Question

My code looks ugly, and I know there’s got to be a better way of doing what I’m doing:

private delegate string doStuff(
    PasswordEncrypter encrypter, RSAPublicKey publicKey,
    string privateKey, out string salt
);

private bool tryEncryptPassword(
    doStuff encryptPassword,
    out string errorMessage
)
{
    ...get some variables...
    string encryptedPassword = encryptPassword(encrypter, publicKey,
        privateKey, out salt);
    ...
}

This stuff so far doesn’t bother me. It’s how I’m calling tryEncryptPassword that looks so ugly, and has duplication because I call it from two methods:

public bool method1(out string errorMessage)
{
    string rawPassword = "foo";
    return tryEncryptPassword(
        (PasswordEncrypter encrypter, RSAPublicKey publicKey,
            string privateKey, out string salt) =>
            encrypter.EncryptPasswordAndDoStuff( // Overload 1
                rawPassword, publicKey, privateKey, out salt
            ),
        out errorMessage
    );
}

public bool method2(SecureString unencryptedPassword,
    out string errorMessage)
{
    return tryEncryptPassword(
       (PasswordEncrypter encrypter, RSAPublicKey publicKey,
           string privateKey, out string salt) =>
           encrypter.EncryptPasswordAndDoStuff( // Overload 2
               unencryptedPassword, publicKey, privateKey, out salt
           ),
       out errorMessage
   );
}

Two parts to the ugliness:

• I have to explicitly list all the parameter types in the lambda expression because of the single out parameter.
• The two overloads of EncryptPasswordAndDoStuff take all the same parameters except for the first parameter, which can either be a string or a SecureString. So method1 and method2 are pretty much identical, they just call different overloads of EncryptPasswordAndDoStuff.

Any suggestions?

Edit (solution): I ended up using Jeff’s suggestion and altering the overloads of EncryptPasswordAndDoStuff to return an instance of EncryptionResult. Then I didn’t need an explicitly defined delegate, and I used the following code:

private bool tryEncryptPassword(KeysAndEncrypter keys,
    Func<EncryptionResult> encryptPassword,
    out string errorMessage
) { ... }

private class KeysAndEncrypter
{
    public RSAPublicKey PublicKey { get; set; }
    public string PrivateKey { get; set; }
    public PasswordEncrypter Encrypter { get; set; }
}

And here was the contents of method1, with method2 being very similar:

string rawPassword = "foo";
KeysAndEncrypter keys = getEncryptionKeys();
return tryEncryptPassword(keys, () =>
    keys.Encrypter.EncryptPasswordAndDoStuff(
        rawPassword, keys.PublicKey, keys.PrivateKey
    ),
    out errorMessage
);

Answer 1

You could introduce a new type to represent the delegate’s return value:

 public class EncryptionResult {
     public string EncryptedValue { get; set; }
     public string Salt { get; set; }
 }

… and change the delegate to something like this:

 private delegate EncryptionResult doStuff(
     PasswordEncrypter encrypter, 
     RSAPublicKey publicKey,
     string privateKey);