Fluent Policy

Purpose

FluentPolicy offers a fluent syntax for creating policies concerning handling exceptions and return values from synchronous and asynchronous sources. It can be used to remove a lot of boilerplate code and allow methods to focus on what's actually relevant to them.

This library is heavily inspired by Polly. As Polly is much more mature solution I recommend using it, if the functionality offered is sufficient.

Installation

FluentPolicy is available on NuGet

Install-Package FluentPolicy -Version 1.0.2

Usage

Entry point to FluentPolicy is either a Func or Task for respectively synchronous or asynchronous mode of operations. To create a policy for them use WithPolicy extension methods. This will give you access to For() method that allows specifying conditions - either an exception that was thrown, or a return value was obtained and needs to be checked.

Specified conditions are checked top to bottom, and first matching one gets executed. Possible actions vary depending on whether the condition was exception or return value based. Available action are: Throw, Return, Rethrow (for exceptions only), Retry and WaitAndRetry (currently for exceptions only, but that's to be extended for return values as well).

Synchronous

From Func

Func<int> getInteger = () => 5;
var result = getInteger.WithPolicy()
            .For().Exception<MyCustomException>(mce=>mce.ErrorCode = 1).Return(-1)
            .For().Exception<MyCustomException>(mce=>mce.ErrorCode = 2).Return(-2)
            .For().Exception<MyCustomException>().Return(-3)
            .For().AllOtherExceptions().Rethrow()
            .Execute();

From Method

Unfortunatelly currently it is not possible to create an extension method for a method, so a helper is needed:

public int GetInteger(){
    return 5;
}
var result = As.Func(GetInteger).WithPolicy()
            .For().Exception<MyCustomException>(mce=>mce.ErrorCode = 1).Return(-1)
            .For().Exception<MyCustomException>(mce=>mce.ErrorCode = 2).Return(-2)
            .For().Exception<MyCustomException>().Return(-3)
            .For().AllOtherExceptions().Rethrow()
            .Execute();

Asynchronous

To use with asynchronous code just use WithAsyncPolicy and ExecuteAsync - rest of the methods stays the same

public async Task<int> GetIntegerAsync(){
	return await Task.FromResult(5);
}

var result = await As.Func(GetIntegerAsync).WithAsyncPolicy()
			.For().Exception<MyCustomException>(mce=>mce.ErrorCode = 1).Return(-1)
            .For().Exception<MyCustomException>(mce=>mce.ErrorCode = 2).Return(-2)
            .For().Exception<MyCustomException>().Return(-3)
            .For().AllOtherExceptions().Rethrow()
            .ExecuteAsync();