Re: Inner static puzzle
"Lew" <lew@lewscanon.nospam> wrote in message
news:A62dnVaMH-3OAibbnZ2dnUVZ_tSknZ2d@comcast.com...
Roedy Green wrote:
I have always wondered why static inner classes can have static
members but ordinary inner classes cannot. It seems a strange
anti-orthogonality.
Why? It would at first glance seem more work to treat them specially.
Is there some difficulty in implementation? Is there some reason why
stylistically the statics would be wicked?
I speculate it was to simplify notational cruft and difficulties of
implementation.
I've always been confused by whether a putative inner static would need an
enclosing instance, leading to weird notational idiomata:
new Foo().Bar.illegalStaticString = "";
or whether such a static would be static across all enclosing instances of
the inner class objects:
Foo.Bar.illegalStaticString = "";
Would a static inner-class method have access to any enclosing instance
attributes?
I suspect the choices matter at a low level in either the compiler or the
JVM and would've been difficult.
I disagree. I've always considered the restriction arbitrary, and think the
behavior is both clear and easy to implement. There's already a model for
its behavior: a local or anonymous class defined inside a static method of
the containing class. The resulting rules are:
1. Static members of an inner class would be truly static, that is, scoped
to the class rather than to an enclosing instance, and could be referenced
as Foo.Bar.member.
2. There is no enclosing instance inside a static method; attempts to
access instance methods of the containing class would be illegal.
And this all falls naturally out of the implementation.