Return errors and use the check

Do not return invalid values when an error occurs; instead return the error. As much as possible, avoid the use of T|error in variable declarations. Instead, use check and add error to the return type

Bad Code

function getStudentYear(int id) returns int {
    string|error name = getName(id);
    if name is error {
        return -1;
    } else {
        int|error ret = getYear(name);
        if ret is error {
            return -1;
        } else {
            return ret;
        }
    }
}

//Helper functions
function getName(int id) returns string|error {
    return error("Student not found");
}

function getYear(string name) returns int|error {
    return error("Student year not found");
}

Good Code

function getStudentYear(int id) returns int|error {
    string name = check getName(id);
    return getYear(name);
}

//Helper functions
function getName(int id) returns string|error {
    return error("Student not found");
}

function getYear(string name) returns int|error {
    return error("Student year not found");
}

See Also:

• Error handling