Doc 11 Containers & Events

Contents

 

Comment about Programming    

Containers    

Events    

 

Copyright ©, All rights reserved. 2005 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA. OpenContent ( http://www.opencontent.org/opl.shtml ) license defines the copyright on this document.

 

References

 

Web Component Development with Zope 3, von Weitershausen

 

 

Comment about Programming

Coding - No Libraries

 

Write all code from scratch

You are in complete control

Only need to know the language

Slow as you write all code from scratch

 

primeCandidate = someInteger

possibleFactor = primeCandidate /2

while possibleFactor > 1:

    if primeCandidate % possibleFactor == 0:

        print primeCandidate, 'has factor', possibleFactor

        break

    possibleFactor = possibleFactor -1

else:

    print primeCandidate, 'is prime'

 

 

 

 

Direct Coding with Libraries

 

Use language and libraries

Faster development using libraries

Still mainly in control

Need to know about libraries (How?)

What happens if library does not

1. Perform action you need

2. Does something you don't want (Perl die)
   

 

import urllib2

    

webPage = urllib2.urlopen(' http://www.eli.sdsu.edu ')

    

print webPage.info()            #print http headers    

    

for line in webPage:                #print out page contents

    print line,

 

 

 

Coding with a Framework

 

Code extends framework

Framework determines

3. What can be done

4. How things are done

 

Framework can save you a lot of time

Need to know what Framework allows before starting

 

import  java.awt.*;

class  HelloApplication  extends  Frame

   {

   public  void  paint(  Graphics  display  )

      {

      int startX  =  30;

      int startY  =  40;

      display.drawString(  "Hello World", startX, startY  );

      }

   }

 

 

 

Coding with a Complex Framework

Zope

 

5. Interfaces

6. ZCML

7. TAL

8. METAL

9. Events

10. Security

11. Adapters

12. Services

13. i18n

14. Metadata

 

One starts working in a complex system

Takes long time to understand the system

Steep learning curve

 

 

Issues above are common in professional programming jobs

 

 

Containers

 

Zope containers

15. Contain things

16. Have a name

17. Have a reference to their container

18. Can restrict what they contain

 

Example - Container that only Holds Books

 

 

 

 

bookstore/interfaces.py

from zope.schema import Field

from zope.app.container.interfaces import IContainer, IContained

from zope.app.container.constraints import ContainerTypesConstraint

from zope.app.container.constraints import ItemTypePrecondition

 

class IBookContainer(IContainer):

 

    def __setitem__(name, object):

        """Add a Book"""

 

    __setitem__.precondition = ItemTypePrecondition(IBook)

 

class IBookContained(IContained):

 

    __parent__ = Field(

        constraint = ContainerTypesConstraint(IBookContainer)

        )

 

 

bookstore/folder.py

from zope.interface import implements

from zope.app.container.btree import BTreeContainer

from zope.app.container.contained import NameChooser

from zope.app.exception.interfaces import UserError

 

from bookstore.interfaces import IBookContainer

 

class BookFolder(BTreeContainer):

    implements(IBookContainer)

 

class BookNameChooser(NameChooser):

 

    def checkName(self, name, object):

        if name != object.title:

            raise UserError(u"Given name & Book title do not match!")

        return \

            super(BookNameChooser, self).checkName(name, object)

 

    def chooseName(self, name, object):

        name = object.title

        print object

        print object.title

        self.checkName(name, object)

        return name

 

 

bookstore/book.py

from persistent import Persistent

from zope.interface import implements

from zope.schema.fieldproperty import FieldProperty

from bookstore.interfaces import IBook, IBookContained

 

from datetime import date

 

class Book(Persistent):

    implements(IBook, IBookContained)

    

    __name__ = __parent__ = None

    

    title = FieldProperty(IBook['title'])

    author =  FieldProperty(IBook['author'])

    date = FieldProperty(IBook['date'])

    

    def asString(self):

        return self.title + ';' + self.author + ';' + str(self.date)

    

    def __fromString(main, string):

        book = Book()

        attributes = string.split(';')

        book.title = unicode(attributes[0])

        book.author = unicode(attributes[1])

        dateStringParts = attributes[2].split('-')

        dateParts = map(int, dateStringParts)

        book.date = date(*dateParts)

        return book

    

    fromString = classmethod(__fromString)

 

 

bookstore/configure.zcml

<configure xmlns=" http://namespaces.zope.org/zope ">

 

<interface

    interface=".interfaces.IBook"

    type="zope.app.content.interfaces.IContentType"

