Re: [Boost-users] multi_array and variants
Alle Meije Wink
> > What I now have is a class bisArray:
> > ...
> > template<typename T>
> > class bisArray: public bisObject {
> > typedef boost::variant
> > < boost::multi_array_ref<T, 1>,
> > boost::multi_array_ref<T, 2>,
> > boost::multi_array_ref<T, 3>,
> > boost::multi_array_ref<T, 4>,
> > boost::multi_array_ref<T, 5>,
> > boost::multi_array_ref<T, 6>,
> > boost::multi_array_ref<T, 7>,
> > boost::multi_array_ref<T, 8>,
> > boost::multi_array_ref<T, 9>
> > > bisArray_t;
> > bisArray_t _bisArray;
> > ...
> >
> > and a class bisImage, which has a bisArray as well as a pointer to the
> > data as read from file (1-dimensional structure):
> > ...
> >
> > template<typename T>
> >
> > class bisImage: public bisObject {
> >
> > public:
> >
> > /** Constructor using existing array data
> > Reformats array as bisImage
> > */
> > bisImage ( T* _data, size_t _dimensions, std::vector<size_t> _sizes
> > ):
> > data(_data), dimensions(_dimensions) {
> >
>
> This code (or You) comes from java or C#, doesn't it? ;-) In C++ it is
> supposed to be this->[...] instead of this.[...]
No, it's C (which doesn't use any of this -not properly at least). The
whole this[...] business was not supposed to be there anyway I
realised.
The reason that I went to boost:: is that I was hoping to get one
class for all data types (using T) and dimensionalities (using
multi_array)
> Second thing: the member storage is initialized with the default constructor
> (which in this case does not exist => error ), and then assigned (below).
>
> I suggest a change to:
> bisImage([...]) : [...], storage( _data, _dimensions, _size ) { [...]
> and remove the assignment from the body of the constructor
>
> Note also: I have read in many places, that you should not use names
> beginning with an underscore (_), because they are reserved for
> compiler/library implementation. One of those places was Herb Sutter's gotw
> series.
Ah! The underscore names come from a library that I tried to imitate
which has successfully incorporated some aspects of boost(it is called
MIMAS). Have not reached the stage of 'nicifying' the code yet...
I moved the storage thing to where you suggested (1 line up) and that
does get rid of lots of errors.
However what I am stuck with seems to be, in essence, still the same thing:
>>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp||In function ‘void bis::bisReadNifti(std::string)’:|
>>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp|102|warning: unused variable ‘testimage’|
>>> /usr/include/boost/variant/variant.hpp||In constructor ‘boost::variant<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19>::variant() [with T0_ = boost::multi_array_ref<unsigned char, 1ul>, T1 = boost::multi_array_ref<unsigned char, 2ul>, T2 = boost::multi_array_ref<unsigned char, 3ul>, T3 = boost::multi_array_ref<unsigned char, 4ul>, T4 = boost::multi_array_ref<unsigned char, 5ul>, T5 = boost::multi_array_ref<unsigned char, 6ul>, T6 = boost::multi_array_ref<unsigned char, 7ul>, T7 = boost::multi_array_ref<unsigned char, 8ul>, T8 = boost::multi_array_ref<unsigned char, 9ul>, T9 = boost::detail::variant::void_, T10 = boost::detail::variant::void_, T11 = boost::detail::variant::void_, T12 = boost::detail::variant::void_, T13 = boost::detail::variant::void_, T14 = boost::detail::variant::void_, T15 = boost::detail::variant::void_, T16 = boost::detail::variant::void_, T17 = boost::detail::variant::void_, T18 = boost::detail::variant::void_, T19 = boost::detail::variant::void_]’:|
>>> /home/amwink/programs/cpp/bis/src/bisarray.hpp|52|instantiated from ‘bis::bisArray<T>::bisArray(T*, size_t, std::vector<long unsigned int, std::allocator<long unsigned int> >) [with T = unsigned char]’|
>>> /home/amwink/programs/cpp/bis/src/bisimage.hpp|33|instantiated from ‘bis::bisImage<T>::bisImage(T*, size_t, std::vector<long unsigned int, std::allocator<long unsigned int> >) [with T = unsigned char]’|
>>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp|126|instantiated from here|
>>> /usr/include/boost/variant/variant.hpp|1198|error: no matching function for call to ‘boost::multi_array_ref<unsigned char, 1ul>::multi_array_ref()’|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|623|note: candidates are: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const typename boost::const_multi_array_ref<T, NumDims, T*>::storage_order_type&, const typename boost::const_multi_array_ref<T, NumDims, T*>::index*, const typename boost::const_multi_array_ref<T, NumDims, T*>::size_type*) [with T = unsigned char, long unsigned int NumDims = 1ul]|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|469|note: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const boost::detail::multi_array::extent_gen<NumDims>&, const boost::general_storage_order<NumDims>&) [with T = unsigned char, long unsigned int NumDims = 1ul]|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|463|note: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const boost::detail::multi_array::extent_gen<NumDims>&) [with T = unsigned char, long unsigned int NumDims = 1ul]|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|417|note: boost::multi_array_ref<unsigned char, 1ul>::multi_array_ref(const boost::multi_array_ref<unsigned char, 1ul>&)|
>>> ||=== Build finished: 1 errors, 1 warnings ===|
So boost.variant now sugegsts that multi_array_ref() is called, a
constructor with no arguments! I don't use that, and I don't even
think it exists (because it produces a multi_array view of an
*existing* C-style array!
