[Rock-dev] Proposed solutions (so far) to the property settings pitfalls

[Sylvain Joyeux]

The problem
===========

    task.config.value = 10

does *not* change the field "value" of property "config" on the task. 
One has to do

    p = task.config
    p.value = 10
    task.config = p

Proposed solutions
==================
0. make task.config.value = 10 transfer the updated property to the
    remote task
1. leaving it as it is
2. require people to use read/write (or get/set) methods to read and
    write the properties. For instance, it could look like

    p = task.read_config
    p.value = 10
    task.write_config(p)

3. make the returned values read-only and allow to provide a
    block to update

    task.config.value = 10 # will raise an exception

    # The following works
    p = task.config.dup
    p.value = 10
    task.config = p

    # and it is equivalent to
    task.config do |p|
       p.value = 10
    end # the property gets written at the end of the block

Thoughts ?


I personally don't like 0 as it involves having partial changes to the 
configuration data structures (which might be very bad if the component 
is currently running).
-- 
Sylvain Joyeux (Dr.Ing.)
Space & Security Robotics

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