[Arrays]

[dlangBugzillaToGithub]

Kurt Krueckeberg reported this on 2021-12-09T14:14:25Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=22580

CC List

• Andrej Mitrovic (@AndrejMitrovic)

Description

I am new to D, but the code example explanation in section 12.6 is confusing. The code example in section 12.6 refers to the "slice operator":

"When the slice operator appears as the left-hand side of an assignment expression, it means that the contents of the array are the target of the assignment rather than a reference to the array..."

Is there really a special "slice operator"? The operator used in the example in section 12.6 is array index operator, [].  So shouldn't the explanation be changed to refer to the index operator (being applied to a slice that appears on the left-hand side of an assignment statement)? To me, it is clearer to say something like:

"When the slice appears on the left-hand side of an assignment with the index operator, it means that the contents of the array are the target of the assignment rather than a reference to the array..."

Or to say:

"When the slice is indexed with the [] operator and it appears on the left-hand side of an assignment, it means that the contents of the array are the target of the assignment rather than a reference to the array..."

Or simply:

"When the slice is indexed and it appears on the left-hand side of an assignment, it means that the contents of the array are the target of the assignment rather than a reference to the array..."

[dlangBugzillaToGithub]

andrej.mitrovich (@AndrejMitrovic) commented on 2022-07-06T07:55:39Z

(In reply to Kurt Krueckeberg from comment #0)
> I am new to D, but the code example explanation in section 12.6 is
> confusing. The code example in section 12.6 refers to the "slice operator":
> 
> "When the slice operator appears as the left-hand side of an assignment
> expression, it means that the contents of the array are the target of the
> assignment rather than a reference to the array..."
> 
> Is there really a special "slice operator"? The operator used in the example
> in section 12.6 is array index operator, [].  So shouldn't the explanation
> be changed to refer to the index operator (being applied to a slice that
> appears on the left-hand side of an assignment statement)? To me, it is
> clearer to say something like:
> 
> "When the slice appears on the left-hand side of an assignment with the
> index operator, it means that the contents of the array are the target of
> the assignment rather than a reference to the array..."
> 
> Or to say:
> 
> "When the slice is indexed with the [] operator and it appears on the
> left-hand side of an assignment, it means that the contents of the array are
> the target of the assignment rather than a reference to the array..."
> 
> Or simply:
> 
> "When the slice is indexed and it appears on the left-hand side of an
> assignment, it means that the contents of the array are the target of the
> assignment rather than a reference to the array..."

The slice operator is specifically `[]` or `[1..2]`. And you can think of `[]` as being the same as `[0..$]`, where $ is the array length.

The index operator is `[1]` for example. It doesn't return a slice of the original array, it returns a single element from the array. That's indexing, not slicing.

Perhaps there should be better documentation about the difference between the two though.