also test cython<3.0.0

.github/workflows/test.yml

@@ -13,6 +13,7 @@ jobs:
     strategy:
       matrix:
         python-version: ["3.8", "3.9", "3.10", "3.11"]
+        cython: ["cython", "cython<3.0.0"]
     steps:
       - uses: actions/checkout@v2
         with: { submodules: recursive }
@@ -21,7 +22,7 @@ jobs:
       - name: Install pplpy dependencies
         shell: bash -l {0}
         run: |
-          mamba env update --quiet -n test -f environment.yml
+          mamba install --quiet setuptools gmpy2 cysignals ppl "${{matrix.cython}}"
           conda list
       - name: Install pplpy
         shell: bash -l {0}

README.rst

@@ -94,20 +94,12 @@ Requirements
 
 - `PPL <http://bugseng.com/products/ppl/>`_
 
-- `Cython <http://cython.org>`_
+- `Cython <http://cython.org>`_ (tested with both 0.29 and 3.0)
 
 - `cysignals <https://pypi.python.org/pypi/cysignals>`_
 
-- `gmpy2 <https://pypi.python.org/pypi/gmpy2>`_: version >= 2.1.0a4 (see below)
+- `gmpy2 <https://pypi.python.org/pypi/gmpy2>`_
 
-On Debian/Ubuntu systems these can be installed with::
+On Debian/Ubuntu systems the dependencies can be installed with::
 
-    $ sudo apt-get install libgmp-dev libmpfr-dev libmpc-dev libppl-dev cython
-    $ pip install cysignals --user
-    $ pip install gmpy2 --pre --user
-
-The pip optional option `--user` allows to install python packages for a single
-user with no need for administrator rights. The two pip install commands might
-be replaced by `sudo pip install PKG` (not recommended). On recent Debian/Ubuntu systems,
-cysignals is also available as a package under the name `python-cysignals` for
-Python 2 and `python3-cysignals` for Python 3.
+    $ sudo apt-get install libgmp-dev libmpfr-dev libmpc-dev libppl-dev cython3 python3-gmpy2 python3-cysignals-pari

ppl/linear_algebra.pyx

@@ -284,7 +284,11 @@ cdef class Variable(object):
         ...
         TypeError: ppl coefficients must be integral
         """
-        return Linear_Expression(self) * other
+        if isinstance(self, Variable):
+            return Linear_Expression(self) * other
+        else:
+            # NOTE: this code path will only be executed when compiled with cython < 3.0.0
+            return Linear_Expression(other) * self
 
     def __rmul__(self, other):
         return Linear_Expression(self) * other
@@ -641,11 +645,12 @@ cdef class Linear_Expression(object):
             a = args[0]
             b = args[1]
             self.thisptr = new PPL_Linear_Expression()
-            if isinstance(a, dict) and a:
-                self.thisptr.set_space_dimension(1 + max(a))
-                for i, coeff in a.items():
-                    self.thisptr.set_coefficient(PPL_Variable(i), PPL_Coefficient_from_pyobject(coeff))
-            elif a:
+            if isinstance(a, dict):
+                if a:
+                    self.thisptr.set_space_dimension(1 + max(a))
+                    for i, coeff in a.items():
+                        self.thisptr.set_coefficient(PPL_Variable(i), PPL_Coefficient_from_pyobject(coeff))
+            else:
                 self.thisptr.set_space_dimension(len(a))
                 for i, coeff in enumerate(a):
                     self.thisptr.set_coefficient(PPL_Variable(i), PPL_Coefficient_from_pyobject(coeff))
@@ -1088,7 +1093,11 @@ cdef class Linear_Expression(object):
         """
         cdef Linear_Expression lhs, rhs
 
-        lhs = <Linear_Expression> self
+        if isinstance(self, Linear_Expression):
+            lhs = <Linear_Expression> self
+        else:
+            # NOTE: this code path will only be executed when compiled with cython < 3.0.0
+            lhs = Linear_Expression(self)
 
         if isinstance(other, Linear_Expression):
             rhs = <Linear_Expression> other
@@ -1181,9 +1190,9 @@ cdef class Linear_Expression(object):
         >>> from ppl import Variable
         >>> x = Variable(0)
         >>> y = Variable(1)
-        >>> 8*(x+1)
+        >>> 8 * (x + 1)
         8*x0+8
-        >>> y*8
+        >>> y * 8
         8*x1
         >>> 2**128 * x
         340282366920938463463374607431768211456*x0
@@ -1194,8 +1203,14 @@ cdef class Linear_Expression(object):
         """
         cdef Linear_Expression e
         cdef c
-        e = <Linear_Expression> self
-        c = other
+
+        if isinstance(self, Linear_Expression):
+            e = <Linear_Expression> self
+            c = other
+        else:
+            # NOTE: this code path will only be executed when compiled with cython < 3.0.0
+            e = <Linear_Expression> other
+            c = self
 
         cdef PPL_Coefficient cc = PPL_Coefficient_from_pyobject(c)
         cdef Linear_Expression result = Linear_Expression()