The only way I knew to initialise a bisArray was with using a switch
statement -proper C:
switch dims{
case 1: _bisarray=multi_array_ref<T,1> (data, sizes); break;
case 2: _bisarray=multi_array_ref<T,2> (data, sizes); break;
...
}
That is the only way multi_array_ref is called!
Any idea why a problem with the *default* constructor would turn up?
Thanks for your suggestions! My error list already fits on one screen :)
Alle Meije
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Krzysztof Czainski
Dear Kris, thanks for your reply.
You are welcome.
> > template<typename T>
> > class bisArray: public bisObject {
> > typedef boost::variant
> > < boost::multi_array_ref<T, 1>,
> > boost::multi_array_ref<T, 2>,
> > boost::multi_array_ref<T, 3>,
> > boost::multi_array_ref<T, 4>,
> > boost::multi_array_ref<T, 5>,
> > boost::multi_array_ref<T, 6>,
> > boost::multi_array_ref<T, 7>,
> > boost::multi_array_ref<T, 8>,
> > boost::multi_array_ref<T, 9>
> > > bisArray_t;
> > bisArray_t _bisArray;
However what I am stuck with seems to be, in essence, still the same thing:
>>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp||In function ‘void bis::bisReadNifti(std::string)’:|
>>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp|102|warning: unused variable ‘testimage’|
>>> /usr/include/boost/variant/variant.hpp||In constructor ‘boost::variant<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19>::variant() [with T0_ = boost::multi_array_ref<unsigned char, 1ul>, T1 = boost::multi_array_ref<unsigned char, 2ul>, T2 = boost::multi_array_ref<unsigned char, 3ul>, T3 = boost::multi_array_ref<unsigned char, 4ul>, T4 = boost::multi_array_ref<unsigned char, 5ul>, T5 = boost::multi_array_ref<unsigned char, 6ul>, T6 = boost::multi_array_ref<unsigned char, 7ul>, T7 = boost::multi_array_ref<unsigned char, 8ul>, T8 = boost::multi_array_ref<unsigned char, 9ul>, T9 = boost::detail::variant::void_, T10 = boost::detail::variant::void_, T11 = boost::detail::variant::void_, T12 = boost::detail::variant::void_, T13 = boost::detail::variant::void_, T14 = boost::detail::variant::void_, T15 = boost::detail::variant::void_, T16 = boost::detail::variant::void_, T17 = boost::detail::variant::void_, T18 = boost::detail::variant::void_, T19 = boost::detail::variant::void_]’:|
>>> /home/amwink/programs/cpp/bis/src/bisarray.hpp|52|instantiated from ‘bis::bisArray<T>::bisArray(T*, size_t, std::vector<long unsigned int, std::allocator<long unsigned int> >) [with T = unsigned char]’|
>>> /home/amwink/programs/cpp/bis/src/bisimage.hpp|33|instantiated from ‘bis::bisImage<T>::bisImage(T*, size_t, std::vector<long unsigned int, std::allocator<long unsigned int> >) [with T = unsigned char]’|
>>> /home/amwink/programs/cpp/bis/src/bisniftiimage.cpp|126|instantiated from here|
>>> /usr/include/boost/variant/variant.hpp|1198|error: no matching function for call to ‘boost::multi_array_ref<unsigned char, 1ul>::multi_array_ref()’|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|623|note: candidates are: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const typename boost::const_multi_array_ref<T, NumDims, T*>::storage_order_type&, const typename boost::const_multi_array_ref<T, NumDims, T*>::index*, const typename boost::const_multi_array_ref<T, NumDims, T*>::size_type*) [with T = unsigned char, long unsigned int NumDims = 1ul]|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|469|note: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const boost::detail::multi_array::extent_gen<NumDims>&, const boost::general_storage_order<NumDims>&) [with T = unsigned char, long unsigned int NumDims = 1ul]|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|463|note: boost::multi_array_ref<T, NumDims>::multi_array_ref(T*, const boost::detail::multi_array::extent_gen<NumDims>&) [with T = unsigned char, long unsigned int NumDims = 1ul]|
>>> /usr/include/boost/multi_array/multi_array_ref.hpp|417|note: boost::multi_array_ref<unsigned char, 1ul>::multi_array_ref(const boost::multi_array_ref<unsigned char, 1ul>&)|
>>> ||=== Build finished: 1 errors, 1 warnings ===|
So boost.variant now sugegsts that multi_array_ref() is called, a
constructor with no arguments! I don't use that, and I don't even
think it exists (because it produces a multi_array view of an
*existing* C-style array!
The error sais, that the default constructor of multi_array_ref<uchar,1> (which does not exist) is being called from the default constructor of variant.
