[API Proposal]: Add Length and IsEmpty properties to System.BinaryData

[0xced]

Background and motivation

Getting the length of a System.BinaryData instance is something quite natural. Currently, the best way to get the length is by doing data.ToMemory().Length which is not very pleasant.

There's also a trap where one could do data.ToArray().Length or even data.ToStream().Length and this would allocate!

Having a Length property solves both issues: code is more readable and ensures no allocation.

An IsEmpty property would also be welcome.

API Proposal

namespace System;

public class BinaryData
{
    public int Length { get; }
    public bool IsEmpty { get; }
}

API Usage

void ProcessData(BinaryData data, string outputFile)
{
    if (data.IsEmpty)
    {
        Console.WriteLine($"No data available to write to {outputFile}");
    }
    else
    {
        Console.WriteLine($"Writing {data.Length} bytes to {outputFile}");
        // ... actual implementation ...
    }
}

Alternative Designs

No response

Risks

There are no risks associated with this proposition. The implementations of those properties are trivial and would just call respectively _bytes.Length and _bytes.IsEmpty.

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[ghost]

Tagging subscribers to this area: @dotnet/area-system-memory
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Background and motivation

Getting the length of a System.BinaryData instance is something quite natural. Currently, the best way to get the length is by doing data.ToMemory().Length which is not very pleasant.

There's also a trap where one could do data.ToArray().Length or even data.ToStream().Length and this would allocate!

Having a Length property solves both issues: code is more readable and ensures no allocation.

An IsEmpty property would also be welcome.

API Proposal

namespace System;

public class BinaryData
{
    public int Length { get; }
    public bool IsEmpty { get; }
}

API Usage

void ProcessData(BinaryData data, string outputFile)
{
    if (data.IsEmpty)
    {
        Console.WriteLine($"No data available to write to {outputFile}");
    }
    else
    {
        Console.WriteLine($"Writing {data.Length} bytes to {outputFile}");
        // ... actual implementation ...
    }
}

Alternative Designs

No response

Risks

There are no risks associated with this proposition. The implementations of those properties are trivial and would just call respectively _bytes.Length and _bytes.IsEmpty.

Author:	0xced
Assignees:	-
Labels:	api-suggestion, area-System.Memory, untriaged
Milestone:	-

[0xced]

Is there anything I should add to the proposal to initiate a discussion? Some months later I have worked with BinaryData again and struggled with this exact same issue again.

Ping @jeffhandley

[adamsitnik]

Is there anything I should add to the proposal to initiate a discussion? S

Apologies for the delay. The proposal looks good to me, I've marked it as ready for review. Looking at https://apireview.net/backlog I estimate that it should get reviewed within next two weeks.

@0xced thank you!

[bartonjs]

Video

Looks good as proposed.

We briefly discussed Length vs Count, and feel that Length is more appropriate here because it's representing a fixed size window of data, like Span/Memory/Array, vs a point-in-time number like List and the other collections.

namespace System;

public class BinaryData
{
    public int Length { get; }
    public bool IsEmpty { get; }
}

[0xced]

A pull request addressing this issue is ready: #86721