The other half of Issue #1580: use short float repr where possible.

Addresses the float -> string conversion, using David Gay's code which
was added in Mark Dickinson's checkin r71663.

Also addresses these, which are intertwined with the short repr
changes:

- Issue #5772: format(1e100, '<') produces '1e+100', not '1.0e+100'
- Issue #5515: 'n' formatting with commas no longer works poorly
    with leading zeros.
- PEP 378 Format Specifier for Thousands Separator: implemented
    for floats.

1 files changed, 23 insertions, 8 deletions

diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index bda8efd..20ab525 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -1016,16 +1016,31 @@ save_float(PicklerObject *self, PyObject *obj)
             return -1;
         if (pickler_write(self, pdata, 9) < 0)
             return -1;
-    }
+   } 
     else {
-        char pdata[250];
-        pdata[0] = FLOAT;
-        PyOS_ascii_formatd(pdata + 1, sizeof(pdata) - 2, "%.17g", x);
-        /* Extend the formatted string with a newline character */
-        strcat(pdata, "\n");
+        int result = -1;
+        char *buf = NULL;
+        char op = FLOAT;
 
-        if (pickler_write(self, pdata, strlen(pdata)) < 0)
-            return -1;
+        if (pickler_write(self, &op, 1) < 0)
+            goto done;
+
+        buf = PyOS_double_to_string(x, 'r', 0, 0, NULL);
+        if (!buf) {
+            PyErr_NoMemory();
+            goto done;
+        }
+
+        if (pickler_write(self, buf, strlen(buf)) < 0)
+            goto done;
+
+        if (pickler_write(self, "\n", 1) < 0)
+            goto done;
+
+        result = 0;
+done:
+        PyMem_Free(buf);
+        return result;
     }
 
     return 0;