python3 print in remaining mip backends

Author: Matthias Koeppe

src/sage/numerical/backends/coin_backend.pyx

@@ -17,6 +17,8 @@ AUTHORS:
 #                  http://www.gnu.org/licenses/
 ##############################################################################
 
+from __future__ import print_function
+
 include "cysignals/memory.pxi"
 include "cysignals/signals.pxi"
 
@@ -1154,7 +1156,7 @@ cdef class CoinBackend(GenericBackend):
             sage: from sage.numerical.backends.generic_backend import get_solver
             sage: p = get_solver(solver = "Coin")   # optional - cbc
             sage: p.problem_name("There once was a french fry") # optional - cbc
-            sage: print p.problem_name()                        # optional - cbc
+            sage: print(p.problem_name())                       # optional - cbc
             There once was a french fry
         """
         if name == NULL:
@@ -1179,7 +1181,7 @@ cdef class CoinBackend(GenericBackend):
             sage: from sage.numerical.backends.generic_backend import get_solver
             sage: p = get_solver(solver = "Coin")                                     # optional - cbc
             sage: p.add_linear_constraints(1, 2, None, names=['Empty constraint 1'])  # optional - cbc
-            sage: print p.row_name(0)                                                 # optional - cbc
+            sage: print(p.row_name(0))                                                # optional - cbc
             Empty constraint 1
         """
         if self.row_names is not None:
@@ -1201,7 +1203,7 @@ cdef class CoinBackend(GenericBackend):
             sage: p = get_solver(solver = "Coin")          # optional - cbc
             sage: p.add_variable(name='I am a variable')   # optional - cbc
             0
-            sage: print p.col_name(0)                      # optional - cbc
+            sage: print(p.col_name(0))                     # optional - cbc
             I am a variable
         """
         if self.col_names is not None:

src/sage/numerical/backends/cplex_backend.pyx

@@ -354,7 +354,7 @@ cdef class CPLEXBackend(GenericBackend):
             sage: from sage.numerical.backends.generic_backend import get_solver # optional - CPLEX
             sage: p = get_solver(solver = "CPLEX")   # optional - CPLEX
             sage: p.problem_name("There once was a french fry") # optional - CPLEX
-            sage: print p.problem_name()                        # optional - CPLEX
+            sage: print(p.problem_name())                       # optional - CPLEX
             There once was a french fry
         """
 
@@ -1534,7 +1534,7 @@ cdef class CPLEXBackend(GenericBackend):
             sage: p.solve()                                            # optional - CPLEX
             2.0
             sage: with open(filename,'r') as f:                        # optional - CPLEX
-            ....:     print f.read()                                   # optional - CPLEX
+            ....:     print(f.read())                                  # optional - CPLEX
             Found incumbent of value ...
             Reduced MIP has 5 rows, 5 columns, and 10 nonzeros.
             ...

src/sage/numerical/backends/generic_backend.pyx

@@ -29,6 +29,8 @@ AUTHORS:
 #                  http://www.gnu.org/licenses/
 #*****************************************************************************
 
+from __future__ import print_function
+
 from copy import copy
 
 cdef class GenericBackend:
@@ -784,7 +786,7 @@ cdef class GenericBackend:
             sage: from sage.numerical.backends.generic_backend import get_solver
             sage: p = get_solver(solver = "Nonexistent_LP_solver")   # optional - Nonexistent_LP_solver
             sage: p.problem_name("There once was a french fry") # optional - Nonexistent_LP_solver
-            sage: print p.problem_name()                        # optional - Nonexistent_LP_solver
+            sage: print(p.problem_name())                       # optional - Nonexistent_LP_solver
             There once was a french fry
         """
 

src/sage/numerical/backends/gurobi_backend.pyx

@@ -26,6 +26,8 @@ Methods
 #                  http://www.gnu.org/licenses/
 ##############################################################################
 
+from __future__ import print_function
+
 include "cysignals/memory.pxi"
 
 from sage.numerical.mip import MIPSolverException
@@ -354,14 +356,14 @@ cdef class GurobiBackend(GenericBackend):
             sage: from sage.numerical.backends.generic_backend import get_solver      # optional - Gurobi
             sage: p = get_solver(solver = "Gurobi")                                   # optional - Gurobi
             sage: p.problem_name("There once was a french fry")                       # optional - Gurobi
-            sage: print p.problem_name()                                              # optional - Gurobi
+            sage: print(p.problem_name())                                             # optional - Gurobi
             There once was a french fry
 
         TESTS::
 
             sage: from sage.numerical.backends.generic_backend import get_solver    # optional - Gurobi
             sage: p = get_solver(solver = "Gurobi")                                 # optional - Gurobi
-            sage: print p.problem_name()                                            # optional - Gurobi
+            sage: print(p.problem_name())                                           # optional - Gurobi
         """
         cdef int error
         cdef char * pp_name[1]

src/sage/numerical/backends/logging_backend.py

@@ -299,7 +299,7 @@ def LoggingBackendFactory(solver=None, printing=True, doctest_file=None, test_me
         ....:                                                  doctest_file=fname))
         4711
         sage: with open(fname) as f:
-        ....:     for line in f.readlines(): print '|{}'.format(line),
+        ....:     for line in f.readlines(): sys.stdout.write('|{}'.format(line))
         |        sage: p = get_solver(solver='GLPK')
         |        sage: p.add_variable(obj=42, name='Helloooooo')
         |        0
@@ -326,7 +326,7 @@ def LoggingBackendFactory(solver=None, printing=True, doctest_file=None, test_me
         ....:                                                 test_method='something'))
         4711
         sage: with open(fname) as f:
-        ....:     for line in f.readlines(): print '|{}'.format(line),
+        ....:     for line in f.readlines(): sys.stdout.write('|{}'.format(line))
         |
         |    @classmethod
         |    def _test_something(cls, tester=None, **options):