Unified CPU/GPU Dependency

⚡ UV

Optional CPU & GPU

This configuration exposes both cpu and gpu as optional extras.

TOML

pyproject.toml

[project]
name = "test-toml"
version = "0.1.0"
requires-python = ">=3.12,<3.13"
dependencies = []

[project.optional-dependencies]
cpu = [
  "torch",
]
gpu = [
  "torch",
]

[tool.uv]
conflicts = [
    [ 
      { extra = "cpu" }, 
      { extra = "gpu" } 
    ]
]

[tool.uv.sources]
torch = [
  { index = "torch-cpu", extra = "cpu" },
  { index = "torch-gpu", extra = "gpu" },
]

[[tool.uv.index]]
name = "torch-cpu"
url = "https://download.pytorch.org/whl/cpu"

[[tool.uv.index]]
name = "torch-gpu"
url = "https://download.pytorch.org/whl/cu126"

Command

Install without either extra:

uv sync

Install the CPU version:

uv sync --extra cpu

Install the GPU version:

uv sync --extra gpu

You can also use uv pip:

uv pip install -r pyproject.toml

uv pip install -r pyproject.toml --extra cpu

uv pip install -r pyproject.toml --extra gpu

If the installation does not select the expected package from the configured index, try:

uv pip install -r pyproject.toml --extra gpu --index-strategy unsafe-best-match

📦 Poetry

Optional CPU & GPU

This configuration exposes both cpu and gpu as optional extras.

TOML

pyproject.toml

[project]
name = "test-toml"
version = "0.1.0"
requires-python = ">=3.11"
dependencies = []

[project.optional-dependencies]
cpu = [
    "torch (==2.2.0+cpu)",
]
gpu = [
    "torch (==2.5.1+cu121)",
]

[tool.poetry.dependencies]
torch = [
    { markers = "extra != 'gpu' and extra == 'cpu'", source = "torch-cpu" },
    { markers = "extra == 'gpu' and extra != 'cpu'", source = "torch-gpu" },
]

[[tool.poetry.source]]
name = "torch-cpu"
url = "https://download.pytorch.org/whl/cpu"
priority = "explicit"
[[tool.poetry.source]]
name = "torch-gpu"
url = "https://download.pytorch.org/whl/cu121"
priority = "explicit"


[tool.poetry]
package-mode = false
[build-system]
requires = ["poetry-core>=2.0.0,<3.0.0"]
build-backend = "poetry.core.masonry.api"

Command

Install without either extra:

poetry install

Install the CPU version:

poetry install --extras cpu

Install the GPU version:

poetry install --extras gpu

The mutually exclusive markers are:

markers = "extra != 'gpu' and extra == 'cpu'"

for CPU, and:

markers = "extra == 'gpu' and extra != 'cpu'"

for GPU.

This ensures that selecting cpu activates only the CPU dependency, while selecting gpu activates only the GPU dependency.

Default CPU, Optional GPU

This configuration installs the CPU version of PyTorch by default. The GPU version can be selected using the gpu extra.

TOML

pyproject.toml

[project]
name = "test-toml"
version = "0.1.0"
requires-python = ">=3.11"
dependencies = [
    "torch (==2.2.0+cpu) ; extra != 'gpu'",
]

[project.optional-dependencies]
gpu = [
    "torch (==2.5.1+cu121)",
]

[tool.poetry.dependencies]
torch = [
    { markers = "extra != 'gpu'", source = "torch-cpu" },
    { markers = "extra == 'gpu'", source = "torch-gpu" },
]

[[tool.poetry.source]]
name = "torch-cpu"
url = "https://download.pytorch.org/whl/cpu"
priority = "explicit"
[[tool.poetry.source]]
name = "torch-gpu"
url = "https://download.pytorch.org/whl/cu121"
priority = "explicit"


[tool.poetry]
package-mode = false
[build-system]
requires = ["poetry-core>=2.0.0,<3.0.0"]
build-backend = "poetry.core.masonry.api"

Command

Poetry needs re-resolution disabled for this setup:

poetry config installer.re-resolve false

Install the default CPU configuration:

poetry install

Install the GPU configuration:

poetry install --extras gpu

The important part is the marker:

markers = "extra != 'gpu'"

When the gpu extra is not selected, the CPU dependency is selected. When gpu is selected, the GPU dependency is selected instead.