fail()

fail()

fail

The fail operator makes an explicit declaration of a failure, and if invoked only ever returns false.

Often, in stream processing a failure occurs implicitly, for example because the end of the processed string is reached without finding the desired data. However, sometimes, there is a definite need to signal failure; for example, because the parsed data are invalid.

For example:

	$MyString.try{
	   $MyString.skipTo(":").captureWord("TheWord");
	   if($TheWord.contains("None")) {
	      fail();
	   }
	}

The above skips through $MyString to the first colon and then captures the next discrete word after the colon into $TheWord. The action fails if:

• if there is no colon
• if there is no word after the colon
• if $TheWord contains "None" as a case-sensitive exact full match or substring match.

See also—notes linking to here:

• String.failed()
• Functional control structure operators