Gokulakannan Somasundaram escribió:
Hi Joaquín ,
I am extremely sorry, i missed your mail. First of all thanks
a lot for replying.
I have fixed the issue for now. But i am actually explaining the issue
i had. Please take a shot at it.
Say i have an object and i have created multi index on some
members of the object. Now since,
this is being used in a multi-threaded code, i will acquire a mutex on
the whole multi-index, only if i have
updated those attributes involved in the multi-index build. Else i
won't take the mutex.
Now my problem is, i have multi-indexed many such classes.
what is the best way to check whether
the updated attribute is part of multi-index. Currently we have
written a python code which scans the C++
files and creates a list of attribute numbers ( each member attribute
has a number associated with it ).
Whenever there is an update, we check against the list produced by the
python code in C++.
My question was if there is a way to do this within C++ itself.
If we had the following metafunction to check whether a particular
key extractor is used with a multi_index_container or not:
template<typename KeyExtractor,typename MultiIndexContainer>
struct is_key_extractor_of{};
then it is easy to know at compile time if a particular member of a class is
referenced by a member<...> key extractor (composite keys are harder and
left as an exercise to the reader):
struct A
{
int a,b,c,d,e,f;
};
typedef multi_index_container<
int,
indexed_by<
ordered_unique<member<A,int,&A::a> >,
sequenced<>,
>
> multi_t;
BOOST_MPL_ASSERT ((is_key_extractor_of<member<A,int,&A::a>,multi_t>));
BOOST_MPL_ASSERT_NOT((is_key_extractor_of<member<A,int,&A::e>,multi_t>));
Full code provided in the attachment. Does this help to implement your
scenario?
Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo
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