By default, variant cannot be empty. It's default constructor tries to use the default constructor of the first type on the list. Therefore You have two options:
1) Always initialize the variant with some array,
2) Add a type to the beginning of the list, which will stand for "no value":
#include <boost/none.hpp>
variant< none_t, [...] > bisArray;
Any idea why a problem with the *default* constructor would turn up?
The default ctor of each member is called if You don't specify another means of initialization in the constructor.
Regards, Kris
Alle Meije Wink
This is a problem that I wrote about 4+ months ago (and before that).
I know that many people struggle with it. How to make an array type
that can be 1,2,3, ... n-dimensional (for my specific problem n does
not need to be above 8)
First I hoped that a template definition for dimensionality (similar
to the type template) would be possible --it is not.
Then thanks to some great advice from this list I found a way to make
a sort-of generic class using boost::variant --not really generic as
it lists all the dimensionalities, but it should be able to use
generic visitors to handle addition, subtraction, etc.
I also found out that a default constructor is also always needed
--that was the last post on the subject, see below :).
But now, when I try to compile this to see if I'm on the right track,
my non-default constructor in which I specify the dimensionality d and
dimensions dims (a vector, or an extents[]) it complains that
||=== bis, Debug ===|
/home/amwink/programs/cpp/bis/include/bisArray.hpp|46|error: ‘d’ is not a type|
/home/amwink/programs/cpp/bis/include/bisArray.hpp|46|error: ‘dims’ is
not a type|
/home/amwink/programs/cpp/bis/src/bisArray.cpp|7|error: redefinition
of ‘class bis::bisArray<T, d, dims>’|
/home/amwink/programs/cpp/bis/include/bisArray.hpp|18|error: previous
definition of ‘class bis::bisArray<T, d, dims>’|
||=== Build finished: 4 errors, 0 warnings ===|
The attached code segment is basically as far as I got. I'm not sure
now if d and dims should be templated or not?
To be honest I can't see they they would not both work (in slightly
different ways)?
Anyone have a clue???
Many thanks!
Alle Meije
> Hi Alle,
>
> 2010/11/9 Alle Meije Wink <a.m.wink_at_[hidden]>
>
> > Dear Kris, thanks for your reply.
> >
>
> You are welcome.
>
> > > > template<typename T>
> > > > class bisArray: public bisObject {
> > > > typedef boost::variant
> > > > < boost::multi_array_ref<T, 1>,
> > > > boost::multi_array_ref<T, 2>,
> > > > boost::multi_array_ref<T, 3>,
> > > > boost::multi_array_ref<T, 4>,
> > > > boost::multi_array_ref<T, 5>,
> > > > boost::multi_array_ref<T, 6>,
> > > > boost::multi_array_ref<T, 7>,
> > > > boost::multi_array_ref<T, 8>,
> > > > boost::multi_array_ref<T, 9>
> > > > > bisArray_t;
> > > > bisArray_t _bisArray;
> >
>
> The error sais, that the default constructor of multi_array_ref<uchar,1>
> (which does not exist) is being called from the default constructor of
> variant.
>
> By default, variant cannot be empty. It's default constructor tries to use
> the default constructor of the first type on the list. Therefore You have
> two options:
>
> 1) Always initialize the variant with some array,
> 2) Add a type to the beginning of the list, which will stand for "no value":
> #include <boost/none.hpp>
> variant< none_t, [...] > bisArray;
>
> Any idea why a problem with the *default* constructor would turn up?
> >
>
Larry Evans
[snip]
> But now, when I try to compile this to see if I'm on the right track,
> my non-default constructor in which I specify the dimensionality d and
> dimensions dims (a vector, or an extents[]) it complains that
>
> ||=== bis, Debug ===|
> /home/amwink/programs/cpp/bis/include/bisArray.hpp|46|error: ‘d’ is not a type|
> /home/amwink/programs/cpp/bis/include/bisArray.hpp|46|error: ‘dims’ is
> not a type|
> /home/amwink/programs/cpp/bis/src/bisArray.cpp|7|error: redefinition
> of ‘class bis::bisArray<T, d, dims>’|
> /home/amwink/programs/cpp/bis/include/bisArray.hpp|18|error: previous
> definition of ‘class bis::bisArray<T, d, dims>’|
> ||=== Build finished: 4 errors, 0 warnings ===|
>
> The attached code segment is basically as far as I got. I'm not sure
> now if d and dims should be templated or not?
[snip]
Hi Alle,
Unfortunately, the code which you attached does not contain
the needed #includes. It would help us if you would provide
a complete code example. However, the 'not a type' errors
are because the in the CTOR:
// initialising constructor
bisArray(T, d, dims);
the last 2 arguments:
d, dims
have to type. I assume you meant:
// initialising constructor
bisArray(T, size_t a_dim, size_t* a_extents);
However, that's confusing me because that CTOR, I assume, is used
toe create one of the variant components, and that, according to:
http://www.boost.org/doc/libs/1_45_0/libs
/multi_array/doc/reference.html#multi_array
requires a compile-time value for NumDims, which, of course,
the runtime value, a_dim, is not.
So, it might help also if you provided the body of you CTOR
also to help us see what you're trying to do.
-regards,
Larry