fn new()

in bindings/python/src/lib.rs [434:536]
83 lines of code
9 McCabe index (conditional complexity)

    fn new(filename: PathBuf, framework: Framework, device: Option<Device>) -> PyResult<Self> {
        let file = File::open(&filename).map_err(|_| {
            PyFileNotFoundError::new_err(format!(
                "No such file or directory: {}",
                filename.display()
            ))
        })?;
        let device = device.unwrap_or(Device::Cpu);

        if device != Device::Cpu && framework != Framework::Pytorch {
            return Err(SafetensorError::new_err(format!(
                "Device {device} is not supported for framework {framework}",
            )));
        }

        // SAFETY: Mmap is used to prevent allocating in Rust
        // before making a copy within Python.
        let buffer = unsafe { MmapOptions::new().map_copy_read_only(&file)? };

        let (n, metadata) = SafeTensors::read_metadata(&buffer).map_err(|e| {
            SafetensorError::new_err(format!("Error while deserializing header: {e}"))
        })?;

        let offset = n + 8;

        Python::with_gil(|py| -> PyResult<()> {
            match framework {
                Framework::Pytorch => {
                    let module = PyModule::import(py, intern!(py, "torch"))?;
                    TORCH_MODULE.get_or_init_py_attached(py, || module.into())
                }
                _ => {
                    let module = PyModule::import(py, intern!(py, "numpy"))?;
                    NUMPY_MODULE.get_or_init_py_attached(py, || module.into())
                }
            };

            Ok(())
        })?;

        let storage = match &framework {
            Framework::Pytorch => Python::with_gil(|py| -> PyResult<Storage> {
                let module = get_module(py, &TORCH_MODULE)?;

                let version: String = module.getattr(intern!(py, "__version__"))?.extract()?;
                let version = Version::from_string(&version).map_err(SafetensorError::new_err)?;

                // Untyped storage only exists for versions over 1.11.0
                // Same for torch.asarray which is necessary for zero-copy tensor
                if version >= Version::new(1, 11, 0) {
                    // storage = torch.ByteStorage.from_file(filename, shared=False, size=size).untyped()
                    let py_filename: PyObject = filename
                        .to_str()
                        .ok_or_else(|| {
                            SafetensorError::new_err(format!(
                                "Path {} is not valid UTF-8",
                                filename.display()
                            ))
                        })?
                        .into_pyobject(py)?
                        .into();
                    let size: PyObject = buffer.len().into_pyobject(py)?.into();
                    let shared: PyObject = PyBool::new(py, false).to_owned().into();
                    let (size_name, storage_name) = if version >= Version::new(2, 0, 0) {
                        (intern!(py, "nbytes"), intern!(py, "UntypedStorage"))
                    } else {
                        (intern!(py, "size"), intern!(py, "ByteStorage"))
                    };

                    let kwargs =
                        [(intern!(py, "shared"), shared), (size_name, size)].into_py_dict(py)?;
                    let storage = module
                        .getattr(storage_name)?
                        // .getattr(intern!(py, "from_file"))?
                        .call_method("from_file", (py_filename,), Some(&kwargs))?;

                    let untyped: PyBound<'_, PyAny> = match storage.getattr(intern!(py, "untyped"))
                    {
                        Ok(untyped) => untyped,
                        Err(_) => storage.getattr(intern!(py, "_untyped"))?,
                    };
                    let storage = untyped.call0()?.into_pyobject(py)?.into();
                    let gil_storage = OnceLock::new();
                    gil_storage.get_or_init_py_attached(py, || storage);

                    Ok(Storage::TorchStorage(gil_storage))
                } else {
                    Ok(Storage::Mmap(buffer))
                }
            })?,
            _ => Storage::Mmap(buffer),
        };

        let storage = Arc::new(storage);

        Ok(Self {
            metadata,
            offset,
            framework,
            device,
            storage,
        })
    }