Migrate from cbcbox to mipster for the bundled CBC library#424
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cbcbox shipped CBC source builds; mipster (https://pypi.org/project/mipster/) ships self-contained, hardware-tuned wheels for Linux x86_64/aarch64, macOS x86_64/arm64, and Windows x86_64 with CPUID auto-dispatch (generic / AVX2 / Haswell / NEON variants). - Replace `cbcbox>=2.929` with `mipster>=0.2.0`. - Use `mipster.lib_path()` instead of platform-specific path joining; this returns the right shared library for the current OS and selected variant. - Drop the manual libCbc.so / libCbc-0.dll / libCbc.dylib branching. - Keep `os.add_dll_directory()` on Windows so the loader can find the sibling MinGW runtime DLLs that mipster bundles next to libmipster-N.dll. - Remove unused Cbc_get/setAllowablePercentageGap CFFI declarations (these are not exported by libmipster and were never called).
Version 0.2.4 fixes three C API bugs required for correctness: - Auto-generate column names so translate() works in lazy callbacks - Sync bound==value when proven optimal (prevents spurious assertion failures) - Restore rSlk/rActv pointers after MIP solve (prevents null-pointer crash) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
highspy's _core.pyd on Windows only exports the Python init symbol (PyInit__core) -- the C API functions like Highs_create are compiled in but not exported as DLL symbols. On Linux/macOS all symbols in a shared library are visible, so ffi.dlopen() works there. After loading the library via ffi.dlopen(), test whether Highs_create is actually accessible. If not (Windows + highspy), set has_highs=False so that all HiGHS tests are skipped gracefully instead of crashing with 'function/symbol not found' errors. Users on Windows who need HiGHS can install highsbox (which ships a proper highs.dll with exported C symbols) and set PMIP_HIGHS_LIBRARY to point to it. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
highspy's _core.pyd on Windows does not export C symbols (only PyInit_*
is exported from a Windows DLL by default). On Linux/macOS the .so
exports all symbols so ffi.dlopen + Highs_create works fine; on Windows
it raises AttributeError.
Changes:
- After dlopen succeeds, probe Highs_create accessibility. If it fails
(Windows + highspy), automatically retry with highsbox's highs.dll.
- highsbox is added as a Windows-only optional dependency in [highs]:
highsbox>=1.9.0; sys_platform == 'win32'
so 'pip install mip[highs]' on Windows installs both highspy (Python
bindings) and highsbox (C API DLL), giving full HiGHS functionality.
- Hoist the highsbox path resolver to a module-level helper function
_get_highsbox_libfile() so it is reachable both at initial load and
at the fallback probe point.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
On PyPy, the GC may call __del__ on an object whose __init__ raised before all attributes were set (e.g. SolverGurobi.__init__ raises early when Gurobi is not installed, before _ownsModel/_venv_loaded are set). CPython avoids this because reference-counting drops the object immediately; PyPy's tracing GC processes it later. Replace bare attribute access in __del__ with getattr(..., default) in: - SolverGurobi.__del__: guard _ownsModel and _venv_loaded - SolverHighs.__del__: guard _model (avoid calling Highs_destroy(NULL)) - SolverCbc.__del__: guard _model (avoid calling Cbc_deleteModel(NULL)) - SolverOsi.__del__: guard owns_solver Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Summary
Replaces the
cbcboxbuild-time dependency withmipster, which ships self-contained, hardware-tuned binary wheels for all major platforms.All third-party runtime libraries travel inside the wheel — no system dependencies.
Changes
pyproject.toml:cbcbox>=2.929→mipster>=0.2.0mip/cbc.py:mipster.lib_path()instead of platform-specific path joining; this returns the right shared library for the current OS and selected variant.libCbc.so/libCbc-0.dll/libCbc.dylibbranching.os.add_dll_directory()on Windows so the loader can find sibling MinGW runtime DLLs.Cbc_get/setAllowablePercentageGapCFFI declarations (not exported bylibmipster, never called).Net diff: 41 lines removed, 11 added in
cbc.py.Test plan
pip install .pullsmipster 0.2.xandcffi; nocbcbox.os.add_dll_directory()for sibling MinGW runtime libs.Compatibility
mipsterbinary-compatible withlibCbcfrom upstream Cbc; the C ABI used by python-mip is unchanged.mipster>=0.2.0is the floor because that's the first release shippinglib_path()and the bundled runtime libraries.🤖 Generated with Claude Code