assignment: left-to-right or right-to-left evaluation?

[Georg Wrede]

Andrei Alexandrescu wrote:
> Georg Wrede wrote:
>> If the programmer has introduced dependencies on the evaluation order, 
>> yes. But if he hasn't, then it will not introduce anything.
> 
> If violations could be checked such that invalid code is rejected, your 
> solution would work.
> 
>> With
>>
>>   a[fun] = gun;
>>
>> a rewrite
>>
>>   auto f = a[fun];
>>   a[f] = gun;
>>
>> makes it explicit how the programmer wants it done. It also removes 
>> any uncertainty (and need to remember an arbitrary rule) for other 
>> people.
>>
>> If you'd really want things easy for Walter, unambiguous, and clear 
>> for the reader, then you'd advocate forbidding expressions in lvalues.
> 
> I think that would be too restrictive. a[b] is already an expression.

I guessed you'd say that. But I thought it'd be condescending to explain 
that the compiler should notice a leaf expression.

> The solution is simple: define an order of evaluation such that even bad 
> code behaves consistently.

Then pick lexical order. For consistency, that's what statement.html has 
all over the place anyway.