Method calls vs lambda calls

[Neal Gafter]

On Wed, Dec 16, 2009 at 11:10 AM, Stefan Schulz <schulz at the-loom.de> wrote:

> Neal Gafter wrote:
>
>> On Wed, Dec 16, 2009 at 6:36 AM, Stefan Schulz <schulz at the-loom.de
>> <mailto:schulz at the-loom.de>> wrote:
>>    I didn't say anything about making a method. If the short-hand
>>    invocation syntax is allowed, putting names of function-typed variables
>>    in the same (scope-relative) space like methods is a way to ensure not
>>    to have methods and function-typed variables with the same name.
>>
>> I'm afraid it doesn't ensure that at all.  Because methods may overload,
>> a given scope may have many definitions for a given name in the method
>> namespace.
>>
>
> Too bad. Is there any possibility to hold the full signature of methods and
> function-typed variables in some way to being able to resolve these
> conflicts? Maybe an additional function space? Sorry, if this sounds a bit
> naive.


I'm not sure what you're asking.  The mechanism for resolving these
conflicts today is (compile-time) overload resolution.  It would have to be
extended to handle the case of a mixture of methods and variables of
function type.


>     As this
>>    has to hold for inheritance, too, I do not see a problem in
>>    function-typed variables of subclasses to @Override those of a
>>    superclass, as the information is already there. (Of course, they must
>>    additionally hide normal variables having the same name.)
>>
>>
>> What semantics are you imagining for this overriding?  What if the thing
>> being overridden is a method?
>>
>
> I didn't mean to being able to override methods with function-typed
> variables, or vice versa (although this sounds interesting).
>
> So, what would be the conclusion?
> * If any method m exists in a class's hierarchy, one cannot define a
> function-typed field m?
> * If a function-typed field m exists in a class's hierarchy, one cannot
> define a method named m?
> * If a function-typed field m exists in a class's hierarchy, will a field
> named m (of any type?) in a subclass hide the function-typed field m?
> * If a non-function-typed field m hides a superclass's function-typed field
> m, would it be possible to define a method named m in that very subclass?


Good questions, and there are many more.  Function-typed variables can be
declared as local variables and parameters too.  They can also have a type
of a generic parameter in a superclass but be inherited into a subclass as a
function type:

*class Base<T> { T t; int t(int x) { return x; } }
class Derived: Base<#int(int)> {}
*

if Derived.t in the function namespace?

A complete specification must provide clear answers to all these questions.

Cheers,
Neal