Merge pull request #487 from isuruf/subs-except

Mark subs as throwing exceptions

Author: bjodah

symengine/lib/symengine.pxd

@@ -168,9 +168,9 @@ cdef extern from "<symengine/basic.h>" namespace "SymEngine":
     void cse(vec_pair &replacements, vec_basic &reduced_exprs, const vec_basic &exprs) except+ nogil
 
 cdef extern from "<symengine/subs.h>" namespace "SymEngine":
-    rcp_const_basic msubs (rcp_const_basic &x, const map_basic_basic &x) nogil
-    rcp_const_basic ssubs (rcp_const_basic &x, const map_basic_basic &x) nogil
-    rcp_const_basic xreplace (rcp_const_basic &x, const map_basic_basic &x) nogil
+    rcp_const_basic msubs (rcp_const_basic &x, const map_basic_basic &x) except+ nogil
+    rcp_const_basic ssubs (rcp_const_basic &x, const map_basic_basic &x) except+ nogil
+    rcp_const_basic xreplace (rcp_const_basic &x, const map_basic_basic &x) except+ nogil
 
 cdef extern from "<symengine/derivative.h>" namespace "SymEngine":
     rcp_const_basic diff "SymEngine::sdiff"(rcp_const_basic &arg, rcp_const_basic &x) except+ nogil

symengine/tests/test_subs.py

@@ -1,7 +1,7 @@
 import unittest
 
 from symengine.test_utilities import raises
-from symengine import Symbol, sin, cos, sqrt, Add, function_symbol, have_numpy
+from symengine import Symbol, sin, cos, sqrt, Add, function_symbol, have_numpy, log
 
 
 def test_basic():
@@ -24,6 +24,12 @@ def test_sin():
     assert e.subs(x, 0) == 1
 
 
+def test_subs_exception():
+    x = Symbol("x")
+    expr = sin(log(x))
+    raises(RuntimeError, lambda: expr.subs({x: 0}))
+
+
 def test_args():
     x = Symbol("x")
     e = cos(x)