Well, I sometimes use redo to parse files with continuation lines, e.g. TCL-Code where \ at the end signs that the expression is continued in the next line...

while (<TCL>) {
  if (s/\\\s*$//) { # if a \ is at the end of the line, remove it
    $_ .= <TCL>;    # and append the next line
    redo;           # and then redo with more of the expression
  } # if

  # do something with the expression
} # while
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This code is not really waterproof for all Tcl-Scripts, since it is just a short example