System.Memory Polyfill for .NET Framework 4.0

Provides types for efficient representation and pooling of managed, stack, and native memory segments and sequences of such segments, along with primitives to parse and format UTF-8 encoded text stored in those memory segments.

Commonly Used Types:

• System.Span
• System.ReadOnlySpan
• System.Memory
• System.ReadOnlyMemory
• System.Buffers.MemoryPool
• System.Buffers.ReadOnlySequence
• System.Buffers.Text.Utf8Parser
• System.Buffers.Text.Utf8Formatter

This package adds support for System.Memory types on .NET Framework 4.0.

As the source code is not available for the System.Memory package that works on .NET Framework 4.5, types in this package have either been decompiled from System.Memory 4.5.5 or have been sourced from newer versions of .NET. Most of the tests from the last release of .NET Core 3.1 (version 3.1.29) have been ported and are all passing. There are 103 tests that pass on this library that don't pass on System.Memory, so it contains some behavior that is more in line with later versions of .NET than with System.Memory 4.5.5. But these are minor (forward-compatible) differences that most users won't notice.

This is not meant to be an upgrade to System.Memory 4.5.5, it is simply to add support on the net40 target for all of the existing APIs in System.Memory 4.5.5. It is recommended to use the official release of System.Memory on newer versions of .NET.

Interop with System.Memory on Targets > net40

Since the runtime for net40 hasn't been supported for many years, most likely you will be using a newer runtime with this library. But you may be interoperating with other components that target System.Runtime.CompilerServices.Unsafe, which will cause type collisions by default.

In this case, it is recommended to remove System.Memory and its dependencies from compilation and add System.Memory in its place. Add the following to your .csproj or .vbproj file. This example is for using net452.

  <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">
    <!-- ExcludeAssets=compile removes the dependency from being referenced.
         ExcludeAssets=runtime removes the dependency from the build output. -->
    <PackageReference Include="System.Buffers"
                      Version="4.5.1"
                      ExcludeAssets="compile;runtime" />
    <PackageReference Include="System.Memory"
                      Version="4.5.5"
                      ExcludeAssets="compile;runtime" />
    <PackageReference Include="System.Runtime.CompilerServices.Unsafe"
                      Version="6.0.0"
                      ExcludeAssets="compile;runtime" />
    <PackageReference Include="NetFx.System.Memory"
                      Version="4.0.0" />
  </ItemGroup>

NOTE: Only SDK-style projects are supported using this method.

For transitive dependencies (that is, dependencies that are not directly referenced) that have a net40 target, consider forcing a specific target framework.

Saying Thanks

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