Boost.MultiIndex has been tried in different compilers, with various degrees of success. We list the limitations encountered, along with suitable workarounds when available.
Currently, Boost.MultiIndex cannot be used with any of BCB 6.4 up to BCB 2006. The number of problems encountered during the tests makes it unlikely that future versions of the library can be made to work under these compilers.
No problems have been detected with this compiler. The library fails to compile, however, when Microsoft Visual C++ 6.0 is used as the backend.
No problems have been detected with this compiler. Versions 6.5-042, 7.1-005 and 7.1-006 have been tested.
No problems have been detected with several versions of this compiler starting from 3.2. The following versions have been explicitly tested:
On this platform, GCC is not able to handle debug symbol names whose length
exceeds 32,768 bytes, resulting in the error mips-tfile, ... string
too big. The user may encounter this issue with heavily templatized
code like Boost.MultiIndex, which typically produces long symbol names. The problem
can be overcome by omitting the compiler option -g
(generate debugging
information.) Alternatively, consult the section on
reduction of symbol name lengths for various
applicable workarounds.
Build 4061 of GCC 4.0, shipped with Darwin 8.2 and prior (Mac OS X 10.4.2 and prior), corresponds to a prerelease version of GNU GCC 4.0.0 which introduces a regression bug related to binding of references to temporary objects. This bug precludes the usage of Boost.MultiIndex invariant-checking mode; other than this, Boost.MultiIndex works correctly. The bug is corrected in GCC 4.0 Apple build 5026, which is in sync with the official release of GNU GCC 4.0.0, so the invariant-checking mode is available from this upgrade.
No problems have been detected with this compiler.
Note: This information was last checked for Boost 1.33.1. There is a possibility that changes in Boost since that release have caused problems with this platform.
member
not supported,
refer to the section on
use of
member_offset
for workarounds. member_offset
causes the compiler to emit warnings about the
use of offsetof with non-POD types: these warnings can be suppressed
by setting the compiler option
-qsuppress=1540-1281,
or, alternatively,
by inserting the following preprocessor directive:
#pragma info(nolan)
This latter pragma, however, may also eliminate other warnings not related
to the use of offsetof.
Serialization capabilities are not available as Boost.Serialization is not supported on this platform.
No problems have been detected with this compilers from version 9.0.
member not supported, refer to the section on use of member_offset for workarounds.
When used on top of MSVC++ 7.0 or prior, argument dependent lookup is
disabled by default. This will cause problems with many Boost libraries,
and in particular with the serialization part of Boost.MultiIndex.
Argument dependent lookup is enabled by adding
/Qoption,c,--arg_dep_lookup to the project options.
When used on top of MSVC++ 7.0 or prior, argument dependent lookup is disabled by default. This will cause problems with many Boost libraries, and in particular with the serialization part of Boost.MultiIndex. Argument dependent lookup is enabled by adding /Qoption,c,--arg_dep_lookup to the project options. Other than this, Boost.MultiIndex works without problems. Compiler versions from 8.0 to 9.1 have been tested.
No problems have been detected with this compiler.
Predefined key extractors instantiated on a given type do not accept objects of derived types. For instance:
struct base{}; struct derived:public base{}; ... identity<base> key_extractor; derived x; // not accepted by this compiler: an explicit cast to base is required key_extractor(x);
Other than this, Boost.MultiIndex works without problems under the two operating systems tested: Mac OS and Windows.
Boost.MultiIndex works correctly with versions of this compiler from 9.0 to 9.5, under the two operating systems tested: Mac OS and Windows.
member not supported, refer to the section on use of member_offset for workarounds.
const_mem_fun
and
mem_fun
not supported, refer to the section on
use of
const_mem_fun_explicit
and
mem_fun_explicit
for workarounds.
No support for index retrieval and projection nested types and member functions:
boost::multi_index::multi_index_container
is imported to
namespace boost by means of a using declaration.
MSVC++ 6.0, however, does not properly handle this import. So, instead of
writing:
boost::multi_index_container<...>
use the following:
boost::multi_index::multi_index_container<...>
or else resort to a directive using namespace
boost::multi_index.
The lack of partial template specialization support in MSVC++ 6.0 results in some inconveniences when using composite_key that can be remedied as explained in "composite_key in compilers without partial template specialization".
Due to problems with function template ordering support,
composite_key_compare
and related classes do not accept the notational variations of
operator() where one of the operands is treated as if
included into a tuple of length 1. As a result, the user cannot ever
omit tuple enclosing when specifying the
arguments of lookup operations involving composite keys.
