From e58567b2f8da44c381e1ec4fcb23ebf9294a5281 Mon Sep 17 00:00:00 2001
From: Lafrite <lafrite@poneyworld.net>
Date: Sat, 28 Mar 2015 09:09:32 +0100
Subject: [PATCH] change op.add and op.sub  for better - management

---
 pymath/operator.py  | 29 ++++++++++++++++++++++++++++-
 test/test_render.py |  4 ++--
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/pymath/operator.py b/pymath/operator.py
index 35e2a19..4d171c2 100644
--- a/pymath/operator.py
+++ b/pymath/operator.py
@@ -281,8 +281,32 @@ class op(object):
         >>> add.__txt__('1','2')
         '1 + 2'
         >>> add.__tex__('1','-2')
-        '1 + (-2)'
+        '1 - 2'
         """
+
+        def _render(self, link, *args):
+            """Global step for __txt__ and __tex__
+
+            :param link: the link between operators
+            :param *args: the operands
+            :returns: the string with operator and operands
+
+            """
+            if args[1][0] == "-":
+                op1 = self.l_parenthesis(args[0], True)
+                op2 = self.r_parenthesis(args[1][1:], True)
+                ans = link.replace('+','-').format(op1 = op1, op2 = op2)
+
+                ans = save_mainOp(ans, self)
+                return ans
+            else:
+                op1 = self.l_parenthesis(args[0], True)
+                op2 = self.r_parenthesis(args[1], True)
+                ans = link.format(op1 = op1, op2 = op2)
+
+                ans = save_mainOp(ans, self)
+                return ans
+
         caract = {
             "operator" : "+", \
             "name" : "add",\
@@ -291,6 +315,7 @@ class op(object):
             "actions" : ("__add__","__radd__"), \
             "txt" :  "{op1} + {op2}",\
             "tex" :  "{op1} + {op2}",\
+            "_render": _render,\
         }
 
         return caract
@@ -321,6 +346,8 @@ class op(object):
             try:
                 if op.mainOp.priority <= self.priority:
                     op = flatten_list(["(", op, ")"])
+                elif op[0] == '-':
+                    op = flatten_list(["(", op, ")"])
             except AttributeError:
                 # op has not the attribute priority
                 try:
diff --git a/test/test_render.py b/test/test_render.py
index 5589a2c..50394b5 100644
--- a/test/test_render.py
+++ b/test/test_render.py
@@ -33,7 +33,7 @@ class TestTexRender(unittest.TestCase):
                 [-2, 3, op.add ],
                 ]
         wanted_render = [ "2 + 3",
-                "2 + ( -3 )",
+                "2 - 3",
                 "-2 + 3",
                 ]
         for (i,e) in enumerate(exps):
@@ -49,7 +49,7 @@ class TestTexRender(unittest.TestCase):
         wanted_render = [ "2 + a",
                 "a + 3",
                 "-2 + a",
-                "a + ( -2 )",
+                "a - 2",
                 ]
         for (i,e) in enumerate(exps):
             rend = tex(e)