ceylon.language.meta.declaration.ValueDeclaration.ceylon Maven / Gradle / Ivy

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import ceylon.language.meta.model { 
    Value, 
    Attribute, 
    AppliedType = Type, 
    IncompatibleTypeException, 
    StorageException 
}

"""A value declaration.
   
   
   ### Usage sample for toplevel value
   
   Getting a model requires applying type arguments to the
   value declaration with [[apply]] in order to be able to read that value. For example, here is how you would
   obtain a value model that you can read from a toplevel attribute declaration:
   
       String foo = "Hello";
       
       void test(){
           // We need to apply the the foo declaration in order to get the foo value model
           Value valueModel = `value foo`.apply();
           // This will print: Hello
           print(valueModel.get());
       }
   
   
   ### Usage sample for attributes
	
   For attributes it is a bit longer, because attributes need to be applied the containing type, so you should 
   use [[memberApply]] and start by giving the containing closed type:
   
       class Outer(){
           shared String foo => "Hello";
       }
	
       void test(){
           // Apply the containing closed type `Outer` to the attribute declaration `Outer.foo`
           Attribute valueModel = `value Outer.foo`.memberApply(`Outer`);
           // We now have an Attribute, which needs to be applied to a containing instance in order to become a
           // readable value:
           Value boundValueModel = valueModel(Outer());
           // This will print: Hello
           print(boundValueModel.get());
       }
   """
shared sealed interface ValueDeclaration
        satisfies FunctionOrValueDeclaration & GettableDeclaration {
    
    "True if this declaration is annotated with [[late|ceylon.language::late]]."
    since("1.2.0")
    shared formal Boolean late;
    
    "True if this declaration is annotated with [[variable|ceylon.language::variable]]."
    shared formal Boolean variable;

    "True if this declaration is an `object` declaration, whose type is an anonymous class."
    since("1.1.0")
    shared formal Boolean objectValue;
    
    "This value's anonymous class declaration if this value is an object declaration. `null` otherwise."
    since("1.1.0")
    shared formal ClassDeclaration? objectClass;

    "Applies this value declaration in order to obtain a value model. 
     See [this code sample](#toplevel-sample) for an example on how to use this."
    throws(`class IncompatibleTypeException`, "If the specified `Get` or `Set` type arguments are not compatible with the actual result.")
    shared formal Value apply();
    
    "Applies this `static` value declaration in order to obtain a value model."
    throws(`class IncompatibleTypeException`, "If the specified `Get` or `Set` type arguments are not compatible with the actual result.")
    shared formal Value staticApply(AppliedType