D's "accessors" are like abusing operator overloads

[Denis Koroskin]

On Fri, 27 Mar 2009 18:53:51 +0300, BCS <none at anon.com> wrote:

> Hello Nick,
>
>> I don't mean to put words in the Tango crew's mouths, but IMO this
>> piece from 0.99.8's changelog is a great demonstration of what's wrong
>> with D's sloppy "accessor" syntax:
>>
>> -------------
>> tango.time
>> * TimeSpan.seconds(ulong), etc. is now replaced by
>> TimeSpan.fromSeconds(ulong), etc. The original form causes problems
>> when people write code like:
>>
>> auto ts = TimeSpan.seconds(60);
>> ts.seconds = 30; // you would think this would assign 30 seconds to
>> ts, but
>> what it does is create a
>> // temporary and throw it away.
>> -------------
>> The fact that D lets you freely switch between "foo(x)" and "foo = x"
>> (at least when you're not using a return value from foo) implies that
>> passing one argument to a function is, in the general case,
>> conceptually related to assigning a value. And that is an absurdity
>> and abuse of syntax on the same level as pretending that string
>> concatenation is an "addition" or that outputting is a "<<", etc.
>>
>> And this "solution" that Tango was forced to use as a result of that
>> kludge doesn't totally solve the problem since it leaves symantic
>> gibberish like this as perfectly-compileable:
>>
>> ts.fromSeconds = 30; // WTF is that supposed to mean?!? But it
>> compiles anyway!
>>
>
> One option would be to only allow that fn = v syntax where fn returns void.
>
>

Obscure rule and a bad idea in general. This way you can't do "a = b = c = 42;"-style chaining.