[CAUSEWAY-1998] Simplify syntax way for mixins, to better express intent using @Action, @Collection and @Property

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Implemented
• Affects Version/s: 1.16.2
• Fix Version/s: 2.0.0-M3
• Assignee: Andi Huber
• Reporter: Daniel Keir Haywood
• Created: 29/Sep/18 13:36
• Updated: 30/Mar/20 08:31
• Resolved: 12/Dec/19 11:31

Description

For regular action mixins, we currently write:

 

@Mixin(method="act")
public class Contributee_someAction() {

    private final Contributee contributee;  // constructor omitted
    @Action(...)
    @ActionLayout(...)
    public ReturnValue act(.... ) { ... }
}

instead, the proposal is:

@Action(...)              // presence of Action on class implies this is a mixin; 
@ActionLayout(...)
public class Contributee_someAction() {
    private final Contributee contributee;
    public ReturnValue act( ... ) { ... }   // no need for annotations here.   "act" assumed
}

The details of the @Action and @ActionLayout facets are "copied" down to the "act" method.

for properties, we currently write:

@Mixin(method="prop")
public class Contributee_someProperty() {
    private final Contributee contributee;  
    @Action(semantics=SAFE)   // required
    @ActionLayout(contributed=ASSOCIATION)  // required
    @Property(...)
    @PropertyLayout(...)
    public ReturnValue prop( /* no args */ ) { ... }
}

instead we'd rather write:

@Property(...)     // implies this class is a mixin
@PropertyLayout(...)
public class Contributee_someProperty()
    private final Contributee contributee;
    public ReturnValue prop() { ... }                    // "prop" is assumed
}

The boilerplate (and confusing) @Action(SAFE) and @ActionLayout(AS_ASSOCIATION) are implied. The facets from @Property and @PropertyLayout are copied down to the "prop" method

And finally, for collections, we currently write:

@Mixin(method="coll")
public class Contributee_someCollection() {
    private final Contributee contributee;  
    @Action(semantics=SAFE)   // required
    @ActionLayout(contributed=ASSOCIATION)  // required
    @Collection(...)
    @CollectionLayout(...)
    public List<ReturnValue> coll( /* no args */ ) { ... }
}

instead we'd rather write:

@Collection(...)     // implies this class is a mixin
@CollectionLayout(...)
public class Contributee_someCollection()
    private final Contributee contributee;
    public List<ReturnValue> coll() { ... }                    // "coll" is assumed
}

similar to properties.

Issue Links

• is related to: CAUSEWAY-2318 [CANNOT REPRODUCE] Regression on Mixins: @Action at method level no longer honor association
• is related to: CAUSEWAY-2335 Mixins declared using type-level @Action should not contribute as Association