/>

 

<!-- Folder -->

  <content class=".folder.BookFolder">

    <implements

        interface="zope.app.annotation.interfaces.IAttributeAnnotatable

        zope.app.container.interfaces.IContainerNamesContainer"

        />

    <require

        permission="zope.View"

        interface="zope.app.container.interfaces.IReadContainer"

        />

    <require

        permission="zope.ManageContent"

        interface="zope.app.container.interfaces.IWriteContainer"

        />

  </content>

 

  <adapter

      for=".interfaces.IBookContainer"

      provides="zope.app.container.interfaces.INameChooser"

      factory=".folder.BookNameChooser"

      />

<include package=".browser" />

<include package=".text" />

 

</configure>

 

 

bookstore/browser/configure.zcml

<configure

    xmlns=" http://namespaces.zope.org/zope "

    xmlns:browser=" http://namespaces.zope.org/browser "

    >

<browser:menu

        id="alternate_views"

        title="Menu showing different ways to view an object"

        />

 

  <browser:addform

      schema="bookstore.interfaces.IBook"

      content_factory="bookstore.book.Book"

      label="Add a Book"

      name="AddBook.html"

      permission="zope.ManageContent"

      set_before_add="title"

      />

 

  <browser:addMenuItem

      title="Book Folder"

      class="bookstore.folder.BookFolder"

      permission="zope.View"

      />

 

  <browser:containerViews

       for="bookstore.interfaces.IBookContainer"

       contents="zope.ManageContent"

       index="zope.View"

       add="zope.ManageContent"

       />

 

  <browser:resource name="bookstore.css" file="bookstore.css" />

</configure>

 

 

Events

 

Zope supports events

 

Code can be registered to know when events occur

Code is called when the event occurs

Code can trigger an event

 

Zope Events

 

 

 

Sending an Event

 

from zope.interface import implements

from zope.event import notify

from zope.app.annotation.interfaces import IAnnotations

from zope.app.event.objectevent import ObjectAnnotationsModifiedEvent

 

from worldcookery.interfaces import IRating

 

KEY = "worldcookery.rating"

 

class Rating(object):

    implements(IRating)

 

    def rate(self, rating):

        ratings = self.mapping['ratings']

        ratings.append(float(rating))

        self.mapping['average'] = sum(ratings)/len(ratings)

        notify(ObjectAnnotationsModifiedEvent(self.context))

 

 

 

 

Receiving an Event

bookstore/mail/book.py

import email.Charset

email.Charset.add_charset('utf-8', email.Charset.SHORTEST, None, None)

 

from datetime import datetime

from email.MIMEText import MIMEText

from zope.app import zapi

from zope.app.mail.interfaces import IMailDelivery

 

def notifyAdded(book, event):

    return emailNotifications(book)

    

def emailNotifications(book):

 

    subject = "'%(name)s' was added" % {'name': book.title}

    message = MIMEText(book.asString().encode('utf-8'), 'plain', 'utf-8')

    message['Subject'] = subject

    message['From'] = ' whitney@rohan.sdsu.edu '

    message['To'] = ' whitney@cs.sdsu.edu '

    message['Date'] = datetime.now().strftime('%a, %d %b %Y %H:%M:%S %z')

    mailer = zapi.getUtility(IMailDelivery, 'bookstore-delivery')

    mailer.send(" whitney@rohan.sdsu.edu ", [" whitney@cs.sdsu.edu "],

                message.as_string())

 

 

bookstore/mail/configure.zcml

<configure

    xmlns=" http://namespaces.zope.org/zope "

    xmlns:mail=" http://namespaces.zope.org/mail "

    >

 

  <mail:smtpMailer

      name="bookstore-mailer"

      hostname="cs.sdsu.edu"

      port="8025"

      />

  

  <mail:queuedDelivery

      name="bookstore-delivery"

      permission="zope.SendMail"

      queuePath="mail-queue"

      mailer="bookstore-mailer"

      />

 

  <subscriber

      for="bookstore.interfaces.IBook

           zope.app.container.interfaces.IObjectAddedEvent"

      factory=".book.notifyAdded"

      />

</configure>

 

 

 

bookstore/browser/configure.zcml

  <browser:addform

      schema="bookstore.interfaces.IBook"

      content_factory="bookstore.book.Book"

      label="Add a Book"

      name="AddBook.html"

      permission="zope.ManageContent"

       set_before_add="title author date"

      />

 

Added to bookstore/configure.zcml

<include package=".mail" />