Crank.Result

Crank result are a set of slightly opinionated result classes.

Result

• Contains a Succeeded, Failed and an optional Message value.
• Failed == !Succeeded

Setting the result:

Assignment:

Result result = true;

Tuple Assignment:

Result result = (true, "Success message"); Result result = (false, "Failure message");

Static Methods:

Result result = Result.Success(); Result result = Result.Fail(); Result result = Result.Fail("Failure message");

Result< int> result = Result.Fail< int>(404, "Failure message"); // note: fails up to Result< TPrimaryValue> from Result

Checking success:

If (result == true) ... If (result.Succeeded) ... If (!result.Failed) ...

Extracting values:

var errorMessage = result.Message; var (succeeded, message) = result;

// Return false and default as Result has no value bool haveValue = result.TryGetValue(out int? value); int? value = result.As();

Result< TPrimaryValue >

• inherits from Result
• TPrimaryValue is accessible from the Value member
• opinionated: when directly assigning a TPrimaryValue value, infers success == true

Setting the result:

Assignment:

Result< Guid> result = Guid.NewGuid();
// side effect: set Succeeded to true

Tuple Assignment:

Result< Guid> result = (succeeded, Guid.NewGuid()); Result< Guid> result = (succeeded, Guid.NewGuid(), "Error Message");

Static Methods:

Result< Guid> result = Result< Guid>.Success(Guid.NewGuid()); Result< Guid> result = Result< Guid>.Fail(value: Guid.NewGuid(), message: "Error message");

Result< Guid, int> result = Result.Fail< int>(404, "Failure message"); // note: fails up to Result<TPrimaryResult, TSecondaryResult> from Result< TPrimaryResult>

Checking success:

If (result == true) ... If (result.Succeeded) ... If (!result.Failed) ...

Extracting values:

Guid id = result.Value; Guid id = result; var (succeeded, guidValue) = result; var (succeeded, guidValue, message) = result;

bool haveValue = result.TryGetValue< Guid>(out Guid? value); Guid? value = result.As< Guid>();

[v1.2] Deref

deconstruct reference type without nullable inference var (succeeded, value, message) = result.Deref(); notes: if value is null, succeeded will be destructed as false equivant of: succeeded = (succeeded && value != null) can change this behaviour by calling Deref(false)

Result< TPrimaryValue, TSecondaryValue >

• inherits from Result< TPrimaryValue>
• Assignable to TResult< TPrimaryValue> where both TPrimaryValues are the same type -- opinionated: TSecondaryValue is accessible from the Value member (instead of TPrimaryValue) -- opinionated: when directly assigning a TSecondaryValue value, infers success == false

Setting the result:

Assignment:

Result< Guid, int> result = 404; // side effect: set Succeeded to false

Tuple Assignment:

Result< Guid, int> result = (404, "Failure message"); Result< Guid, int> result = (succeeded, 404, "Failure message");

Static Methods:

Result< Guid, int>.Fail(value: Guid.NewGuid(), message: "Error message");

Checking success:

If (result == true) ... If (result.Succeeded) ... If (!result.Failed) ...

Extracting Values

int errorCode = result.Value; int errorCode = result; var (succeeded, intValue) = result; var (succeeded, intValue, message) = result;

bool haveValue = result.TryGetValue< int>(out int? value); int? value = result.As< int>();

[v1.2] Deref

deconstruct reference type without nullable inference var (succeeded, value, message) = result.Deref();

Setting and extracting both values

Result<Guid, int> result = (true, Guid.NewGuid(), 200, "Success Message"); (succeeded, primaryValue, secondaryValue) = result; (succeeded, primaryValue, secondaryValue, message) = result;

Common usage examples

Returning a result with an error message

public Result InvokeOperation()
{
	try
	{
		_repository.Invoke();
		return true;
	}
	catch (Exception ex)
	{
		return (false, ex.Message);
	}
} 

Returning success or additional error data

public Result InvokeOperation
{
	try
	{
		int resultCode = _repository.Invoke();
		if (resultCode > 0)
			return true;

		// fail up to Result<TPrimary>
		return Result.Fail(resultCode);
	}
	catch (Exception ex)
	{
		// fail up to Result<TPrimary>
		return Result.Fail(ex);
	}
}

Return success data or failure

public Result<IEnumerable<RowData>> LoadRowData(string filename)
{
	try
	{
		var data = _repository.LoadData(filename);
		return data;
	}
	catch (Exception ex)
	{
		// fail up to Result<TPrimary, TSecondary>
		return Result<IEnumerable<RowData>>.Fail(ex);
	}
}

Differentiating between different result types

var result = LoadRowData();
if (result.Succeeded) // happy case
	return Ok(result.Value);

if (result is Result<IEnumerable<RowData>, int> errorResult)
	return ErrorResult(new { errorCode = errorResult.Value });

if (result is Result<IEnumerable<RowData>, Exception> exceptionResult)
	return InternalServerError();

...	alterative

var result = LoadRowData();
if (result.Succeeded) ...

if (result.TryGetValue<int>(out int errorCode))
	return ErrorResult(new { errorCode });

if (result.TryGetValue<Exception>(out Exception _))
	return InternalServerError();

Change Logs

[1.0] Initial release

[1.1] Added NotNull property and tests

[1.2] Removed NotNull property and tests Added Deref Result extensions methods and tests