especially I've now decided how to handle const-ness:
We're open to all forms of const-ness, the actual usage decides.
const GenNode will only expose a const& to the data values
still TODO is the object builder notation for diff::Record
on a second thought, this "workaround" does not look so bad,
due to the C++11 feature to request the default implementation explicitly.
Maybe we'll never need a generic solution for these cases
This is just a draft for now -- kindof a by-catch, since it is
chep to build that DSL on top of the Rec::Mutator.
This DSL could be of value later, when it comes to define
some configuration data inline, in a copact and clear fashion,
without the need to use a bridge to/from JSON
for the purpose of working out the inner logic, I frequently use the
help of a mindmap -- so why not commiting this alongside? For sure,
it is preliminary and the worked out concepts will be cast in code
and documented on the website. Yet the thought-process leading to
these decisions might be of some interest, at least for myself.
before engaging into the implementation of lib::Record,
I prefer to conduct a round of planning, to get a clearer
view about the requirements we'll meet when extending
our existing list diff to tree structures
Introduce the new term "Fork" at various relevant places
within the documentation. We do not entirely purge the
term "track" though; rather we
- make clear that "Fork" is the entity to build tracks
- use "fork" also synonymous to the "tree of tracks"
This switches the Lumiera UI from GTK-2 to GTK-3
Unfortunately, this move breaks two crucial features, which have been
disabled for now: the display of video and our custom timeline widget.
Since both of these require some reworking, which in fact has already
started, we prefer to do the library and framework switch right away.
to carry out that rather obvious step, I was bound to consider
all the implications of choosing a given layout and handling pattern
for our external structure representation.
Finally, I settled upon the following decisions
- the value space represented within the DataCap is flat, not further structured
- the distinction between "attribute" and "nested object" is merely conceptual
and will be enforced solely by the diff detection / representation protocol
- basically, a nested subtree may appear as an attribute; the difference
between attributes and children lies solely in the way of access and referral:
by-name vs. positional
- it is pointless to save space for the representation of the discriminator ID
- but we can omit any further explicit type tag, because
- we do *not* support programming by switch-on-type, and thus
- we do *not* support full introspection, only a passive type-safety check
- this is *not* a limitation, since we acknowledge that GenNode is a *Monad*
- and the partial function needed within any flatMap implementation
maps naturally onto our Variant-Visitor; thus
- the DataCap can basically just *be* a Variant
- and GenNode has just to supply the neccessary shaffolding
to turn that into a full fledged Monad implementation, including
direct construction by wrapping a value and flatMap with tree walk
This mindmap explains some of the ideas and concepts in more detail.
It can be viewed with the "freeplane" mind mapping software.
("freemind" works as well, but will mess up some of the formatting)
note by the committer: this mindmap was really work in progress.
Christoph shared it with me while in discussion. I'll place it
here in the git history, since it might be interesting to se
how the thoughts evolved. Isn't that what mindmaps are all about?
so yes, it is complicated, and inevitably involves three layers
of indirection. The alternative seems to bind the GUI direcly to
the Session interface -- is there a middle gound?
For the messages from GUI to Proc, we have our commands, based
on PlacementRef entities. But for feeding model updates to the
GUI, whatever I consider, I end up either with diff messages or
an synchronised access to Session attributes, which ties the
responsiveness of the GUI to the Builder operation.
- we use a GenNode element
- this holds a polymorphic value known as DataCap
- besides simple attribute values, this may hold collections of GenNode sub elements
- a special kind of GenNode collection, the Record, is used to represent objects
The purpose of this setup is to enable an external model representation
which is only loosely coupled to the interndal data representation
through the exchange of (tree)diff messages
previously this operation was named 'attach', which an be confused
with attching an object to this location. Indeed, the session interface
even offers such an attach function. By renaming the focus moving
operation into QueryFocus::shift(Scope), this ambiguity is resolved
This is the first step towards a generic backbone to connect
any GUI elements to the session within Proc-Layer.
It is based on a spefic understanding of Model-View-Controller,
which turns the Model-Controller interactions into messages.
Remove some orphaned diagrams and PNG images not actually used
in the TiddlyWiki. Add a page with some hints regarding Bouml
See also #960 -- Bouml has been discontinued and is closed source now
not sure how to proceed with this
This means to discontinue any research into emitting an optimal
diff verb sequence for now and just to document the possible path
I see to reach at such a optimal solution later, when it turns out
to be really necessary performance wise.
Personal note: I arrived at this conclusion while whatching the
New Year fireworks 2014/2015 at the banks of the Isar river in
the centre of the city.
Too sad that 2014 didn't bring us World War III
we want a simple and straight forward way of defining tokens
of the "diff language". Each token is bound to a specific
handler function in the language interpreter interface.
Problem is that likely we'll get a ListDiffLanguage and a TreeDiffLanguage;
after all, I really don't know yet how far to take this whole
diff representation endeavour...
...first step is to design a generic linearised list diff representation.
Basically just need to pull together the theoretical work of the last weeks.
Next steps will be to extend to typed ordered trees.
Actually I arried at the conclusion, that the *receiving* of
a diff representation is actually a typical double-dispatch situation.
This leads to the attempt to come up with a specialised visitor
as standard pattern to handle and apply a diff. Obviously,
we do not want the classical GoF-Visitor, but (yes, we had
that discussion allready) -- well in terms of runtime cost,
we have to deal with at least two indirections anyway;
so now I'm exploring the idea to implement one of these
indirections through a functor object, which at the same time
acts as "Tag" in the diff representation language (instead
of using an enum as tag)
This DSL is usable as wire format for sending
structural change data to another, loosely coupled entity.
A similar format could be used for model serialisation later on.
