File System

Atom provides IAtomFileSystem — a build-aware file system abstraction that layers path resolution on top of System.IO.Abstractions.IFileSystem.

`IAtomFileSystem`

Available via IBuildAccessor.AtomFileSystem, this interface gives you:

All standard IFileSystem operations (read, write, delete, etc.)
Path resolution via GetPath(key) — looks up well-known paths by key
A CurrentDirectory property returning a RootedPath

Resolving Well-Known Paths

var root = AtomFileSystem.GetPath("Root");
var artifacts = AtomFileSystem.GetPath("Artifacts");
var publish = AtomFileSystem.GetPath("Publish");

Paths are resolved by querying registered IPathProvider implementations in priority order and are cached after first resolution.

`RootedPath`

RootedPath is a value type that wraps an absolute directory/file path and is bound to an IAtomFileSystem instance. It supports the / operator for path combination:

var projectDir = AtomFileSystem.GetPath("Root") / "src" / "MyProject";
var csproj = projectDir / "MyProject.csproj";

Because a RootedPath carries a reference to the file system, you can perform I/O directly:

var content = AtomFileSystem.File.ReadAllText(csproj);

`IPathProvider`

Implement IPathProvider to register custom well-known paths:

public interface IPathProvider
{
    RootedPath? GetPath(string key);
}

Return null if your provider doesn't handle the requested key — the next provider in the chain will be tried.

Built-in Path Keys

Key	Description
`Root`	Repository / solution root
`Artifacts`	Build artifacts directory
`Publish`	Publish output directory

`IPathMarker`

For statically determined paths (e.g. source-generated project paths), implement IPathMarker:

public interface IPathMarker
{
    static abstract RootedPath Path(IAtomFileSystem fileSystem);
}

Resolve with AtomFileSystem.GetPath<MyPathMarker>().

Next Steps

→ Process Runner

Table of Contents

File System

IAtomFileSystem