SG::DataBucketTrait< T, U > Struct Template Reference

Metafunction to find the proper DataBucket class for T. More...

#include <DataBucketTraitFwd.h>

Collaboration diagram for SG::DataBucketTrait< T, U >:

Public Types
using	base1 = SG::BaseType_t< typename SG::Bases< T >::bases::Base1 >
using	deflt = std::type_identity< SG::DataBucket< U > >
using	recurse = DataBucketTrait< base1, U >
using	type = typename std::conditional_t< has_base, deflt, recurse >::type

Static Public Member Functions
static void	init ()
	Initialization hook. A no-op by default. More...

Static Public Attributes
static constexpr bool	has_base = std::is_same_v<base1, SG::NoBase>

Detailed Description

template<class T, class U>
struct SG::DataBucketTrait< T, U >

Metafunction to find the proper DataBucket class for T.

See in Storable_conversions.h for full documentation.

Here's what we're trying to do.

The default DataBucket class for T is SG::DataBucket<T>.

However, if T is a DataVector or DataList, then we want to use instead SG::DVLDataBucket<T>.

Further, if T derives from DataVector or DataList (as declared by SG_BASES), then we also want to use SG::DVLDataBucket<T>.

Further, we don't want this code to depend on DataVector or SG::DVLDataBucket. That behavior is enabled only by including the appropriate DataVector/DataList headers.

So, we handle this with the following metafunction. (By saying that this is a ‘metafunction’, it means that the result is given by the nested type type.) The T argument is the type we're testing, and U is the top-level type that was given to the original invocation of DataBucketTrait. If T has no bases (according to SG::Bases), we return SG::DataBucket<U>. Otherwise, we apply ourselves recursively to the first base class.

Other packages can then specialize this to change the behavior.

We don't really try to handle multiple bases. In principle, we could loop over them. But it seems that that's not really needed, so i don't want to pull in the extra overhead unnecessarily.

This class also defines a real static function init(). This is called from fromStorable. It can be used to force instantiation of reflection information.

Definition at line 30 of file DataBucketTraitFwd.h.

Member Typedef Documentation

base1

template<class T , class U >

using SG::DataBucketTrait< T, U >::base1 = SG::BaseType_t<typename SG::Bases<T>::bases::Base1>

Definition at line 130 of file StorableConversions.h.

deflt

template<class T , class U >

using SG::DataBucketTrait< T, U >::deflt = std::type_identity<SG::DataBucket<U> >

Definition at line 136 of file StorableConversions.h.

recurse

template<class T , class U >

using SG::DataBucketTrait< T, U >::recurse = DataBucketTrait<base1, U>

Definition at line 139 of file StorableConversions.h.

type

template<class T , class U >

using SG::DataBucketTrait< T, U >::type = typename std::conditional_t<has_base, deflt, recurse>::type

Definition at line 142 of file StorableConversions.h.

Member Function Documentation

init()

template<class T , class U >

static void SG::DataBucketTrait< T, U >::init ( )

inlinestatic

Initialization hook. A no-op by default.

Definition at line 145 of file StorableConversions.h.

{}

Member Data Documentation

has_base

template<class T , class U >

constexpr bool SG::DataBucketTrait< T, U >::has_base = std::is_same_v<base1, SG::NoBase>

staticconstexpr

Definition at line 133 of file StorableConversions.h.

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The documentation for this struct was generated from the following files:

• DataBucketTraitFwd.h
• StorableConversions.h