Possible to add to constructor from property aspects?

[etkramer]

My goal is to give NotifyAttribute a parameter "dependsOn", which causes it to be notified any time some other property is changed - basically the reverse of AlsoNotify. To do this, my first instinct was to add something along the lines of

[Advice(Kind.After, Targets = Target.Constructor)]
public void AfterConstructor([Argument(Source.Instance)] object source, [Argument(Source.Name)] string propertyName, [Argument(Source.Triggers)] Attribute[] triggers)
{
    foreach (string dependencyProperty in triggers[0].DependsOn)
    {
        source.Subscribe(dependencyProperty, () => source.Raise(propertyName));
    }
}

However, this Advise doesn't actually seem to be triggered unless the aspect is applied directly to the class or the constructor - is there any way to have this be run used when the attribute is applied to a property instead?

[pamidur]

Hi @bitcrusader ,thanks for your interest in the project. You have an interesting idea here.

Let's consider this class

class Test
{
  [Notify]
  public string Name {get; set;}

  [Notify (DependsOn = nameof(Name) )]
  public string FirstName {get; set;}
}

In this case [Notify (DependsOn = nameof(Name) )] will only be triggered if FirstName is changed, but will not be triggered if Name is changed. As per docs

When you apply

[Notify (DependsOn = nameof(Name) )]
class Test
{
  [Notify]
  public string Name {get; set;}

  [Notify (DependsOn = nameof(Name) )]
  public string FirstName {get; set;}
}

you effectively doing this:

class Test
{
  [Notify]
  [Notify (DependsOn = nameof(Name) )]
  public string Name {get; set;}

  [Notify (DependsOn = nameof(Name) )]
  [Notify (DependsOn = nameof(Name) )]
  public string FirstName {get; set;}
}

but it still won't trigger Aspect on FirstName if Name is changed. But you might see behaviour where :

  [Notify (DependsOn = nameof(Name) )]
  public string Name {get; set;}

To solve it you might need to keep track on the dependencies in the class, but figure this dependencies on the first hit. Like the following:

• Advice is executed for Name
• You get all attributes of all properties of the class via reflection and figure which ones have DependsOn. Find FirstName
• Cache optionally
• Raise events for dependent properties

[pamidur]

If it already the case. And you just need to apply aspects to all properties, you might just want to have different attributes. Like this:

[Notifiable]
class Test
{
  [Notify]
  public string Name {get; set;}

  [Notify (DependsOn = nameof(Name) )]
  public string FirstName {get; set;}

  public string FirstName {get; set;}
}

so like this Aspect will be executed for all props and then you can raise events only for those having [Notify]