title: How to get string in Tcl expansion substitution
body: <p>To follow up with an <a href="https://stackoverflow.com/questions/26169533/how-to-call-tcl-command-with-conditional-option">earlier</a> question using Tcl version 8.5 I have:</p>
  
  <pre><code>set defs {}
  array set options $::argv
  set git_ver $options(-git_ver)
  lappend defs {-verilog_define GIT_VERSION=${git_ver}}
  foreach i $defs { puts $i }
  </code></pre>
  
  <p>What I get from puts is:</p>
  
  <pre><code>-verilog_define GIT_VERSION=${git_ver}
  </code></pre>
  
  <p>But how do I get the string representation of my variable git_ver?</p>