Operator Type:
Operator Scope of Action:
Operator Purpose:
Data Type Returned:
Operator First Added:
Operator in Current Baseline:
Operator Last Altered:
Operator Has Optional Arguments:
Function [other Function type actions]
Item [operators of similar scope]
Stream parsing [other Stream parsing operators]
boolean test
v9.1.0
Baseline
As at baseline
String.try{ actionStr }[.thenTry{ actionStr }]
This saves the value of a (String-type) attribute (the stream source) and evaluates .try{actionStr}. It the evaluation fails, the app restores the string and allows it to processed it a different way in the chained .thenTry{actionStr} operation. If all evaluations fail, the original value of String stream source is restored.
A .try{} may be followed by one or more .thenTry{} clauses. If the original .try{} succeeds the evaluated result is returned and all subsequent .thenTry{} clauses are ignored. If the original .try{} fails, then each .thenTry{} is attempted in turn, until a result is returned. If all expression evaluations fail, the original value of String is returned.
The current success/failure state can be tested using the .failed() operator.
For example:
$MyString.try{
$MyString=$MyString.skipToWord("To:").captureWord;
}.thenTry{
fail(); //signal an explicit failure and return a 'false' value to a calling action
};
looks for strings such as "To:John Doe"
If the string "To:" is not found, $MyString will be unchanged. If found, $MyString's value is set to the word that follows, up to the next whitespace character or the end of the string, i.e. "John".
See also—notes linking to here: