- simple function to pick up the mangled type
- pretty-printing is implemented in format-obj.cpp
- also move the demangleCxx()-Function to that location,
it starts to be used for real, outside the test framework
our minimal compiler requirement is gcc-4.9 since the
transition to Debian/Jessie as reference system.
gcc-4.9 is known to treat SFINAE on private fields properly
this is a stripped-down and very leightweight variant
of the well-known enable_if metaprogramming trick.
Providing this standard variant in a header with minimal
dependencies will allow us to phase out boost inclusions
from many further headers. As a plus, our own variant
is written such as to be more conciese in usage
(no "typename" and no acces of an embedded "::type" menber)
now we use boost::format through our own front-end util::_Fmt
solely, which both helps to reduce compilation time and code size,
and gives us a direct string conversion, which automatically
uses any custom operator string() available on arguments.
While desirable as such, I did this conversion now, since
it allows us to get rid of boost::str, which in turn helps
to drill down any remaning uses of our own util::str
allow to pick the bare function signature from any "function like" entity
Note: we're still unsing our own Typelist construct to represent
the function argument types. Since we're now using C++11, this
could be replaced by varargs, and we could get rid of those
various overloads for different numbers of arguments.
Unfortunately this transition is linked to the usage of
argument tuples in our command framework (which could then be
replaced by std::tuple), and this is still a bit of rather
technical work, which I do not want to spend much time on
right now
this was an half hearted attempt to satisfy CLang,
but GCC as keen as a razor insists on these inherited
functions not being accessible --
seems like the time is over, when GCC used to be forgiving
and CLang briliantly precise...
So the conclusion of this "round trip" is: whenever GCC
also starts whining about shadowed overloaded virtual functions,
we'll just switch to "-Wno-overloaded-virtual" and be done with
that pointless discussion.
Since C++11, we have the Java style override specifier,
which does a way better job at spotting signature mismatches
Note: not fixing all relevant warnings.
Especially, the "-Woverloaded-virtual" of Clang defeats the whole purpose
of generated generic interfaces. For example, our Variant type is instantiated
with a list of types the variant can hold. Through metaprogramming, this
instantiation generates also an embedded Visitor interface, which has
virtual 'handle(TY)' functions for all the types in question
The client now may implement, or even partially implement this Visitor,
to retrieve specific data out of given Variant instance with unknown conent.
To complain that some other virtual overload is now shaddowed is besides the point,
so we might consider to disable this warning altogether
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
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>
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 *//**
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
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)
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
Seemingly I've hit a nasty problem here, because PlacementIndex
should return an Placement&, but this is being fetched
after-the fact from within the iterator.
