Using FileManager in Manifest

[Ernest0-Production]

What problem or need do you have?

Hi! Is it bad form or dangerous to use a FileManager in a Project.swift manifest, for example to check that a some file or folder exists in a specific directory or to perform other side effects (create file)?

Will caching the manifest prevent the manifest from running again?

Potential solution

No response

macOS version

13.6.3

Tuist version

4.6.0

Xcode version

15.2

[fortmarek]

Hey!

Doing side effects and reading the file system is not recommended to do in your manifests. We cache the JSON manifest representation, so we don't have to compile them on every generate, so doing side effects in them will lead to indeterministic tuist generate invocations.

You can use environment variables to pass in state and then read that state in your manifest file.

[Ernest0-Production]

Thanks for the tip!

Could you please explain how the environment variables affects the manifest cache?
Does this mean that the manifest cache is ignored when passing custom TUIST_XYZ variables?

[danieleformichelli]

The value of the variable is part of the cache hash, so if the input (env variable) changes, the cache is invalidated

[Ernest0-Production]

The value of the variable is part of the cache hash, so if the input (env variable) changes, the cache is invalidated

@danieleformichelli Are all environment variables taken into account, or only those with the TUIST prefix?