src/sage/sat/solvers/cryptominisat.py: Use lazy_import with feature instead of try/except

Author: Matthias Koeppe

src/sage/sat/solvers/cryptominisat.py

@@ -27,6 +27,10 @@
 
 from .satsolver import SatSolver
 
+from sage.misc.lazy_import import lazy_import
+from sage.features import PythonModule
+lazy_import('pycryptosat', ['Solver'],
+            feature=PythonModule('pycryptosat', spkg='cryptominisat'))
 
 class CryptoMiniSat(SatSolver):
     r"""
@@ -65,11 +69,6 @@ def __init__(self, verbosity=0, confl_limit=None, threads=None):
         if confl_limit is None:
             from sys import maxsize
             confl_limit = maxsize
-        try:
-            from pycryptosat import Solver
-        except ImportError:
-            from sage.misc.package import PackageNotFoundError
-            raise PackageNotFoundError("cryptominisat")
         self._solver = Solver(verbose=int(verbosity), confl_limit=int(confl_limit), threads=int(threads))
         self._nvars = 0
         self._clauses = []