---
title: fileID()
framework: swift
role: symbol
role_heading: Macro
path: swift/fileid()
---

# fileID()

Produces a unique identifier for the source file in which the macro appears.

## Declaration

```swift
@freestanding(expression) macro fileID<T>() -> T where T : ExpressibleByStringLiteral
```

## Overview

Overview The unique identifier has the form module/file, where file is the name of the file in which the expression appears and module is the name of the module that this file is part of. Because #fileID doesn’t embed the full path to the source file, unlike #filePath, it gives you better privacy and reduces the size of the compiled binary. Note: To parse a #fileID expression, read the module name as the text before the first slash (/) and the filename as the text after the last slash. In future versions of Swift, the string might contain multiple slashes, such as MyModule/some/disambiguation/MyFile.swift. This macro’s value can be changed by #sourceLocation, as described in Line Control Statement in The Swift Programming Language.

## See Also

### Getting Source Location Information

- [file()](swift/file().md)
- [filePath()](swift/filepath().md)
- [function()](swift/function().md)
- [line()](swift/line().md)
- [column()](swift/column().md)