After some reconsideration, I decide to stick to the approach with the closures,
but to use a metaprotramming technique to build an inheritance chain.
While I can not decide on the real world impact of storing all those closures,
in theory this approach should enable the compiler to remove all of the
storage overhead. Since, when storing the result into an auto variable
right within scope (as demonstrated in the test), the compiler
sees the concrete type and might be able to boil down the actual
generated virtual function implementations, thereby inlining the
given closures.
Whereas, on the other hand, if we'd go the obvious conventional route
and place the closures into a Map allocated on the stack, I wouldn't
expect the compiler to do data flow analysis to prove this allocation
is not necessary and inline it away.
NOTE: there is now guarantee this inlining trick will ever work.
And, moreover, we don't know anything regarding the runtime effect.
The whole picture is way more involved as it might seem at first sight.
Even if we go the completely conventional route and require every
participating object to supply an implementation of some kind of
"Serializable" interface, we'll end up with a (hand written!)
implementation class for each participating setup, which takes
up space in the code segment of the executable. While the closure
based approach chosen here, consumes data segment (or heap) space
per instance for the functors (or function pointers) representing
the closures, plus code segment space for the closures, but the
latter with a way higher potential for inlining, since the closure
code and the generated virtual functions are necessarily emitted
within the same compilation unit and within a local (inline, not
publickly exposed) scope.
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
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.
sans the implementation of the index lookup table(s)
The algorithm is KISS, a variant of insertion sort, i.e.
worst time quadratic, but known to perform well on small data sets.
The mere generation of the diff description is O(n log n), since
we do not verify that we can "find" out of order elements. We leave
this to the consumer of the diff, which at this point has to scan
into the rest of the data sequence (leading to quadratic complexity)
finally....
The problem is that the C++ "dependent types" defeat the typical
DSL usage, where you define some helper function in a generic
language setup class and mix this language in as superclass.
This is, C++ requires us to refer explicitly to any dependent type,
since, due to possible template specialisations, the parser
can't know if a given symbol is a inherited type or a field.
As a solution, we place the token constructor functors into a
static struct "token", which allows to write e.g. token.insert(xyz)
As decided in beb57cde
this changeset switches our basic list diff language to work
in the style of an insertion sort. Rather than 'pushing back'
out-of-order elements, we scan and bring forward missing elements.
Later, when passing the original location of the elements
fetched this way, a 'skip' verb will help to clean up
possible leftowers, so implementation is possible
(and indeed acomplished) without shifting any other elements.
and this adds a twist: conceptually, we identify the token
with the abstract handler function it represents. But C++
does not allow us to compare member pointers to virtual functions,
for good reason: even two pointers with the "same offset" into
the VTable might end up referring to different implementations,
when bound to instances of different subclasses. This is what
polymorphism is all about.
At this point it seems reasonably, albeit a bit uggly, to use the
diagnostic ID as placeholder instead, and just compare these IDs
instead. We assume that in practice tokens will be defined through
the provided helper macro, which ensures unique identifiers.
basically just a function to pick up the container and element type automatically.
The actual implementation is delegated to the exisiting lib::iter_stl::IterSnapshot
Heureka! found out that the C++ standard library exposes a
cross vendor C++ ABI, which amongst others allows to show
object code names and type-IDs in the language-level, human
readable unmangeld form.
Of course, actual application code should not rely on such a
internal representation, yet it is of tremendous help when
writing and debugging unit tests.
Signed-off-by: Ichthyostega <prg@ichthyostega.de>
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)
Uniform sequence at start of source files
- copyright claim
- license
- file comment
- header guard
- lumiera includes
- library / system includes
Lumiera uses Brittish spelling. Add an according note to the styleguide.
as always, it turned out that the alledged "compiler bug"
rather was my own sloppyness: I forgot properly to undo a change
I made while fighting with compilation problems: the wrapper in
the factory didn't use std::forward, resulting in a plain flat
slicing copy. This, rightfully, triggered the assertion in the
session query resolver (since a sliced Goal can not be dynamic cast
to a specific Query subclass).
