[Zope3-dev] Proposal to remove simplify zcml

[Steve Alexander]

I keep getting caught out when modifying zcml.

Here's what happens:

   I'm editing a file such as security.zcml.

   <security:protectClass
    name="Zope.App.Security.RolePermissionView.PermissionRoles."
    permission_id="Zope.Security"
    method="roles"
    />


   I want to protect rolesInfo as well as roles, so I edit it this:

   <security:protectClass
    name="Zope.App.Security.RolePermissionView.PermissionRoles."
    permission_id="Zope.Security"
    method="roles, rolesInfo"
    />

   But, when I restart Zope, I get an error:

     Zope.Configuration.xmlconfig.ConfigurationExecutionError: class
     PermissionRoles
     has no attribute 'roles, rolesInfo'
     at line 44 column 54 of lib/python/Zope/App/Security/security.zcml

   Oh dear. I forgot to change the attribute "method" to "methods".

   Going the other way isn't a problem:

   <security:protectClass
    name="Zope.App.Security.RolePermissionView.PermissionRoles."
    permission_id="Zope.Security"
    methods="roles"
    />


I think this kind of modification is a very common use-case. I should be 
able to change just the value, not the attribute name also.

I think we should follow the decision made for TAL. Consider 
tal:attributes. You use "attributes" whether you have one attribute or 
several.

So, for zcml, I propose we say that if there is an attribute that could 
have one value, or a number of values, we have only the plural attribute 
name defined for zcml.


If we agree that this is a good simplification to make, then I volunteer 
to make all the changes necessary.


cc: Jim, because we talked briefly about this at the UK Sprint last month.

--
Steve Alexander