example3.py

from nagare import presentation

class Counter(object):
    
    def __init__(self):
        self.val = 0
        
    def increase(self):
        self.val += 1

    def decrease(self):
        self.val -= 1


@presentation.render_for(Counter)
def render(counter, h, *args):
    h << h.div('Value: ', counter.val)

    h << h.a('++').action(counter.increase)
    h << '|'
    h << h.a('--').action(counter.decrease)

    return h.root


@presentation.init_for(Counter, 'len(url) == 1 and url[0] == "Counter"')
def init(self, url, comp, http_method, request):
    """
    Meaningful URLs are uses to initialize a component with the received URL.
    Other than that application works the same as it used to do.
    """
    value = request.params.get('value')
    if value and value.isdigit():
        self.val = int(value)

app = Counter