Requirements for python-ext-wasmer

python-ext-wasmer-1_0.md

Ideas for python-ext-wasmer

Guideines to adoption/contribution

• Read the Instance.rs documentation to understand how WASM binaries are ported to Python modules via pyo3 Rust crate.
• Simply put the workflow looks something like:

1. Developer defines Rust functions and compile them via wasm32-unknown-unknown target
2. WASM binary (.wasm) is placed in a Python project
3. With the tools imported via pip install wasmer, developer can load the WASM binary and use the exported functions. This way Rust-defined functions can be called transparently from Python. Great Wasmer!

Ideas for a stable interface

Definitions for snippets below:

• in the context of Python snippets: module is the Python module and function is the exported function (exported functions are the ones defined in a Rust library somewhere and compiled to WASM biaries)
• in the context of pyo3 snippets: a Python module is a type PyModule. It can be declared in different ways

[VERSION 1]

• 1. (hide wasmer internals) Pythonic imports:

from module import function

# `module` should be wasmer Instance and `function`
# should be the exported function

[ADDITION]

• 2. (as per 1. plus improve wasmer PyModule) Implement PyObjectProtocol for

#[pymodule]
fn wasmer(_py: Python, module: &PyModule) -> PyResult<()> { ... }

In alternative to 1. the main module can be used as entrypoint for the functions so, for example:

from wasmer import function

This may be achieved by changing the current definition from:

/// src/lib.rs
#[pymodule]
fn wasmer(_py: Python, module: &PyModule) -> PyResult<()> { ... }

to using #[pymodinit] as here so to take advantage of add_function and the new pyo3::wrap_pyfunction and pyo3::wrap_pymodule

[ADDITION]

• 3. (abstract away loading binary) Autodiscover functionality for binary. User should not be asked to explicitly point and load the .wasm file; on the contrary python-ext-wasmer should look and find the file in project's sub-directories or in a dedicated directory.

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P.S. For now the format of the list can be:

• (objective) Implementation

Ideally should be the exported functions, but this leads a problem with exported memory. Two options here: export it with the exported functions ONLY if there's no other exported memory() function, or left it as an advanced use case that would require direct access to Wasmer API (I think there should no be problems since it's the same memory region, no matter how do you access or reference to it...).

I will keep that in mind thanks. As first step I will try to change as few as possible, basically reusing Instance to be a pyo3.PyModule, with the very same approach to namespace-memory binding.