• Brother Bill (5/5) Aug 30 For the modern D developer, which is the more preferred choice,
• monkyyy (2/7) Aug 30 different things `is` is mostly a special case like `is null`
• Steven Schveighoffer (11/16) Aug 30 `is` will do a direct bitwise comparison of the two sides, and
• IchorDev (9/13) Aug 31 This question doesn't make much sense. It's like if you asked the
• H. S. Teoh (8/10) Aug 31 [...]

Brother Bill <brotherbill mail.com> writes:

For the modern D developer, which is the more preferred choice, 
to use 'is' or '=='?

Do the Style Guidelines or other authorities prefer one to the 
other for modern D coding?

Or is either equally satisfactory?

monkyyy <crazymonkyyy gmail.com> writes:

On Saturday, 30 August 2025 at 22:15:26 UTC, Brother Bill wrote:
 For the modern D developer, which is the more preferred choice, 
 to use 'is' or '=='?

 Do the Style Guidelines or other authorities prefer one to the 
 other for modern D coding?

 Or is either equally satisfactory?


different things `is` is mostly a special case like `is null`

Steven Schveighoffer <schveiguy gmail.com> writes:

On Saturday, 30 August 2025 at 22:15:26 UTC, Brother Bill wrote:
 For the modern D developer, which is the more preferred choice, 
 to use 'is' or '=='?

`is` will do a direct bitwise comparison of the two sides, and 
cannot be hooked with an operator overload. This tests for 
*identity* (are the two sides the same instance).

`==` will use a type-specific comparison controlled by either the 
lhs type or the rhs type. This tests for *logical equality*.

 Do the Style Guidelines or other authorities prefer one to the 
 other for modern D coding?

 Or is either equally satisfactory?

For value types that do not hook logical equality, `is` and `==` 
can be the same operation. There are some exceptions, for example 
floating-point numbers.

`is` is generally preferred for pointer or reference comparisons.

-Steve

IchorDev <zxinsworld gmail.com> writes:

On Saturday, 30 August 2025 at 22:15:26 UTC, Brother Bill wrote:
 Do the Style Guidelines or other authorities prefer one to the 
 other for modern D coding?

No: https://dlang.org/dstyle.html

 For the modern D developer, which is the more preferred choice, 
 to use 'is' or '=='?

This question doesn't make much sense. It's like if you asked the 
same thing about delegates vs functions.
`is` tells you if its operands are exact bit-for-bit matches, 
whereas `==` usually compares the contents of two things and may 
be overloaded using `opCmp` or `opEquals`.
For clarity's sake, `is` should generally be used for pointer 
comparison.

"H. S. Teoh" <hsteoh qfbox.info> writes:

On Sat, Aug 30, 2025 at 10:15:26PM +0000, Brother Bill via Digitalmars-d-learn
wrote:
 For the modern D developer, which is the more preferred choice, to use
 'is' or '=='?

[...]

They have two different meanings.  `is` is for determining identity (is
this the same variable); whereas `==` is for comparing values (do these
two variables have the same value).  They are not interchangeable.


T

-- 
There are 10 kinds of people in the world: those who can count in binary, and
those who can't.