Centralize sparsediffpy import into _bindings.py (#174)

* Centralize sparsediffpy import into _bindings.py

Move the duplicated try/except import of sparsediffpy from c_problem.py
and converters.py into a single _bindings.py module.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* cleanup fix

* fix import issue

* fix import for c_problem as well

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: Transurgeon

cvxpy/reductions/solvers/nlp_solvers/diff_engine/c_problem.py

@@ -16,17 +16,9 @@
 """
 
 import numpy as np
+from sparsediffpy import _sparsediffengine as _diffengine
 
 import cvxpy as cp
-
-# Import the low-level C bindings
-try:
-    from sparsediffpy import _sparsediffengine as _diffengine
-except ImportError as e:
-    raise ImportError(
-        "NLP support requires sparsediffpy. Install with: pip install sparsediffpy"
-    ) from e
-
 from cvxpy.reductions.solvers.nlp_solvers.diff_engine.converters import (
     build_variable_dict,
     convert_expr,

cvxpy/reductions/solvers/nlp_solvers/diff_engine/converters.py

@@ -21,18 +21,11 @@
 
 import numpy as np
 from scipy import sparse
+from sparsediffpy import _sparsediffengine as _diffengine
 
 import cvxpy as cp
 from cvxpy.reductions.inverse_data import InverseData
 
-# Import the low-level C bindings
-try:
-    from sparsediffpy import _sparsediffengine as _diffengine
-except ImportError as e:
-    raise ImportError(
-        "NLP support requires sparsediffpy. Install with: pip install sparsediffpy"
-    ) from e
-
 
 def normalize_shape(shape):
     """Normalize shape to 2D (d1, d2) for the C engine."""