'Return value of text or False if text is invalid.'

def interpret(self):

    strn = self.lineEdit().text()
    try:
        (val, siprefix, suffix) = fn.siParse(strn, self.opts['regex'])
    except Exception:
        return False
    if ((suffix != self.opts['suffix']) or ((suffix == '') and (siprefix != ''))):
        return False
    val = self.opts['evalFunc'](val)
    if self.opts['int']:
        val = int(fn.siApply(val, siprefix))
    else:
        try:
            val = fn.siApply(val, siprefix)
        except Exception:
            import sys
            sys.excepthook(*sys.exc_info())
            return False
    return val