Predefined key extractors instantiated on a given type do not accept objects of derived types. For instance:
struct base{};
struct derived:public base{};
...
identity<base> key_extractor;
derived x;
// not accepted by this compiler: an explicit cast to base is required
key_extractor(x);
MSVC++ 6.0 presents serious limitations for the maximum length of symbol names generated by the compiler, which might result in the linker error LNK1179: invalid or corrupt file: duplicate comdat comdat. To overcome this problem, consult the section on reduction of symbol name lengths for various applicable workarounds.
Under some circumstances, the compiler emits the error C2587: '_U' : illegal use of local variable as default parameter, inside the MSVC internal header <xlocnum>. This problem is a recurrent bug of the compiler, and has been reported in other unrelated libraries, like the Boost Graph Library, Boost.MultiArray, Boost.Regex, CGAL and MySQL++. The error is triggered, though not in a systematic manner, by the use of multi_index_container iterator constructor. Two workarounds exist: the first consists of avoiding this constructor and replacing code like:
multi_index_container<...> s(c.begin(),c.end());
with equivalent operations:
multi_index_container<...> s;
s.insert(c.begin(),c.end());
The second workaround has not been confirmed by the author, but it is given on the Internet in connection with this error appearing in other libraries. Replace line 84 of <xlocnum>
#define _VIRTUAL virtual/span>
with the following:
#define _VIRTUAL
Warning: it is not known whether this replacement can result in unexpected side effects in code implicitly using <xlocnum>.
In general, the extensive use of templates by Boost.MultiIndex puts this compiler under severe stress, so that several internal limitations may be reached. The following measures can help alleviate these problems:
/Gm (Enable Minimal Rebuild.) In these
cases, it is also beneficial to split the project into smaller
subprojects.Boost.MultiIndex works for this configuration. The same limitations apply as in MSVC++ 6.0 with its original Dinkumware standard library. STLport 4.6.2 and 5.0.1 has also been confirmed to work correctly.
It is not possible to use the serialization capabilities of Boost.MultiIndex along with the dynamic version of STLport, as some linking errors result. Use instead the static version of STLport. This bug is fixed in STLport 5.0.
member not supported, refer to the section on use of member_offset for workarounds.
No support for index retrieval and projection nested types and member functions:
boost::multi_index::multi_index_container is imported to
namespace boost by means of a using declaration. MSVC++ 7.0, however, does not properly handle this import. So, instead of
writing:
boost::multi_index_container<...>
use the following:
boost::multi_index::multi_index_container<...>
or else resort to a directive using namespace boost::multi_index.
The lack of partial template specialization support in MSVC++ 7.0
results in some inconveniences when using composite_key
that can be remedied as explained in
"composite_key
in compilers without partial template specialization".
Due to problems with function template ordering support,
composite_key_compare
and related classes do not accept the notational variations of
operator() where one of the operands is treated as if
included into a tuple of length 1. As a result, the user cannot ever
omit tuple enclosing when specifying the arguments of lookup operations
involving composite keys.
Predefined key extractors instantiated on a given type do not accept objects of derived types. For instance:
struct base{};
struct derived:public base{};
...
identity<base> key_extractor;
derived x;
// not accepted by this compiler: an explicit cast to base is required
key_extractor(x);
Boost.MultiIndex works for this configuration. The same issues apply as in MSVC++ 7.0 with its original Dinkumware standard library.
Problems have been reported when compiling the library with the /Gm
option (Enable Minimal Rebuild.) Seemingly, this is due to an
internal defect of the compiler (see for instance
this mention of a similar issue in the Boost Users mailing list.)
If /Gm is turned off, Boost.MultiIndex compiles and runs
without further problems.
Boost.MultiIndex works for this configuration. The same issues apply as in MSVC++ 7.1 with its original Dinkumware standard library.
No problems have been detected with this compiler.
No problems have been detected with this configuration.
No problems have been detected with this compiler.
No problems have been detected with this platform.
The exact compiler version tested was Sun C++ 5.8 Patch 121017-03 2006/07/19.
The option
-library=stlport4 was used to replace the default standard
library with STLport.
member_offset
The member
key extractor poses some problems in compilers
that do not properly support pointers to members as non-type
template arguments, as indicated by the
Boost Configuration Library
defect macro
BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS.
