[Development] RFC: more liberal 'auto' rules?

[Bubke Marco]

On December 4, 2015 16:10:56 Rafael Roquetto <rafael.roquetto at kdab.com> wrote:

> On Fri, Dec 04, 2015 at 02:25:14PM +0100, Olivier Goffart wrote:
>> On Friday 4. December 2015 14:11:48 Oswald Buddenhagen wrote:
>> > On Fri, Dec 04, 2015 at 02:07:10PM +0100, Marc Mutz wrote:
>> > > And as an aside, since it has been mentioned in this thread: in Python
>> > > _all_ variables are 'auto'. All. Without exception. Are Python
>> > > programmers more intelligent? Or do they just tolerate more pain? :)
>> > 
>> > i'd suggest the latter.
>> > no, really. people use external static checkers because the language
>> > lacks the feature.
>> > the lack of static typing is a common feature of scripting languages and
>> > makes them convenient to a degree, but it is an utter nightmare for any
>> > "real" software development. i really wouldn't want to go there.
>> 
>> But auto is still staticaly typed.
>> 
>> 
>> When you have code like
>> 
>>    foo->bar()->setFaz(m_factory->createFaz(foo->bar()->type()));
>> 
>> You don't see any type. 
>> 
>> This code that use auto is not less readable. Even if you don't know what's 
>> the type of bar without looking it up.
>> 
>>   auto *bar = foo->bar();
>>   bar->setFaz(m_factory->createFaz(bar->type()));
>
> Until you need to change your code and call any method of bar. Suppose I
> need to change the following code, to print the first item of the collection:
>
>     auto *bar = foo->collection();
>
>     /*TODO: print first item here */
>
>     model->setCollection(bar); // we know bar is a collection, but of what kind?
>
>
> Choose the right alternative:
>
>     a) qDebug() << bar->first();
>     b) qDebug() << bar->values().first();
>     c) qDebug() << bar[0]
>     d) none of the above
>
>
> To answer this, you will need to find out the return type of
> Foo::collection(); The compiler knows it, but the reader does not. And the
> answer depends on whether it is  a QList/QVector, QHash/QMap, etc... Had it
> been explicit, any programmer familiar with the Qt API (or any API in context)
> would be able to directly write down the right statement.
>

The clang code model completes auto so it should be not that hard.  Actually I would call an ordered map or unordered map a dictionary. 
>
> Just an idea.
>
> Cheers,
> Rafael
>
> -- 
> Rafael Roquetto | rafael.roquetto at kdab.com | Software Engineer
> Klarälvdalens Datakonsult AB, a KDAB Group company
> Tel. Sweden (HQ) +46-563-540090, USA +1-866-777-KDAB(5322)
> KDAB - Qt Experts
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