Functions in MMObjectBuilder

[Rob Vermeulen]

Hi developers,

I have been thinking about moving the implementation of functions from 
the MMObjectBuilder. This enables removing field functions that should 
not be there anyway (functions such as: dayweek, shortday, 
thisdaycurtime, timesec, etc.etc), and this enables organizations to add 
functions that they want to apply on fields. Some functions that 
actually make sense can be provided to the MMObjectbuilders by providing 
them in a separate classfile.

The idea is to let MMObjectBuilder delegate the executeFuncion 
invocation to the 'function classes'. There are some ways to implement 
this, I will provide 2 ideas, i am curious what you think about this.

1) We can add function classes that extend an interface to invoke the 
function calls (the interface should implement some things like the 
executeFunction method that is already present in MMObjectBuilder). We 
can specify in object.xml which function classes can be used by a 
specific builder to evaluate functions. Defining the function class in 
object.xml will of course enable the function class for all builders.

2) At irc, Daniel was talking about working the other way around. To 
define in the function classes to which builders the functions should 
apply. In this case you can add function classes and without modifying 
your builder configurations the functions can be used. There is already 
some thing like function sets in MMBase (1.7), but i don' t know how 
they work. But maybe it's possible to provide the functions as function 
sets.

Rob