sys displayhook

1import sys
2print('Python version you are using')
3print(sys.version)
4print('Informantion')
5print(sys.version_info)
6
7

1import sys
2
3class ExpressionCounter(object):
4
5    def __init__(self):
6        self.count = 0
7        self.previous_value = self
8
9    def __call__(self, value):
10        print
11        print '  Previous:', self.previous_value
12        print '  New     :', value
13        print
14        if value != self.previous_value:
15            self.count += 1
16            sys.ps1 = '(%3d)> ' % self.count
17        self.previous_value = value
18        sys.__displayhook__(value)
19
20print 'installing'
21sys.displayhook = ExpressionCounter()
22

1def displayhook(value):
2    if value is None:
3        return
4    # Set '_' to None to avoid recursion
5    builtins._ = None
6    text = repr(value)
7    try:
8        sys.stdout.write(text)
9    except UnicodeEncodeError:
10        bytes = text.encode(sys.stdout.encoding, 'backslashreplace')
11        if hasattr(sys.stdout, 'buffer'):
12            sys.stdout.buffer.write(bytes)
13        else:
14            text = bytes.decode(sys.stdout.encoding, 'strict')
15            sys.stdout.write(text)
16    sys.stdout.write("\n")
17    builtins._ = value
18