The following compilers have been confirmed not
to work correctly with memberer
MSVC++ 6.0/7.0
Intel C++ 7.0/7.1 for Windows,
VisualAge 6.0 for AIX.
This program can help determine if the compiler
properly supports pointers to members as non-type template parameters:
#include <iostream>
struct pair
{
int x,y;
pair(int x_,int y_):x(x_),y(y_){}
};
template<int pair::* PtrToPairMember>
struct foo
{
int bar(pair& p){return p.*PtrToPairMember;}
};
int main()
{
pair p(0,1);
foo<&pair::x> fx;
foo<&pair::y> fy;
if(fx.bar(p)!=0||fy.bar(p)!=1)std::cout<<"KO"<<std::endl;
else std::cout<<"OK"<<std::endl;
return 0;
}
If the user finds a compiler that does not pass the test, and for which
BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS is not defined,
please report to the Boost developers mailing list.
To overcome this defect, a replacement utility
member_offset
has been provided that does the work of member at the
expense of less convenient notation and the possibility of
non-conformance with the standard. Please consult
the reference for further information on member_offset.
As an example of use, given the class
class A
{
int x;
}
the instantiation member<A,int,&A::x>
can be simulated then
as
member_offset<A,int,offsetof(A,x)>.
For those writing portable code, Boost.MultiIndex provides the ternary macro
BOOST_MULTI_INDEX_MEMBER.
Continuing with the example above, the
expression
BOOST_MULTI_INDEX_MEMBER(A,int,x)
expands by default to
member<A,int,&A::x>
or alternatively to
member_offset<A,int,offsetof(A,x)>
if
BOOST_NO_POINTER_TO_MEMBER_TEMPLATE_PARAMETERS
is defined.
Use of f const_mem_fun_explicitmem_fun_explicit
MSVC++ 6.0 has problems with const
member functions as non-type
template parameters, and thus does not accept the
const_mem_fun key extractor. A simple workaround, fortunately, has been found, consisting
in specifying the type of these pointers as an additional template
parameter. The alternative
const_mem_fun_explicit
extractor adopts this solution; for instance, given the type
struct A
{
int f()const;
};
the extractor const_mem_fun<A,int,&A::f>
can be replaced by const_mem_fun_explicit<A,int,int (A::*)()const,&A::f>. A similar
mem_fun_explicit
class template is provided for non-constant
member functions.
If the user is writing cross-platform code, the selection of either key extractor
is transparently handled by the macro
BOOST_MULTI_INDEX_CONST_MEM_FUN,
so that
BOOST_MULTI_INDEX_CONST_MEM_FUN(A,int,f)
expands by default to
const_mem_fun<A,int,&A::f>
but resolves to
const_mem_fun_explicit<A,int,int (A::*)()const,&A::f>
in MSVC++ 6.0. Non-const member functions are covered by
mem_fun_explicit
and the macro
BOOST_MULTI_INDEX_MEM_FUN
composite_key
in compilers
without partial template specialization
When usingg
composite_keys, lookup is performed by passing tuples of values: this ability is achieved by suitably specializing
the class templates std::equal_to, std::less,
std::greater and boost::hash
for
composite_key_result instantiations so that they
provide the appropriate overloads accepting tuples --and in the case
of
std::less and
std::greater, also partial tuples where only the first components are specified.
In those compilers that do not support partial template specialization,
these specializations cannot be provided, and so
tuple-based lookup is not available by default. In this case, multi_index_container instantiations using composite keys
will work as expected, both for ordered and hashed indices,
except that lookup operations will not accept tuples as an argument.
For ordered indices, the most obvious workaround
to this deficiency involves explicitly specifying the comparison
predicate with
composite_key_compare;
in the case of hashed indices use the analogous
composite_key_equal_to
and
composite_key_hash.
This substitution is tedious as the elementary components for all the constituent key extractors must
be explicitly typed. For this reason, Boost.MultiIndex provides the following replacement
class templates
-
composite_key_result_equal_to,
-
composite_key_result_less,
-
composite_key_result_greater and
-
composite_key_result_hash,
that act as the missing specializations of std::equal_to, std::less,
std::greater and boost::hash for
composite_key_results.
