...and I made the decision *not* to consider any kind of
generic properties for now. YAGNI.
UI coding is notorious spaghetti code.
No point in fighting that, it is just the way it is,
because somewhere you're bound to get concrete, hands-on.
...everything working out of the box thus far,
which is remarkable, since I didn't write a single
line of implementation code beyond what's available
as basic bus functionality. So this one just
fell into place
right now, what we actually need here is just some integer,
so the GenNode payload is typed to int (or just to anything
different than a Record, because the Record signals that
we intend to bind, not to invoke the command)
the values.child() call would also do a bounds check,
but only to rise a error::Invalid "index out of bounds".
So now we generate a clear message to indicate that
actually a runtime-checked type mismatch caused this problem
the functionality as such is already covered,
but it seems important enough to warrant a dedicated test.
incidentally, Duration still lacked a default ctor.
Time values are default constructible, yet immutable.
incidentally, this uncovered yet another unwanted narrowing conversion,
namely from double via gavl_time_t to TimeValue or alternatively
from double via FSecs (= rational<long>) to Duration.
As in all the previos cases, actually the compiler is to blame,
and GCC-5 is known to get that one right, i.e. let the SFINAE fail
instead of passing it with a "narrowing conversion" warning.
Note: the real test for command binding with immutable types
can be found in BusTerm_test
Completely removed the nested hierarchy, where
the top-level implementation forwarded to yet another
sub-implementation of the same interface. Rather, this
sub-implementation (OpClosure) is now a mere implementation
detail class without VTable, and without half-baked
re-implementation of the CmdClosure interface. And the
state-switch from unbound to bound arguments is now
implemented as a plain-flat boolean flag, instead of
hiding it in the VTable.
To make this possible, without having to rewrite lots of
tests, I've created a clone of StorageHolder as a
"proof-of-concept" dummy implementation, for the sole
purpose of writing test fixtures. This one behaves
similar to the real-world thing, but cares only
for closing the command operation and omits all
the gory details of memento capturing and undo.
...probably just an omission. TimeValue and Time are
also default constructible, and this makes sense, semantically.
Please note that Time values are *immutable* though.
Only TimeVar can be reassigned. This is so by design
Seems this was part of the confusion when looking at
the inheritance graph: Names where almost reversed
to the meaning. the ArgumentHolder was *not* the
argument holder, but the top level closure. And
the class "Closure" was not "the" Closure, but
just the argument holder. ;-)
still TODO: the ability to use immutable types
within the command framework. In theory, this
shouldn't be had to implement, since we're creating
a new opaque value holder within the command registry
anyway, so it should be sufficient to refrain from
re-assigning a new value tuple. This is relevant,
since e.g. our time framework is built on immutable
value types.
recently, I've introduced this ability in our toString template.
as it turned out, the bool type was not selected by our
boost::format frontend for special treatment, thus showing
just the fallback «bool»
...when the Test-Nexus processes a command binding message.
In the real system of course we do not want to log every bind message.
The challenge here is the fact that command binding as such
is opaque, and the types of the data within the bind message
are opaque as well. Finally I settled on the compromise
to log them as strings, but only the DataCap part;
most value types applicable within GenNode
have a string representation to match.
the rationale is that I deliberately do not want to provide
a mechanism to iterate "over all contents in stringified form".
Because this could be seen as an invitation to process GenNode-
datastructures in an imperative way. Please recall we do not
want that. Users shall either *match* contents (using a visitor),
or they are required to know the type of the contents beforehand.
Both cases favour structural and type based programming over
dynamic run-time based inspection of contents
The actual task prompting me to add this iteration mechanism
is that I want to build a diagnostic, which allows to verify
that a binding message was sent over the bus with some
specific parameter values.
...also for the existing variant, which packages an
arbitrary number of arguments in stringified form
into a given container type. Moreover, the new
form of stringify allows to write util::join
in a clearer way, eliminating the lambda.