TODO: the toolfactory needs a redesign anyway,
this was just placeholder code added in a very early
state of the Lumiera project. We have way better memory
managing facilities at hand now
the use of a custom finisihing functor, which is applied
to any generated product. This can be used for registration,
memory management or similar framework aspects
Implement the first simple usage scenario for the
unified MultiFact template, using variadic templates.
NOTE:
- the obvious solution based on std::forward
triggers strange behaviour in GCC-4.7
- the inline lambda in the test case traps the
CLang-3.0 parster with a segfault. Horay!
...but the whole design looks still overengineered. See #388
- should get rid of the explicit specialisation
- always use a function signature and thus have arguments?
- why inheriting from the wrapper?
still puzzled why this instantiation of MultiFact fails to compile with GCC 4.8
so I'm bound to understand why the types involved
need indeed to be are structured the way they are right now.
previous versions used to resolve this ambiguity in favour of a ctor call,
but now the compiler treats such constructs as function definition;
this is reasonable, since C++11 introduced the notion of a "generalised
initialisation", which is always written as a (possibly empty) list
in braces.
In these specific cases here, we just omit the empty parens
right now we have to defeat an unfortunate static assertion in
the standard library, which is expected to go away in the future.
We use a hack to hijack the problematic definition with the preprocessor,
which requires our header to be first.
NOTE: this header contains a potentially dangerous, temporary workaround
to defeat the static assertion in the default implementation of std::hash,
as shipped with GCC 4.7.x
This assertion turns out to be detrimental all kinds of metaprogramming
based solutions, since it defeats SFINAE. It is expected to be removed
in GCC 4.8
a real fix would be to rewrite the test to collect the retrieved
values and do a structural verification of the results. This
would mean to write a lot of code for such a marginal topic,
which was implemented just for sake of completenes anyway.
Hopefully my lack of "motivation" doesn't backfire eventually ;-)
Conversion means automatic conversion. In our case,
what we need ist the ability to *construct* a bool from
our (function) object -- while functors aren't automatically
convertible to bool. Thus we use one of the new predicates
from <type_traits>
...uncovered by switching to c++11
When invoking an individual test, we used to erase
the 0-th cmdline argument, which happens to be allways
the name of the test being invoked. Yet none of our
tests actually complied to that contract. Rather,
all tests taking arguments access them by 1-based
argument index. Previously, the argument values just
happened to be still in memory at the original location
after erasing the 0st element.
"Fixed" that by changing the contract. Now, the 0th argument
remains in place, but when there are no additional arguments,
the whole cmdline is cleared.
This is messy, but the test runer needs to be rewritten
entirely, the whole API is clumsy and dangerous. Ticket #289
In the November developer meeting, Christian and I agreed that
it's best to remove that offending LUID specifications altogether.
Those embedded LUIDs where one of the issues blocking the transition to C++11
This is a partial and preliminary fix; we had an occasional
numeric overflow on 32bit platforms in some tests.
The complete fix will be to introduce a typedef and then
rework the relevant APIs (which are preliminary anyway,
thus no urge right now)
our front-end for boost::format, the class lib::_Fmt
was lacking an reliable specialisation for long and ulong.
This is due to the notorious problem of these types being
of platform dependant size. As a fix, we're speclialising
explicitly for int16_t, int32_t and int64_t and avoid the
common names 'short', 'int' and 'long' alltogether.
And especially for non-64bit-platform (NONPORTABLE)
we add an explicit specialisation for long
- upgrade the configuration to a current version
- provide a frontpage with cross-links to other documentation
- define a set of modules; relevant classes and files can be
added to these, to create a exploration path for new readers
- fix a lot of errors in documentation comments
- use a custom configuration for the documentation pages
- tweak the navigation, the sections and further arrangements
to make them stand out more prominently, some entity comments
where started with a line of starts. Unfortunately, doxygen
(and javadoc) only recogise comments which are started exactly
with /**
This caused quite some comments to be ignored by doxygen.
Credits to Hendrik Boom for spotting this problem!
A workaround is to end the line of stars with *//**
When a ctor throws, the dtors of sub-objects have already been
invoked. The object itself never existed, strictly speaking,
and thus the dtor must not be invoked. Usually the runtime system
handles matters automatically this way, but since we're doing
here placement new into an array, we're responsible ourselves
This error was uncovered by compiling with Clang.
