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<title>UK TeX FAQ -- question label edef</title>
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<h3><code>\</code><code>edef</code> does not work with <code>\</code><code>protect</code></h3>
<p>Robust LaTeX commands are either “naturally robust” — meaning that
they never need <code>\</code><code>protect</code>, or “self-protected” — meaning that
they have <code>\</code><code>protect</code> built in to their definition in some
way. Self-protected commands are robust only in a context where the
<code>\</code><code>protect</code> mechanism is properly handled. The body of an
<code>\</code><code>edef</code> definition doesn’t handle <code>\</code><code>protect</code> properly, since
<code>\</code><code>edef</code> is a TeX primitive rather than a LaTeX command.
<p>This problem is resolved by a LaTeX internal command
<code>\</code><code>protected@edef</code>, which does the job of <code>\</code><code>edef</code> while keeping the
<code>\</code><code>protect</code> mechanism working. There’s a corresponding
<code>\</code><code>protected@xdef</code> which does the job of <code>\</code><code>xdef</code>.
<p>Of course, these commands need to be tended carefully, since they’re
internal: see <a href="FAQ-atsigns.html">’@’ in control sequence names</a>.
<p><p>This question on the Web: <a href="http://www.tex.ac.uk/cgi-bin/texfaq2html?label=edef">http://www.tex.ac.uk/cgi-bin/texfaq2html?label=edef</a>
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