cpython: 3120a988a1a3 (original) (raw)

Mercurial > cpython

changeset 74359:3120a988a1a3

Closes #13761: add a "flush" keyword argument to print(). [#13761]

Georg Brandl georg@python.org
date	Fri, 13 Jan 2012 19:41:25 +0100
parents	87331661042b
children	609482c6710e
files	Doc/library/functions.rst Lib/test/test_print.py Misc/NEWS Python/bltinmodule.c
diffstat	4 files changed, 55 insertions(+), 9 deletions(-)[+] [-] Doc/library/functions.rst 11 Lib/test/test_print.py 26 Misc/NEWS 3 Python/bltinmodule.c 24

line wrap: on

line diff

--- a/Doc/library/functions.rst +++ b/Doc/library/functions.rst @@ -946,7 +946,7 @@ are always available. They are listed h must be of integer types, and y must be non-negative. -.. function:: print([object, ...], *, sep=' ', end='\n', file=sys.stdout) +.. function:: print([object, ...], *, sep=' ', end='\n', file=sys.stdout, flush=False) Print object(s) to the stream file, separated by sep and followed by end. sep, end and file, if present, must be given as keyword @@ -959,9 +959,12 @@ are always available. They are listed h end. The file argument must be an object with a write(string) method; if it

is not present or None, :data:sys.stdout will be used. Output buffering
is determined by file. Use file.flush() to ensure, for instance,
immediate appearance on a screen.

is not present or None, :data:sys.stdout will be used. Whether output
is buffered is usually determined by file, but if the flush keyword
argument is true, the stream is forcibly flushed. +
.. versionchanged:: 3.3

 Added the *flush* keyword argument.[](#l1.24)

.. function:: property(fget=None, fset=None, fdel=None, doc=None)

--- a/Lib/test/test_print.py +++ b/Lib/test/test_print.py @@ -111,6 +111,32 @@ class TestPrint(unittest.TestCase): self.assertRaises(TypeError, print, '', end=3) self.assertRaises(AttributeError, print, '', file='')

def test_print_flush(self):

   # operation of the flush flag[](#l2.8)

```
   class filelike():[](#l2.9)
```
```
       def __init__(self):[](#l2.10)
```
```
           self.written = ''[](#l2.11)
```
```
           self.flushed = 0[](#l2.12)
```
```
       def write(self, str):[](#l2.13)
```

           self.written += str[](#l2.14)

```
       def flush(self):[](#l2.15)
```
```
           self.flushed += 1[](#l2.16)
```

```
   f = filelike()[](#l2.18)
```

   print(1, file=f, end='', flush=True)[](#l2.19)

   print(2, file=f, end='', flush=True)[](#l2.20)

   print(3, file=f, flush=False)[](#l2.21)

   self.assertEqual(f.written, '123\n')[](#l2.22)

   self.assertEqual(f.flushed, 2)[](#l2.23)

   # ensure exceptions from flush are passed through[](#l2.25)

```
   class noflush():[](#l2.26)
```
```
       def write(self, str):[](#l2.27)
```
```
           pass[](#l2.28)
```
```
       def flush(self):[](#l2.29)
```
```
           raise RuntimeError[](#l2.30)
```

   self.assertRaises(RuntimeError, print, 1, file=noflush(), flush=True)[](#l2.31)

+ def test_main(): support.run_unittest(TestPrint)

--- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,9 @@ What's New in Python 3.3 Alpha 1? Core and Builtins ----------------- +- Issue #13761: Add a "flush" keyword argument to the print() function,

used to ensure flushing the output stream. +

Issue #13645: pyc files now contain the size of the corresponding source code, to avoid timestamp collisions (especially on filesystems with a low timestamp resolution) when checking for freshness of the bytecode.

--- a/Python/bltinmodule.c +++ b/Python/bltinmodule.c @@ -1484,15 +1484,15 @@ equivalent to (x**y) % z, but may be mor static PyObject * builtin_print(PyObject *self, PyObject *args, PyObject *kwds) {

static char *kwlist[] = {"sep", "end", "file", 0};

static char *kwlist[] = {"sep", "end", "file", "flush", 0}; static PyObject *dummy_args;

PyObject *sep = NULL, *end = NULL, *file = NULL;

PyObject *sep = NULL, *end = NULL, *file = NULL, *flush = NULL; int i, err; if (dummy_args == NULL && !(dummy_args = PyTuple_New(0)))

```
       return NULL;[](#l4.15)
```
if (!PyArg_ParseTupleAndKeywords(dummy_args, kwds, "|OOO:print",

                                kwlist, &sep, &end, &file))[](#l4.17)

```
   return NULL;[](#l4.18)
```
if (!PyArg_ParseTupleAndKeywords(dummy_args, kwds, "|OOOO:print",

                                kwlist, &sep, &end, &file, &flush))[](#l4.20)
   return NULL;[](#l4.21)

if (file == NULL || file == Py_None) { file = PySys_GetObject("stdout");

@@ -1543,6 +1543,20 @@ builtin_print(PyObject *self, PyObject * if (err) return NULL;

if (flush != NULL) {
```
   PyObject *tmp;[](#l4.29)
```

   int do_flush = PyObject_IsTrue(flush);[](#l4.30)

```
   if (do_flush == -1)[](#l4.31)
```
```
       return NULL;[](#l4.32)
```
```
   else if (do_flush) {[](#l4.33)
```

       tmp = PyObject_CallMethod(file, "flush", "");[](#l4.34)

```
       if (tmp == NULL)[](#l4.35)
```
```
           return NULL;[](#l4.36)
```
```
       else[](#l4.37)
```
```
           Py_DECREF(tmp);[](#l4.38)
```
```
   }[](#l4.39)
```
}

+ Py_RETURN_NONE; }