Web2py也有意思的

def index():
    """
    example action using the internationalization operator T and flash
    rendered by views/default/index.html or views/generic.html

    if you need a simple wiki simply replace the two lines below with:
    return auth.wiki()
    """
    if not session.counter:
        session.counter = 1
    else:
        session.counter += 1
    #response.flash = T("Welcome to web2py!")
    return dict(message="Hello, Sky from MyApp!", counter=session.counter)

def first():
    form = SQLFORM.factory(Field(‘visitor_name‘, requires=IS_NOT_EMPTY()))
    if form.process().accepted:
        session.visitor_name = form.vars.visitor_name
        redirect(URL(‘second‘))
    return dict(form=form)

def second():
    if not request.function==‘first‘ and not session.visitor_name:
        redirect(URL(‘first‘))
    return dict()