Property hooks with attribute

[Cologler]

Currently, property hook work like:

[Notify] private string _firstName;
[Notify] private string _lastName;
[Notify] private string _fullName;

void OnFirstNameChanged() => this.UpdateFullName();
void OnLastNameChanged() => this.UpdateFullName();
void UpdateFullName() => ...

If the FullName depends on more properties, the On{PropertyName}Changed() list may grow unnecessary.

And the property hook is hard to detect errors in compile-time if we try to rename the _firstName.

What if we can use attributes, it can be:

[Notify][PropertyChangedHook(nameof(UpdateFullName))] private string _firstName;
[Notify][PropertyChangedHook(nameof(UpdateFullName))] private string _lastName;
[Notify]private string _fullName;

void UpdateFullName() => ...

[Cologler]

@canton7

[canton7]

Sorry, real life is taking a bunch of my time.

Possible -- it wouldn't be that hard to add, but I might question the need.

In this specific case, wouldn't it make more sense to write it as:

[Notify] private string _firstName;
[Notify] private string _lastName;
public string FullName => $"{_firstName} {_lastName}";

That uses the automatic property dependency stuff, and a PropertyChanged event for FullName will be raised whenever FirstName or LastName changes. If you need to use a method to generate the value for FullName, you can do:

[Notify] private string _firstName;
[Notify] private string _lastName;
[DependsOn(nameof(FullName), nameof(LastName))] public string FullName => CreateFullName();

(or the equivalent using AlsoNotify).

These both have the advantage of letting FullName say what it depends on, rather than forcing you to manually keep track of this.

The downside is that you don't cache the value of FullName and it's re-calculated on each access, but I'd love to see a case where that actually mattered!

[Cologler]

Don't need to apologize, real life is more important.

Unlink the FullName is a property, here is a partial code of my real-world project:

        private void UpdateExpirationsEnd()
        {
            ...
        }

        private void OnExpirationsStartChanged() => this.UpdateExpirationsEnd();

        private void OnExpirationsSelectedTimeSpanChanged() => this.UpdateExpirationsEnd();

        private void OnExpirationsTimeSpanUnitSelectedItemChanged() => this.UpdateExpirationsEnd();

Since the UpdateExpirationsEnd() is not a property, it seems to be unable to use the [AlsoNotify] attribute.

[canton7]

Fair enough. I can't promise when I'll get time to look at this, it might be a few weeks.

If you fancy having a crack yourself, OnPropertyNameChanged will need to change to a List<OnPropertyNameChangedInfo>, and FindPropertyNameChangedMethod updated to find multiple methods to call, using a new attribute.

For the attribute name, I'm not sure whether to go with your PropertyChangedHook (which does match the wording in the README), or something like OnChanged...

[Cologler]

How about [AlsoCall] or allow [DependsOn] to add to the method?