Captcha documentation updated (code examples included, etc).

svn path=/plone.app.discussion/trunk/; revision=37369

plone/app/discussion/browser/captcha.txt

@@ -9,30 +9,36 @@ Introduction
 ------------
 
 When a Captcha plugin (e.g. plone.formwidget.captcha or 
-plone.formwidget.recaptcha) is installed, plone.app.discussion 
-extends the comment form with a Captcha field/widget and a Captcha validator.
+plone.formwidget.recaptcha, collective.akismet) is installed, 
+plone.app.discussion extends the comment form with a Captcha field/widget and a 
+Captcha validator.
 
 The form extender and validator are only registered if there is a plugin 
 installed that claims to provide the "plone.app.discussion-captcha" feature in 
 its configure.zcml file::
 
-    <configure ...
-        xmlns:meta="http://namespaces.zope.org/meta">
+    <configure
+        xmlns:meta="http://namespaces.zope.org/meta"
+        xmlns:zcml="http://namespaces.zope.org/zcml">
+
         <!-- Declare that plone.formwidget.captcha provides a Captcha field that 
              can be used by plone.app.discussion to add a Captcha field to comment 
              forms. -->
         <meta:provides feature="plone.app.discussion-captcha" />
     
-        ...
     </configure>
 
-For an example see:
+.. note::
 
-https://svn.plone.org/svn/plone/plone.formwidget.captcha/trunk/plone/formwidget/captcha/configure.zcml
+  Currently plone.formwidget.captcha, plone.formwidget.recaptcha, and 
+  collective.akismet provide such a feature. If you want to write your own 
+  Captcha plugin, it has to provide this feature as well.
 
-Currently plone.formwidget.captcha and plone.formwidget.recaptcha provide such a
-feature. If you want to write your own Captcha plugin, it has to provide this 
-feature as well.
+.. seealso::
+
+  * https://svn.plone.org/svn/plone/plone.formwidget.captcha/trunk/plone/formwidget/captcha/meta.zcml
+  * https://svn.plone.org/svn/plone/plone.formwidget.recaptcha/trunk/plone/formwidget/recaptcha/meta.zcml
+  * https://svn.plone.org/svn/collective/collective.akismet/trunk/collective/akismet/meta.zcml
 
     
 CaptchaExtender
@@ -45,6 +51,10 @@ plone.formwidget.recaptcha. If you want to write your own Captcha solution, you
 have to override the update() method of the CaptchaExtender or write your own
 CaptchaExtender class.
 
+.. literalinclude:: ../../plone/app/discussion/browser/captcha.py
+   :language: python
+   :pyobject: CaptchaExtender
+
 
 CaptchaValidator
 ----------------
@@ -64,3 +74,26 @@ We do two checks. First we check for a suitable Captcha solution (check for the
 plone.app.discussion-captcha feature, see notes above). Second, we check which 
 Captcha solution is enabled in the discussion control panel and apply the 
 corresponding field validator.
+
+The plone.app.discussion captcha validator always checks for a view with the 
+name of the captcha plugin. For instance, if plone.formwidget.captcha is enabled
+it checks for a "captcha" view.
+
+.. literalinclude:: ../../plone/app/discussion/browser/validator.py
+   :language: python
+   :pyobject: CaptchaValidator
+
+
+.. Writing your own Captcha plugin
+   -------------------------------
+
+   If you want to write your own Captcha plugin, you have to add at least the 
+   following things:
+
+   1) Add your Captcha plugin to the captcha_vocabulary (vocabularies.py) 
+
+   2) Override the update() method of the CapchaExtender class (browser/captcha.py)
+      to show your own Captcha widget.
+
+   3) Override the validate() method of the CaptchaValidator class 
+      (browser/validator.py) to use your own Captcha validator.

plone/app/discussion/browser/validator.py

@@ -67,7 +67,8 @@ class CaptchaValidator(validator.SimpleFieldValidator):
                     raise WrongCaptchaCode
             else:
                 return True
-        
+
+
 # Register Captcha validator for the Captcha field in the ICaptcha Form
 validator.WidgetValidatorDiscriminators(CaptchaValidator, 
                                         field=ICaptcha['captcha'])