ballerina 学习十六 错误&&异常处理
ballerina 的error 处理和elxiir 以及rust 比较类似使用模式匹配，但是他的 error lifting 还是比较方便的
同时check 也挺好，异常处理没什么特殊的 throw 以及 throw catch finally
简单例子
- error-handling
import ballerina/io;
function getAccountBalance(int accountID) returns (int|error) {
if (accountID < 100) {
error err = { message: "Account with ID: " + accountID +
" is not found" };
return err;
} else {
return 600;
}
}
function main(string… args) {
var r = getAccountBalance(24);
match r {
int blnc => {
io:println(blnc);
}
error err => {
io:println("Error occurred: " + err.message);
}
}
}- error lifting
import ballerina/io;
type Response {
Status|error status;
};
type Status {
string message;
int code;
};
function main(string… args) {
error e = { message: "response error" };
Response|error firstResponse = e;
int|error statusCode1 = firstResponse!status!code;
io:println("The status code: ", statusCode1);
Response|error|() secondResponse = ();
int|error|() statusCode2 = secondResponse!status!code;
io:println("The status code: ", statusCode2);
}- check
import ballerina/io;
type Person {
string name;
Address? address;
};
type Address {
string street;
string city;
};
function getAddress(Person p) returns (Address|error) {
match (p.address) {
Address add => { return add;}
() => {
error addNotFoundErr = { message: "address not found" };
return addNotFoundErr;
}
}
}
function validateAddress(Person person) returns (boolean|error) {
string city = check getAddress(person)!city;
io:println(, " has a valid city");
return true;
}
function validateAddressAgain(Person person) returns boolean {
string city = check getAddress(person)!city;
io:println(, " has a valid city");
return true;
}
function main(string… args) {
Person bob = { name: "bob" };
Address address = { street: "1st Avenue", city: "Manhattan" };
bob.address = address;
io:println("validating bob…");
var bobResult1 = validateAddress(bob);
io:println("Bob's result 1:", bobResult1);
boolean bobResult2 = validateAddressAgain(bob);
io:println("Bob's result 2:", bobResult2);
Person tom = { name: "tom" };
io:println("\n", "validating tom…");
var tomResult1 = validateAddress(tom);
io:println("Tom's result 1:", tomResult1);
var tomResult2 = validateAddressAgain(tom);
io:println("Tom's result 2:", tomResult2);
}
- throw
import ballerina/io;
type Record {
int id;
string name;
};
function readRecord(Record|() value) {
match value {
Record rec => {
io:println("Record ID: ", rec.id, ", value: ", );
}
(any|()) => {
error err = { message: "Record is null" };
throw err;
}
}
}
function main(string… args) {
Record r1 = { id: 1, name: "record1" };
readRecord(r1);
Record|() r2;
match r2 {
Record rec => {
io:println("Record: " + );
}
(any|()) => {
readRecord(r2);
}
}
Record r3 = { id: 3, name: "record3" };
readRecord(r3);
}- thorw/catch/finally
import ballerina/log;
import ballerina/runtime;
import ballerina/io;
function main(string… args) {
int result;
try {
io:println("Start dividing numbers");
result = divideNumbers(1, 0);
} catch (error err) {
io:println("Error occurred: ", err.message);
} finally {
io:println("Finally block executed");
}
}
function divideNumbers(int a, int b) returns int {
return a / b;
}
