Metadata-Version: 1.0
Name: greenlight
Version: 0.1
Summary: UNKNOWN
Home-page: http://concisionandconcinnity.blogspot.com
Author: Ian McCracken
Author-email: ian.mccracken@gmail.com
License: MIT
Description: Greenlight
        ==========
        ``greenlight`` is a powerful decorator that helps you write code using gevent_.
        You can decorate an existing function to run it in a greenlet::
        
            >>> from greenlight import greenlight
            >>> from gevent.greenlet import Greenlet
            >>> @greenlight
            ... def async_squaring(n):
            ...     "An extremely useful function"
            ...     return n**2
            ...
            >>> g = async_squaring(10)
            >>> isinstance(g, Greenlet)
            True
            >>> g.get()
            100
        
        More interestingly, you can chain greenlets inside a greenlit generator
        (similar to Twisted's inlineCallbacks_). This saves boilerplate; one would
        otherwise have to call ``gevent.spawn()`` on each function, then either
        ``link()`` them together, or, perhaps, call ``join()`` or ``get()`` on each one
        and pass the result to the next. With ``greenlight``, you can simply yield to
        get results inline::
        
            >>> @greenlight
            ... def square_thrice(n):
            ...     squared = yield async_squaring(n)
            ...     tothe4th = yield async_squaring(squared)
            ...     tothe8th = yield async_squaring(tothe4th)
            ...
            >>> square_thrice(2).get()
            256
        
        Since a greenlit function always returns a greenlet itself, you can write code
        very similar to the synchronous code you normally would, while still ensuring
        execution order, simply by chaining greenlit functions together. 
        
        You can explicitly return values from the greenlit generator using the
        ``green_return`` function. If ``green_return`` is not used, the result of the
        last greenlet yielded is returned (as in the previous example)::
        
            >>> from greenlight import green_return
            >>> @greenlight
            ... def greater_than_100():
            ...     a = 2
            ...     while True:
            ...         a = yield async_squaring(a)
            ...         if a>100:
            ...             green_return(a)
            ...
            >>> greater_than_100().get()
            256
        
        Error handling works as you would expect::
        
            >>> @greenlight
            ... def something_bad():
            ...     raise Exception('O NOES')
            ...
            >>> @greenlight
            ... def main():
            ...     try:
            ...         hundred = yield async_squaring(10)
            ...         yield something_bad()
            ...     except Exception, e:
            ...         print e
            ...         green_return(None)
            ...
            >>> main().get()
            O NOES
        
        ``greenlight`` normally behaves like gevent.spawn_, in that it starts greenlets for
        you. If you don't want that to happen, you can use ``greenlight_nostart``::
        
            >>> from greenlight import greenlight_nostart as greenlight
            >>> @greenlight
            ... def squared(n):
            ...     return n**2
            ...
            >>> g = squared(4)
            >>> g.started
            False
            >>> g.start(); g.get()
            16
        
        .. _inlineCallbacks: http://twistedmatrix.com/documents/8.1.0/api/twisted.internet.defer.html#inlineCallbacks
        .. _gevent: http://www.gevent.org/
        .. _gevent.spawn: http://www.gevent.org/gevent.html#spawn-helpers
        
Keywords: gevent
Platform: UNKNOWN
