Rants about auto

kshegunov

@VRonin said in Why no std::byte in qt?!!:

Probably a better example is someFunction returns a QByteArray and people write QString ret = someFunction(); (I'm looking at you, QIODevice::readAll) even when they have no assurance the returned value is a UTF-8 encoded string. using auto would force ret to be QByteArray and it's also far more efficient.

I have only one thing to say here: QT_NO_CAST_FROM_ASCII ;)

@VRonin said in Why no std::byte in qt?!!:

I actually think it's a very smart way of handling and compressing intensive calculations, nevertheless now that auto is a thing users must be aware of this implementation detail more than ever

I agree on both counts.

JonB

My 2¢: when you have MyRidiculouslyLongClassNameWhichIDontWantToTypeInEachTimeSoIUseEvilAuto, try

typedef MyRidiculouslyLongClassNameWhichIDontWantToTypeInEachTimeSoIUseEvilAuto Z;

Z abc;

:)

VRonin

@JonB First of all using Z = MyRidiculouslyLongClassNameWhichIDontWantToTypeInEachTimeSoIUseEvilAuto; because C++11 :)

JonB

@VRonin
Sigh, looks like my C knowledge is increasingly invalid :( But I don't see what's wrong with typedef here, I'm not using a template.
BTW, I wouldn't really name it Z here, of course I'd use MRLCNWIDWTTIETSIUEA because it's much clearer what that means!

VRonin

@JonB said in Rants about auto:

But I don't see what's wrong with typedef here

Nothing, I was just taking the piss. they are equivalent with the only difference that the Z type can be a template with using while it can't with typedef.

JonB

@VRonin
Oh, lol! Once I started reading up about this new using I suspected that now I was supposed to use that every time....

With typedefs you can string them together for a nice extra level of confusion ;) So you write

typedef int I, *PI;

which makes me wonder: without you looking it up, if I write:

typedef int *PI, T;

is T type int or int *? :)

kshegunov

@JonB said in Rants about auto:

is T type int or int *?

int.
We are not JS devs, you know ... ;P

JonB

@kshegunov
Hmm. OK, then, could you please explain how the * binds in typedef int *PI, T;.

Why is that typedef not int * for T? And if you wanted it to bind as int * for T (i.e. making it same as PI), how could you force that, e.g. something like (I'm sure it's not right):

typedef (int *)PI, T

P.S.

We are not JS devs, you know

Ummm, relevance? JS doesn't even have type declarations or pointers, so...?

kshegunov

@JonB said in Rants about auto:

Why is that typedef not int * for T?

Not 100% about the theory behind it, but it's like with initialization (I assume it's cause , has very low priority). Say you have:

char * p, n;

p is char *, but n is char.

And if you wanted it to bind as int * for T (i.e. making it same as PI), how could you force that, e.g. something like (I'm sure it's not right):

typedef int *PI, *T;

Ummm, relevance? JS doesn't even have type declarations or pointers, so...?

Simply an ill-concealed insult. :)

PS:

Simply an ill-concealed insult.

https://www.destroyallsoftware.com/talks/wat

JonB

@kshegunov

typedef int *PI, *T;

That is cheating! You know it. You know that I know it can be done that way, that wasn't the question. I want the *s to be included in the "base" part of the typedef I am declaring, so that I can write like:

typedef (int **********) PI, PI2_same_as_PI, *PI3_one_extra_pointer;

I don't want to repeat the *s, and I don't want to declare a separate, intermediate typedef to achieve it.

As you say, thinking about the typedef just like a list-of-variables declaration, I guess it cannot be done? The *s just aren't a part of the "base" type being declared, they belong only to each type-name/variable being declared individually? And this is why we tend/are encouraged to write char *p and not char* p in C.

As for the JS. I know I am a cheerleader for C compared to C++, but I have never said I am a fanboi for all the JS stuff I have had to write over the years.

kshegunov

@JonB said in Rants about auto:

I don't want to repeat the *s, and I don't want to declare a separate, intermediate typedef to achieve it.

Then you're out of luck.

And this is why we tend/are encouraged to write

That's just style. I write spaces on both sides:

char * p;
char ** p;

and so on.

I know I am a cheerleader for C compared to C++

That's like being cheerleader for FORTRAN against C. ;)

but I have never said I am a fanboi for all the JS stuff I have had to write over the years.

Granted. I was just making fun of JS devs. ;P

JonB

@kshegunov
The declaration layout is just style, but I meant that char *p instead of char* p makes clear how C type declarations with * actually bind, relevant if you have a list of them (char *p, *q better than char* p, *q).

ODБOï

Hi,
@kshegunov said in Rants about auto:

https://www.destroyallsoftware.com/talks/wat

Can please someone tell me what environment is using Gary Bernhardt in that video ?

JonB

@LeLev
He is not using a special "environment" or IDE. He's just using a terminal/console, then running a Ruby/JS command-line interpreter which allows you type in statements to evaluate.

kshegunov

I believe it's zsh that he uses, otherwise Jon's right, he just starts the interpreters from the command line.

JonB

@kshegunov
And the relevance of it being specifically zsh is... what? :) You just looking for extra points? ;-)

kshegunov

@JonB said in Rants about auto:

And the relevance of it being specifically zsh is... what?

Environment of the interpreter.

You just looking for extra points?

Yep! Gimme, gimme!