> to paste in /var/www/showcase/helper.inc or <?go:include includes/fragments/header.inc ?> to paste in /var/www/showcase/includes/fragments/header.inc. However, in this case, <?go:include /etc/passwd ?> would result in an error.

File inclusions are currently limited to a depth of 10. That is, file A can include file B, which can include file C, which can include file D, and so forth up to file J but not beyond that. Each file can in fact directly include an unbounded number of other files; only the inclusion depth is limited. The intention is to prevent accidental infinite recursion, such as if file A includes file B, which includes file A.