lazyimports

A backport of Python 3.15's lazy import statement for older Python versions.

On Python 3.15+, you can write:

lazy import numpy
lazy from os.path import join

This package provides the same deferred-import behaviour on every supported Python version (3.6 through 3.15) via a small, focused API.

Why?

Deferring heavy imports until they are actually needed can noticeably speed up module load times and reduce memory usage — useful for CLIs, plugins, and any code path that imports optional dependencies.

Installation

pip install python-lazyimports

Usage

Lazy import

from lazyimports import lazy_import

np = lazy_import("numpy")          # not imported yet
pd = lazy_import("pandas")         # not imported yet

# ``numpy`` is loaded on first attribute access:
arr = np.array([1, 2, 3])

Lazy from X import Y

from lazyimports import lazy_from

join, basename = lazy_from("os.path", "join", "basename")
result = join("a", "b")            # os.path is imported here

Grouping with lazy()

from lazyimports import lazy, lazy_import

with lazy():
    np = lazy_import("numpy")
    pd = lazy_import("pandas")
    tf = lazy_import("tensorflow")
# None of the modules are imported until first use.

Inspecting and forcing load

from lazyimports import is_lazy, force_load

proxy = lazy_import("json")
assert is_lazy(proxy)
assert not is_lazy(json)           # False for already-imported modules

real = force_load(proxy)           # resolve now and return the real module

API

Symbol	Description
lazy_import(name, package=None)	Return a lazy proxy for module name.
lazy_from(module, *names)	Lazily import specific names from a module.
is_lazy(obj)	Return True if obj is a LazyModule.
force_load(obj)	Force resolution of a LazyModule; pass-through for anything else.
lazy()	Context manager for grouping lazy imports (no-op marker).
LazyModule	The proxy class returned by lazy_import().
NATIVE_LAZY_IMPORT	True when running on Python 3.15+.
SUPPORT_LAZY_IMPORT	True on every version (this package provides its own implementation).

Python 3.15+ native syntax

When you are running on Python 3.15+, you may prefer the native syntax. The package's own API still works identically, so you can use either:

# Native (Python 3.15+ only):
lazy import numpy

# Cross-version equivalent via this package:
from lazyimports import lazy_import
numpy = lazy_import("numpy")

Compatibility

• Python 3.6 through 3.15
• No third-party dependencies — uses only the standard library (contextlib, importlib, sys, types)

Running the tests

python -m unittest test_lazyimports -v

Retired

This project will reach its end-of-life around October 1, 2031 — the official EOL date of Python 3.15 — and the exact timeline could be slightly delayed. We plan to ship the final stable release in November 2031. After this release, all support will cease and the repository will be officially archived, as this library is developed solely to bring lazy import compatibility to Python 3.15 and older versions.

License

MIT