Re: [9fans] useful language extension, or no?

[forsyth@vitanuova.com]

>>Why was it worthwhile to change the language in this respect,
>>for the idiom of "always having to make sure the lock is the
>>first item in the structure for pointer coersion is a pain?"

because with ken's extension, it needn't be the first element,
and it provides type checking that would be suppressed
by the explicit cast required for the `first item' approach.

in the case of Lock, it's easy to see that we could do without:

	typedef struct Thing Thing;
	struct Thing{
		int	a;
		Lock	l;
	};

just requires
	lock(&t->l);
instead of
	lock(t);
as in Plan 9.

the advantage of the latter, however, is that it is clear and readable,
not that it saves typing.  in fact it does save typing, but that's
a side effect.

it's also a little more subtle in the case of bio (say).

in fact, C provides just what you want to save the ugly
extra comparison: functions with early return.

>>You're going to have to do better than that.  Simply
>>pulling the 'ole "I'm overly negative and as a result most
>>people avoid confrontation with me" isn't going to cut it.

overly negative?  surely no one negative and pessimistic
would bother to start thinking about writing a system, let
alone actually doing it.   surely doing something constructive
is a truly positive act!