Using a C++-like iostream Syntax(Python cookbook 2-13)

Problem

You like the C++ approach to I/O, based on ostreams and manipulators (special objects that cause special effects on a stream when inserted in it) and want to use it in your Python programs.

Solution

>>> class IOManipulator(object):
    def __init__(self, function=None):
        self.function = function
    def do(self, output):
        self.function(output)

 

>>> def do_endl(stream):
    stream.output.write('\n')
    stream.output.flush()

    
>>> endl = IOManipulator(do_endl)

 

 1>>> class OStream(object):
 2    def __init__(self, output=None):
 3        if not output:
 4            import sys
 5            output = sys.stdout
 6        self.output = output
 7        self.format = '%s'
 8    def __lshift__(self, thing):
 9        if isinstance(thing, IOManipulator):
            thing.do(self)
        else:
            self.output.write(self.format % thing)
        return self

 

Usage

>>> def example():
        cout = OStream()
        cout << "The avarage of " << 1 << ' and ' << 3 << ' is ' << (1+3)/2 << endl
>>> example()
The avarage of 1 and 3 is 2