MicroKnights.ConditionalFeature 1.1.0

What is ConditionalFeature

How do i get started?

Inherit one of the ConditionalFeatures;

• BooleanConditionalFeature

• EnumConditionalFeature

• DateTimeConditionFeature

  or make your own simple and easy

Three approaches can be used to implement a ConditionalFeature.

• Set the value directly on instantiating, or override ResolveFeatureValue().
• Provide a Func. This will be called every time the ConditionalFeature is queried. The Func controls the thread safety.
• Provide a Lazy. This will be called only once, first time the ConditionalFeature is queried. The value will be cached for future queries. This one is thread safe.

Use only one of the listed approaches

// Using static value
public class ShowDiagnosticsFeature : BooleanConditionalFeature
{
    public ShowDiagnosticsFeature()
        : base(true)
    {}
}

var featureDiagnostics = new ShowDiagnosticsFeature();
if( featureDiagnostics.IsEnabled ) {
    // do enabled stuff...
}
...
if( featureDiagnostics.IsDisabled ) {
    // do disabled stuff...
}
...    
featureDiagnostics.OnEnabled( () => {
    // do enabled stuff...
});
featureDiagnostics.OnDisabled( () => {
    // do disabled stuff...
});

or

// Using Func, will be evaluated every time the ConditionalFeature is queried
public class GodUserFeature : BooleanConditionalFeature
{
    public GodUserFeature(Func<bool> func)
        : base(func)
    {}
}

var godUser = new GodUserFeature(() => {
    var identity = Thread.CurrentPrincipal.Identity;
    return identity.IsAuthenticated && identity.Name.ToLowerInvariant() == "me";
});
if( godUser.IsEnabled ) {
    // do god stuff...
}

or

// Using Lazy, that is  called once on first hit.    
public class LicenseFeature : BooleanConditionalFeature
{
    public LicenseFeature(Lazy<bool> lazy)
        : base(lazy,false)
    {}
}

var license = new LicenseFeature( new Lazy<bool>( () => {
    var licenseLines = File.ReadAllLines("license.txt")
    return licenseLines.Any(l=>l == "payed:true" );
});
if( license.IsEnabled ) {
    // Full throttle...
}

Recommends use of DependencyInjection to request you ConditionalFeatures through out your application.

Where can I get it?

PM> Install-Package MicroKnights.ConditionalFeature

See also Package MicroKnights.ConditionalFeature.Configuration for using appsettings.config to configure the ConditionalFeatures.

Test / Samples

Look in the Test project for more samples, including EnumConditionalFeature and DateTimeConditionalFeature!

ConditionalFeature is Copyright © 2017 MicroKnights / Frank Løvendahl Nielsen and is entirely free to use.