Default method survey results

Maurizio Cimadamore maurizio.cimadamore at
Thu Aug 16 02:47:16 PDT 2012

On 16/08/12 10:13, Alex Blewitt wrote:
> The point of confusion - where the method is coming from - is at use 
> site of the interface, not declaration site. What keywords you use at 
> the declaration site (probably written by someone else) will make 
> absolutely no difference to the person who implements that interface, 
> keyword or not.
How do you get to know the set of methods that have to be implemented 
when you implement an interface? Probably you go and look at the Javadoc 
for that interface. Then you see a list of methods, some of which have 
the D-word; you know that, at the very least (i.e. not to get 
compile-time errors) you have to implement all the remaining ones (w/o 
the D-word).

But I think we are a bit down into a syntactic rat-hole here - the 
original question was - why not allowing a third option in the survey, 
one that mandates no keywords at all to denote an 'interface method with 
body'. The motivations behind the choice were several, including:

*) 'default' will make the interface code easier to parse

*) a keyword will provide an handy 1-1 mapping between source code and 

*) 'default' is the dual of 'abstract' - it must be specified in 
interfaces the same way as 'abstract' must be specified in classes

*) the presence of a keyword will help extending the syntax even more by 
adding new default forms

*) 'default' summarises the semantics pretty well

What are the motivations behind leaving the 'default' keyword out? Note: 
it must be more than just avoiding to type 'd' 'e' 'f' 'a' 'u' 'l' 't' - 
which, as you say, probably somebody else would have typed in for you ;-)


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