perlquestion tlm <p><b>Update:</b> As [Not_a_Number] points out below, the behavior described in this post applies not only to 1 (as I originally stated), but to 0 as well. And, after reading [merlyn]'s post, well, it looks like there's a <i>huge</i> number of constants&mdash;all those strings beginning with "di", "ds", or "ig"&mdash;that perl won't warn about when they are evaluated in a void context. See the [id://475508|code] responsible for this behavior, kindly posted by [Anonymous Monk|AM].</p> <hr> <p>OK, here's another idle Perl arcana question. A scalar constant in a void context will result in a warning, <em>unless</em> this constant evaluates to a <em>numeric</em> value of 1; e.g.: <c> % perl -wce 5 Useless use of a constant in void context at -e line 1. -e syntax OK % perl -wce 1 -e syntax OK % perl -wce '5**0' -e syntax OK % perl -wce 1.00 -e syntax OK % perl -wce 'q(1)' Useless use of a constant in void context at -e line 1. -e syntax OK </c> Does anyone know the rationale for this special dispensation for (numeric) 1? The only one I can think of (and it's a pretty tortured one) is that it silences the warning that would have otherwise been triggered by the usual <tt>require</tt>-appeasing <tt>"1;"</tt> when one checks a module's syntax using <tt>perl -wc</tt>.</p> <div class="pmsig"><div class="pmsig-439528"> <p><small>the lowliest monk</small></p> </div></div>