GCC automatically neutralised this erroneous dtor invocation.
This removes the central clean-up registry;
Instead, now the InstanceHolder manages the lifecycle of
the service instances placed into static memory; the net effect
is that DependencyFactory and instances are created and destroyed
together, locally for each usage scope
We don't need this ability and it pushes us into using a
central registry. This solution turned out to be problematic
when loading dynamic libraries (plug-ins).
this check may look weird, but in fact a similar check in the
old version of the singleton factory helped us spot a problem
with Clang, most likely but of the compiler or runtime system
Clang doesn't allow to declare a private nested class as friend.
This is unfortunate, but likely correct to the letter of the standard.
As a workaround, now we're creating the instances within a static
function of DependencyFactory -- in the end this improves readability
A second issue fixed with this changeset is the scope of the
marker function. Clang is right, this isn't ADL, thus an inline
friend definition is simply not visible outside the class.
lib::Depend<TY> works as drop-in replacement for lib::Singleton<TY>
This changeset removes the convoluted special cases like
SingletonSub and MockInjector.
explanation: we use pthread_once to define a mutex type descriptor,
used to define some of our mutexes as recursive mutexes. Now,
pthread_once relies on a counter stored in a given location;
we used a non-exported global var for this counter.
Unfortunately this ties the mutex initialisation to the static
initialisation of the compilation unit holding this counter variable.
Theoretically it would be possible (we never observed such an incident)
that, during static initialisation, a singleton was brought up,
which requires a class-scoped lock, implemented as recursive mutex.
And it would be possible for this singleton locking to happen prior
to initialisation of the mentioned counter variable.
As a fix, I've moved the counter varialbe into a function scoped
static variable, since that is guaranteed by the C++ runtime system
to be initialised at first usage of the function, irrespective of the
initialisation order of the enclosing compilation units
Clang is more insistent when it comes to enforcing 'protected' visibility.
Since in this case the basic design can be considered sane and optimal, the
only (and obvious) solution is to nest the PIMPL into a default base class
for implementation; this mirrors the structure of the interface.
Compilation with Clang 3.0 (which is available in Debian/stable) fails,
mostly due to some scoping and naming inconsistencies which weren't detected
by GCC. At some instances, Clang seems to have problems to figure out a
perfectly valid type definition; these can be resolved by more explicit
typing (which is preferrable anyway)
using our util::_Fmt front-end helps to reduce the code size,
since all usages rely on a single inclusion of boost::format
including boost::format via header can cause quite some code bloat
NOTE: partial solution, still some further includes to reorganise
now builds for me on Debian-7 Wheezy 64bit
unqualified member functions in dependent base classes not found anymore.
Need to qualify either the class or the instance.
...for the very specific situation when we want
to explore an existing data structure, and the
exploration assumes value semantics.
The workaround then is to use pointers as values.
...attempt to build it based on the monadic iterator primitives.
Only problem is: need to find out relation between nodes
after the fact. In the real usage situation, this
is not a problem, since we have a state object
there, which can track the relation as it is established
the buildsystem will now pick up and link
all test cases according to the layer, e.g.
backend tests will automatically be linked
against the backend + library solely.
This is kind of a workaround to avoid having to maintain two variants.
Explanation: between Boost 1.42 and 1.52 there was the transition to a
reworked version of the filesystem library, itroducing some breaking changes
The new version distinguishes much clearer between the native and the
generic representation of paths -- which becomes relevant when porting
to non-POXIX operating systems.
Actually the intention was to use the generic path representation in all
configuration; currently this distinction is moot, since we're caring
only for POSIX systems.
So the workaround is to use the fsys::path::string() function, which
is available in both versions, but changed meaning to yield the native
string. Later, when able to deprecate older Boost versions, we should
switch to generic_string()
Note: an alternative solution was found by Mike Fisher in 3b39f35
using the compiletime define BOOST_FILESYSTEM_VERSION=2
See also ticket #896
...to extract the syntetic ordering from
DefsRegistry and make that a responsibility
of the (internal) syntactic representation
of the query.
doesn't pass the compiler yet
effectively this joins the two existing lines
of "Query" classes into one systematic representation
Next step would be to move all mutation operations
over to the Query::Builder
time handling is part of the library, while this
convenience shortcut relies on the Advice system,
which resides in the application lib.
