[Zope3-dev] Re: registering nameless utilities

[Jim Fulton]

Garrett Smith wrote:
> Jim Fulton wrote:
> 
>> Garrett Smith wrote:
>>
>>> I want to lookup a utility using:
>>>
>>>   zapi.getUtility(iface)
>>>
>>> When I try to register a local utility with a site manager, the UI 
>>> insists I provide a name. (The 'name' attribute of 
>>> IUtilityRegistration is required.)
>>
>>
>>
>> This is undoubtably due to the fact that the schema system, unfotunately,
>> can't tell the differene between an empty string and one that hasn't been
>> provided, even when the minimum string length is 0.
> 
> 
> Ah yes, this debate :-)
> 
> If this truly is a three-state value (!= '', '', and None), we'll need a 
> different widget as a text field can only convey two states.

It's just a string that has zeo or more characters.

> When it comes to registering utilities, is there a practical difference 
> between '' and None?

Yes.  The name is required, but can be ''.

None is not acceptable.

 > I would think we could use one or the other to
> indicate a 'nameless' utility.

There aren't really nameless utilities.  The default name, when one
isn't specified in a getUtility call is ''.

Jim


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