`auto` keyword origins

Jun 26, 2023

Alexander Tretyak

Jun 26, 2023

Adam D Ruppe

Jun 26, 2023

Alexander Tretyak

Jun 26, 2023

Patrick Schluter

On Monday, 26 June 2023 at 00:00:48 UTC, Alexander Tretyak wrote: > I'm just curious when was the `auto` keyword introduced in D? What's New for D 0.137 Oct 24, 2005 New/Changed Features Added implicit type inference. from: https://digitalmars.com/d/1.0/changelog1.html Though the auto keyword was around earlier (it actually comes from old C), and technically doesn't mean exactly what you think it means - the `auto` keyword isn't what's magic, you can use many others in its place (most the time) like `const` and `immutable` among more - but the feature referred to is the type inference. > I always thought that `auto` in D was taken from C++. But what if it is opposite, i.e. C++11's `auto` was inspired by D's `auto`? It probably went both ways. The C++ proposal you linked is definitely earlier than D adopting the thing, and perhaps D's use of it helped prompt the C++ committee to adopt it too.

June 26, 2023

Re: `auto` keyword origins

Posted by Patrick Schluter
in reply to Alexander Tretyak

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Patrick Schluter

Posted in reply to Alexander Tretyak

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On Monday, 26 June 2023 at 00:00:48 UTC, Alexander Tretyak wrote:

I'm just curious when was the auto keyword introduced in D?

The reason I am asking is because D language appeared in 2001, but C++ proposal with auto keyword new semantics dated April 28, 2003.

I always thought that auto in D was taken from C++. But what if it is opposite, i.e. C++11's auto was inspired by D's auto?

auto is a C keyword defining the storage class of a variable. It's placed at the same place as register/const and static.

In D it has the same role (i.e. it's a storage class). The type inference has nothing to do with auto. It is just necessary for the grammar to represent a type of a declaration.

a=1;

if the type is omitted, the parser cannot distinguish between a declaration with initialiser or an assignment. You have to put either a type or a storage class to disambguate

const a=1;
immutabe b=2L;
auto c=5.4;
static d=w"Hello";

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