Hiding class pointers -- was it a good idea?

[Bill Baxter]

Gregor Richards wrote:
> Bill Baxter wrote:
>> Gregor Richards wrote:
>>> #1 advantage of making them always by-value: Ridiculously 
>>> inconsistent use of by-value passing, ref passing and pointer passing.
>>>
>>> void foo(Thing a);
>>> void foo(ref Thing a);
>>> void foo(Thing *a);
>>>
>>> Wait, that's not an advantage at all, that's C++.
>>
>> I don't get your point.  Each of those things has different uses in C++.
>>
>> // if Thing is small/PoD and you don't want changes to affect caller
>> void foo(Thing a);
>>
>> // if Thing is bigger, you want to allow caller-visible changes, and 
>> you  require calling with non-null
>> void foo(ref Thing a);
>>
>> // same as above, but you want to allow null too
>> void foo(Thing *a);
>>
>>
>> The ref-can't-be-null thing may not hold for D, but it's true of C++.
>>
>> --bb
> 
> This just makes writing code more complicated. It's difficult to 
> remember whether some function wants a reference or a pointer, and you 
> have to be careful about how you treat them because they're 
> fundamentally different (see the operator overloading post). The 
> advantage is virtually nil, and it would create this huge complication. 
> That's why it's terrible in C++, and that's why it would be terrible in D.

D functions can also take pointers, values or references, so I don't see 
that D is really that different in this respect.  I guess you mean that, 
*if* you're talking about a class type, then you can be pretty certain 
you won't need to call a function using a derefernce like 
foo(&theThing).  Yeh, I guess that is a positive point of hiding 
pointers.  Of course it comes at the expense of making it impossible to 
pass a class by value.  You could also just outlaw pass-by-value for 
classes, and automatically dereference any value classes passed to 
functions expecting a class pointer.  So I don't think it's strictly 
necessary to hide the pointer in order to get this benefit you speak of.

--bb