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Renaming

UniFFI provides two ways to customize names in generated bindings:

  1. Proc-macro attributes - Use variants of #[uniffi(name = "...")] to rename items directly in Rust code. See proc-macro renaming.
  2. TOML configuration - Define language-specific renames in uniffi.toml.

TOML-based Renaming

You can rename types, functions, methods, constructors, and their members (fields, variants, arguments) on a per-language basis using uniffi.toml. The intended use-case here is for when a name could be made more idiomatic in one specific binding - you can rename many things unconditionally for all bindings using proc macros.

An example uniffi.toml which is renaming Python: 

[bindings.python.rename]
# Rename types
# `struct MyRecord { .. }` -> `PythonRecord`
MyRecord = "PythonRecord"

# Rename nested items using dot notation
# `struct MyRecord { field: u32  }` -> `PythonRecord(python_field ...)`
"MyRecord.field" = "python_field"
"MyEnum.VariantA" = "PythonVariantA"
"MyEnum.VariantA.int_field" = "python_field"

# `fn my_function(first_arg: u8)` -> `def python_function(python_arg)`
"my_function" = "python_function"
"my_function.first_arg" = "python_arg"
"MyObject.method" = "python_method"
"MyObject.method.foo" = "python_foo"

The same pattern applies to all renameable items: records, record fields, enums, enum variants, enum variant fields, objects/callback interfaces/traits, and all "callables" and arguments.

Notes

  • Each crate defines its own rename configuration, you cannot rename types from external crates
  • uniffi normalizes names for each language (eg, my_func becomes myFunc in some languages) after the renaming is applied. For example, renaming my_func to renamed_func would cause the final name to be renamedFunc in those languages.
  • All builtin bindings support this but external bindings may not.
  • Renaming the primary constructor "works", but will have no impact in bindings as the name isn't used.