To allow this kind of symbolic acces to a grid
entity defined "elesewhere", client code needs
to be linked against liblumieracore.so
especially this allows to use the Advice system
or the query resolvers from within library facilities
to refer to other implementation level services by name
the rules-based configuration and query system
will be located within the core application,
while the concrete implementation facilities
are expected to reside within the session or
maybe also the GUI.
This is kind of a 'rochade' refactoring to resolve
circular library dependencies and confine the parts
dependant on the session and MObjects to the Proc-Layer
And while we're in the middle of chainsaw surgery,
we'll concentrate further query-based facilities
alongside the config-rules within the App core.
This template was a leftover from the early days
of Lumiera development and doesn't provide any
substantial value as an abstraction.
For the more intricate cases, we're using the
lib::MultiFact template, which allows to install
several "fabrication" functions at runtime
especially the exploration stack is pushed down
first successful definition of all the JobPlanning classes
just the framework of classes necessary to pass the compiler;
all implementation is still stubbed
brainstorming how to implement the job planning stage
the idea is to built on top of the IterExplorer,
but have the "stack" of re-evaluation integrated
into a custom type, which exploits the static
node network structure to avoid heap allocations
solution idea: again use a builder function?
the template _Fun started as an internal helper
for function-closure, but seems to be of
general use. Thus move it into meta/function.hpp
(function-closure.hpp is heavyweight)
this enables expansion of a (functional) data structure
until exhaustion -- which is what we need to
build job functors by traversing and expanding
an arbitrarily nested job definition structure
the intention is to use this to simplify
generating render jobs based on the elaborated
dependency network of the render nodes. The key
challenge is to overcome the necessity to
store partially done evaluations as
continuation
the tricky part seems to be how to combine the
source iterators into a new monad instance, while
keeping this "Combinator" Strategy configurable
...just passes the compiler, while still lacking
even the generic implementation of joining
together the source iterators
The idea is to avoid building a data structure
for intermediary results, while still being able
to process a variably sized and arbitrary shaped
set of source data
implemented as extension to the linear combinations.
I decided to use the same "always floor" rule
as employed for time quantisation. Moreover,
we don't support floating point, only rationals
funny enough this possible memory corruption
didn't happen in the unit test, because my
compiler optimised the additional int field
of class SubDummy, making it the same size
of the baseclass. Now matters should be safe.
instead of (ab)using the Timings spect for a
runtime switch, better use the existing
MockInjector facility and thus turn the
mock engine mode into a global switch
this turns out to be the typical usage scenario
for ScopedCollection: a manager object owning
the collection will populate it with specially
crafted components and invoke a member function
for creating the individual components.
This shortcut avoids using tr1::bind alltogether
some basic types are passed on directly;
for those, we use explicit specialisations
in the implementation file, and a traits template
to mark those cases in the header.
custom types with custom string conversion will
be converted to string; everything else
just becomes a type id
these simple utils (length of typelist, maximum size
containment test) are mostly not used in conjunction
with the more elaborate typelist manipulatino utils.
Moreover, we lacked a dedicated unit test
Previously, I've added an additional '&' to be able
to pass references without much ado. This turned out
to be problematic when using constant values at the
invocation site. Well. C++ has really a fixation
ont passing things by value. This is fine, but
doesn't play so well at times when passing smart-ptrs
or similar ref-counting stuff, especially when we just
want to *use* the handle, not store it away.
Essentially the same situation as with for_each
Bottom line: from now on, we need to state the
template parameter for such arguments explicitly,
or just accept the overhead of creating an additional
transient copy of the smart-ptr.
benefits of using a newer compiler, yay!
Explanation: the Link<...> template combines
various policy templates and exposes a set
of functions, which can be bound as functor
into an concrete time::Control instance.
Actually, we need to mix in only the Mutation
baseclass, because we just want to inherit
the privilege to change time values, which
are otherwise immutable. We don't need to
mix in the Mutator template anymore (this
was a leftover from an earlier design)
