undefined | Better HN

0 pointsAnimalMuppet2y ago0 comments

> There are thing that cannot be even named.

Um, can you give me an example? (Can you give an example without naming it?)

Types that cannot be written, or are too long to be reasonably written, are likely to also be too hard to really understand. Maybe their existence should be regarded as a code smell.

0 comments

germandiago2y ago

The type of a lambda cannot be spelled. The type of a local class return cannot be named from outside either.

AnimalMuppetOP2y ago

By "local class return", do you mean a function that returns what Java calls an "inner class"? That's perfectly describable (in C++ as well) if the inner class is public rather than private. It's unnameable, not because of the type, but because of the access (private).

germandiago2y ago

You can create a class inside a function and return an object of it. That name is not legal outside of the function but its methods can be called.

AnimalMuppetOP2y ago

Ah, I see. Inner to the function, not inner to the class. So the C++ syntax would need to be something like:

  ClassName::functionName::innerName

Except that's not an actual C++ syntax - there isn't one.

But if you return it from a function, how do you declare the variable you assign it to? auto?

And, is auto a valid return type from a function? If not, how do you declare the function that returns this object?

1 more reply

j / k navigate · click thread line to collapse

0 comments

germandiago2y ago

The type of a lambda cannot be spelled. The type of a local class return cannot be named from outside either.

AnimalMuppetOP2y ago

germandiago2y ago

You can create a class inside a function and return an object of it. That name is not legal outside of the function but its methods can be called.

AnimalMuppetOP2y ago

Ah, I see. Inner to the function, not inner to the class. So the C++ syntax would need to be something like:

  ClassName::functionName::innerName

Except that's not an actual C++ syntax - there isn't one.

But if you return it from a function, how do you declare the variable you assign it to? auto?

And, is auto a valid return type from a function? If not, how do you declare the function that returns this object?

1 more reply

j / k navigate · click thread line to collapse