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copied!<h2>Best Solution: Expansion Substitution</h2> <p>The right approach is to ensure that the outer procedure (in stack terms) calls the inner one correctly; if multiple arguments are expected, that's what should be supplied. With the advent of Tcl 8.5, that's trivially done with a little language syntax called an <strong><em>expansion substitution</em></strong>:</p> <pre><code>proc abc1 {args} { puts "$args" array set arg $args set l2 [array get arg] abc {*}$l2 # Or combine the two lines above into: abc {*}[array get arg] } </code></pre> <p>All the <a href="http://www.tcl.tk/man/tcl8.5/TclCmd/Tcl.htm#M9" rel="noreferrer"><code>{*}</code></a> does is say that the rest of the word should be broken up (using list syntax rules) and used as multiple arguments instead of Tcl's default “one visual word forms a single word” rules. It's <em>ideal</em> for this.</p> <h2>Old Solution: Eval Command</h2> <p>If you're still using old versions of Tcl for some reason (i.e., Tcl 8.4 or before) then you use the <code>eval</code> command instead of the above syntax:</p> <pre><code>eval abc $l2 </code></pre> <p>There are some somewhat-more-efficient approaches to the above <code>eval</code>, which you might see in older code; for example:</p> <pre><code>eval [linsert $l2 0 abc] eval [list abc] [lrange $l2 0 end] # ... etc ... </code></pre> <p>But really they're all rendered obsolete by <code>abc {*}$l2</code> which is shorter, simpler to write, and faster. (It's just not available in 8.4 or before, and too many deployments have yet to upgrade.) <em>Use the expansion syntax if you can.</em> Indeed, idiomatic Tcl code for 8.5 and later hardly ever needs <code>eval</code>; the extent to which this has proved true has even been rather surprising to the language's maintainers.</p>

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