What are the details of this struct inheriting from a template?

Asked Apr 30 '19 at 12:18

Active Apr 30 '19 at 12:18

Viewed 27 times

0

In declarations, one can turn a c++ statement into words.

int a;  // a is declared an integer

I don't understand what the words are for the declaration below.

A is declared as a struct...?

struct A : public aTemplate<A> {};

I also don't understand how A can be used in two places.

asked Apr 30 '19 at 12:18

KeithSmith

774
2
8
26

TBH I don't have the slightest clue what you're asking about. Unless you're asking about the [CRTP](https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern). – πάντα ῥεῖ Apr 30 '19 at 12:22
"I also don't understand how `A` can be used in two places." `A` is a type, so it would be like asking how can `int` appear in more than one place. – Federico klez Culloca Apr 30 '19 at 12:22
1

`struct A` says that `A` is the name of a `struct`; that makes it the name of a type. `aTemplate` says to instantiate the template `aTemplate` with the type `A`, just as `aTemplate` says to instantiate `aTemplate` with the type `int`. – Pete Becker Apr 30 '19 at 12:24
1

its a struct called `A` that inherits from `aTemplate`, ie a template called `aTemplate` instantiated for the template parameter `A`, ie the struct itself. Consider `struct node { node* left,right; }` as just another example, where the class of the name is "used in two places" – 463035818_is_not_an_ai Apr 30 '19 at 12:26

0 Answers0