standards-c-sharp

Only throw exceptions in exceptional circumstances

• Exceptional: the database went down. This is exceptional because in general we expect databases to stay up.
• Not exceptional: the user entered an incorrect password. This is not exceptional because users are expected to typo their password at least 23 times a day.
• Or, to put it another way, do not use exceptions for control flow. When used like this, they are effectively GOTO statements and make the code harder to read.

Don’t

try
{
    _authenticationService.LogUserIn(username, password);
}
catch (InvalidCredentialsException)
{
    // show "Invalid credentials" message
}

Do

var authResult = _authenticationService.LogUserIn(username, password);
// instead of using an exception to indicate (expected) failure, we use a control statement
if (!authResult.IsAuthenticated) 
{
    // show "Invalid credentials" message
}

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