...since, semantically, the template param INT is expected to be
"number like", which implies to base the "in range" notion
on a comparison concept (e.g. we might use floating point numbers)
...this was clearly wrong; it went unnoticed just
because the linker cleans up duplicates of
template instantiations. (I'd expect GCC-5
to spot such errors)
very similar to boost::irange, but without heavyweight boost
includes, and moreover based on our Lumiera Forward Iterator concept
Such a inline-range construct makes writing simple tests easy
based on the new generic tuple builder, we're now able to
add a new binding function into the command implementation
machinery, alongside the existing one. As it stands, the
latter will be used rather by unit tests, while the new
access path is what will be actually taken within
the application, when receiving argument binding
messages dispatched via the UI-Bus.
without that check, in theory our test runner will tolerate
a non-zero return value, like throwing or failing an assert,
which is not what we want....
guess these happenend to get in by forgetting to
add this check when switching a test from PLANNED to TEST
since this is a quick-n-dirty workariound, until we're using GCC-5,
I'll err for the simple and safe side and disallow any conversion
from LuidH do some algebraic data type. The problem arises,
sincd LuidH defines a conversion to size_t, which depends
on the platform. So, without checking the actual NumericLimits,
there is no way we can allow a conversion to size_t in a
hard wired way, while disallowing a narrowing conversion
to 32bit unsigned int on 64bit platforms.
And in the end, we don't want conversions from LUID to
numeric values to happen automatically anyway. But of
course we *do* want automatic promotion from a LuidH
to a PlacementRef...
...to avoid warnings when deriving a publicly visible type
from that interface. Newer GCC and CLang versions emit
warnings when details from an anonymous implementation
namespace will leak into type signatures visible outside
the translation unit. In this case here, it's the VTable.
...used in function-closure.hpp to fabricate an argument tuple
for std::bind, for partially closing some function.
This is an attempt to rewrite this somewhat convoluted helper
in a way to fit in with the tuple element picking mechanism
just defined here. Not sure if it's better readable now;
at least it is significantly shorter and omits some
partial specicalisations
because this element picking mechanism for tuples
looks like an instance of something generic.
At least I've written almost the same just some days ago
for the revised version of function-closure, where the
task was to replace a stretch of type arguments in
a given tuple type with a stretch of placeholder types
and then to build a modified ctor, which just fills
in the remaining arguments, while default constructing
the placeholder types. And if we look into the GNU
implementation of std::bind, they're using a similar
concept (with the difference that they're building
a functor object, where we use a type converter)
This refactoring also integrates some generally useful
bits into our standard metaprogramming helper collection
as it turns out, this is a Bug in GCC 4.9 (resolved in 5.x)
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63723
Problem is, GCC emits a warning on narrowing conversions,
while the standard actually disallows them when building
objects from brace-enclosed initialisers.
Unfortunately GCC also emits such a warning from within
a SFINAE context, instead of letting those spurious dangerous
cases fail. So we end up with additional visitor double dispatch
paths, and a lot of additional warnings.
Temporary solution is to hack a custom trait, which
explicitly declares some conversions paths as "narrowing".
Probably this can be implemented in a way more intelligent
way (using std::numeric_limits), but this doesn't seem
worth the effort, since the problem will go away through
compiler evolution eventually.
now we're able to construct suitable parameter values from the
arguments passed embedded in the GenNodes, as is demonstrated with the
EntryID<long> constructed from an ID-string. We really need a full-blown
double-dispatch, since the content type of the concrete GenNode is only
known at runtime (encoded in the RTTI)
There is still the problem with generating some spurions additional
conversion pathes, some of which are narrowing (and thus dangerous).
The copiler emits several warnings here, and all of them are justified.
E.g. it would be possible to pass an int64_t in the GenNode and initialise
a short from it. This might be convenient at times, but I tend rather to
be prohibitive here and thus consider to built in distinct limitations
on the allowed conversions.
working with those variadic index sequences is quite nasty!
Seemingly you'd always need a 2-step type rebinding,
tried several hours now to avoid that, sorry.
What still needs to be settled is the actual problem
of type conversions; we do not want to be confined
just to the small selection of types allowed within
GenNode, rather we want automatic type promotion
when it comes to extracting values into ctor args!