They can be used as follows:
typedef composite_key<
phonebook_entry,
member<phonebook_entry,std::string,&phonebook_entry::family_name>,
member<phonebook_entry,std::string,&phonebook_entry::given_name>
> ckey_t;
typedef multi_index_container<
phonebook_entry,
indexed_by<
ordered_non_unique<
ckey_t,
// composite_key_result_less plays the role of
// std::less<ckey_t::result_type>
composite_key_result_less<ckey_t::result_type>
>,
ordered_unique<
member<phonebook_entry,std::string,&phonebook_entry::phone_number>
>
>> phonebook;
Reduction of symbol name lengths
The types generated on the instantiations off multi_index_containers
typically produce very long symbol names, sometimes beyond the internal limits
of some compilers. There are several techniques to shorten generated symbol
names: these techniques have also the beneficial side effect that resulting error
messages are more readable.
Limitation of maximum number of arguments
The class templates
indexed_by,
tag and
composite_key
accept a variable number of arguments whose maximum number is limited by
internal macros. Even non-used arguments contribute to the final types,
so manually adjusting the corresponding macros can result in a modest reduction
of symbol names.
Limiting maximum number of arguments of some class templates
of Boost.MultiIndex.
class template
limiting macro
default value
default value
(MSVC++ 6.0)
indexed_by
BOOST_MULTI_INDEX_LIMIT_INDEXED_BY_SIZE
20
5
tag
BOOST_MULTI_INDEX_LIMIT_TAG_SIZE
20
3
composite_key
BOOST_MULTI_INDEX_LIMIT_COMPOSITE_KEY_SIZE
10
5
Type hiding
Consider a typical instantiation of multi_index_container:
typedef multi_index_container<
employee,
indexed_by<
ordered_unique<identity<employee> >,
ordered_non_unique<member<employee,std::string,&employee::name> >,
ordered_unique<member<employee,int,&employee::ssnumber> >
>
> employee_set;
Then, for instance, the type
employee_set::nth_type<0>::type
resolves to the following in GCC:
boost::multi_index::detail::ordered_index<
boost::multi_index::identity<employee>,
std::less<employee>,
boost::multi_index::detail::nth_layer<
1, employee,
boost::multi_index::indexed_by<
boost::multi_index::ordered_unique<
boost::multi_index::identity<employee>, mpl_::na, mpl_::na
>,
boost::multi_index::ordered_non_unique<
boost::multi_index::member<employee, std::string, &employee::name>,
mpl_::na, mpl_::na
>,
boost::multi_index::ordered_unique<
boost::multi_index::member<employee, int, &employee::ssnumber>,
mpl_::na, mpl_::na
>,
mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na
>,
std::allocator<employee>
>,
boost::mpl::vector0<mpl_::na>,
boost::multi_index::detail::ordered_unique_tag
>
It can be seen that a significant portion of the type name is contributed by
the
indexed_by<...>
part, which is nothing but an expanded
version of the index specifier list provided in the definition of
employee_set. We can prevent this very long name from appearing
in the final type by encapsulating it into another, shorter-named construct:
// reducing symbol names through type hidingg
// type hide the index spexifier list within employee_set_indices
struct employee_set_indices:
indexed_by<
ordered_unique<identity<employee> >,
ordered_non_unique<member<employee,std::string,&employee::name> >,
ordered_unique<member<employee,int,&employee::ssnumber> >
>
{};
typedef multi_index_container<
employee,
employee_set_indices
> employee_set;
employee_set_indices
works as a conventional
typedef
in all respects, save for a detail: its name does not explicitly
include the information contained in the
indexed_by instantiation.
Applying this technique,
employee_set::nth_type<0>::type
now becomes:
boost::multi_index::detail::ordered_index<
boost::multi_index::identity<employee>,
std::less<employee>,
boost::multi_index::detail::nth_layer<
1, employee,
employee_set_indices,
std::allocator<employee>
>,
boost::mpl::vector0<mpl_::na>,
boost::multi_index::detail::ordered_unique_tag
>
which is considerably shorter than the original, and also more
easily parsed by a human reader. Type hiding would not work if, instead of
making employee_set_indices a derived
struct of
indexed_by<...>, we had defined it as a typedef:
typedefre syntactic aliases and usually get expanded
by the compiler before doing any further type handling.
Type hiding techniques can also be applied to composite_key
intantiations,
which often contribute a great deal to symbol name lengths.
Revised October 16th 2006 © Copyright 2003-2006 Joaquín M López Muñoz.
Distributed under the Boost Software
License, Version 1.0. (See accompanying file LICENSE.html or copy at
http://www.boost.org/LICENSE_1_0.txt )