peridem_env.py

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# -------------------------------------------
# Copyright (c) 2021 - 2026 Prashant K. Jha
# -------------------------------------------
# PeriDEM https://github.com/prashjha/PeriDEM
#
# Distributed under the Boost Software License, Version 1.0. (See accompanying
# file LICENSE)
 
"""Make ``import peridem`` work from a build tree.
 
Examples import this first so they run straight from a checkout without
``pip install``. If peridem is already importable (installed, or PYTHONPATH is
set) this does nothing.
"""
 
from __future__ import annotations
 
import sys
from pathlib import Path
 
__all__ = ["REPO_ROOT", "ensure_peridem"]
 
REPO_ROOT = next(
    p for p in Path(__file__).resolve().parents
    if (p / "python" / "peridem" / "__init__.py").is_file()
)
 
_BUILD_DIRS = ("build/linux/python", "build/python", "build/Release/python",
               "build/Debug/python")
 
 
def ensure_peridem() -> None:
    try:
        import peridem  # noqa: F401
 
        return
    except ImportError:
        pass
    # The staged package under build/ carries the compiled _core; the source
    # python/ directory does not, so it must never shadow it.
    for rel in _BUILD_DIRS:
        cand = REPO_ROOT / rel
        if (cand / "peridem" / "__init__.py").is_file():
            sys.path.insert(0, str(cand))
            break
    else:
        sys.path.insert(0, str(REPO_ROOT / "python"))
    try:
        import peridem  # noqa: F401
    except ImportError as exc:  # pragma: no cover - build guidance
        raise SystemExit(
            "cannot import peridem. Build the extension first:\n"
            f"  cmake -S {REPO_ROOT} -B {REPO_ROOT}/build -DEnable_Python=ON\n"
            f"  cmake --build {REPO_ROOT}/build --target peridem_core PeriDEM -j\n"
            f"({exc})"
        ) from exc
 
 
ensure_peridem()