Re: [proto] Held nodes by value for Fundamental types
On 10/04/2012 00:00, Eric Niebler wrote: Thanks. I thought long about whether to handle the fundamental types differently than user-defined types and decided against it. The capture-everything-by-reference-by-default model is easy to explain and reason about. Special cases can be handled on a per-domain basis as needed. By-value capture of fundamental type is the classical way people do it in hand-made ET code. The ad-hoc support in proto is IMHO better as you may really want to capture reference and by the status of Proto of a EDSL toolkit, flexibility is really wanted :). ___ proto mailing list proto@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/proto
Re: [proto] Held nodes by value for Fundamental types
On Tue, Apr 10, 2012 at 3:12 AM, Joel Falcou joel.fal...@lri.fr wrote: On 10/04/2012 00:00, Eric Niebler wrote: Thanks. I thought long about whether to handle the fundamental types differently than user-defined types and decided against it. The capture-everything-by-**reference-by-default model is easy to explain and reason about. Special cases can be handled on a per-domain basis as needed. By-value capture of fundamental type is the classical way people do it in hand-made ET code. The ad-hoc support in proto is IMHO better as you may really want to capture reference and by the status of Proto of a EDSL toolkit, flexibility is really wanted :). Right. I agree with your opinion. Maybe by defining another domain like default_domain_fundamental_by_value (please don't use that name :-)). Thus, the user saves typing as_child if all she/he is looking for is to change this behavior. Regards, Fernando. ___ proto mailing list proto@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/proto
[proto] Held nodes by value for Fundamental types
Hello,
I'm wondering if it would be appropriate to treat the fundamental types
(char, short, int, double, ...) by value, by default.
I wrote this simple piece of code.
I'm not sure if I'm leaving without considering any other implication, but
I think it may be an improvement.
Please, tell me if I am wrong.
Thanks and regards,
Fernando Pelliccioni.
//BEGIN CODE
**
#include boost/proto/proto.hpp
namespace math
{
template typename T
struct dynamic_matrix
{
dynamic_matrix(std::size_t x_lenght, std::size_t y_lenght)
{
//...
}
//Expensive Copy Constructor!!
//...
};
} // namespace math
using namespace boost;
//-
#define BOOST_PROTO_DEFINE_BINARY_OPERATOR_PRIMITIVE(OP, TAG, TRAIT,
DOMAIN, PRIMITIVE)\
templatetypename Left
\
BOOST_FORCEINLINE
\
typename boost::proto::detail::enable_binary
\
DOMAIN
\
, DOMAIN::proto_grammar
\
, BOOST_PROTO_APPLY_BINARY_(TRAIT, Left, PRIMITIVE)
\
, TAG
\
, Left const
\
, PRIMITIVE
\
::type const
\
operator OP(Left left, PRIMITIVE right)
\
{
\
return boost::proto::detail::make_expr_TAG, DOMAIN, Left const ,
PRIMITIVE()(left, right);\
}
\
templatetypename Right
\
BOOST_FORCEINLINE
\
typename boost::proto::detail::enable_binary
\
DOMAIN
\
, DOMAIN::proto_grammar
\
, BOOST_PROTO_APPLY_BINARY_(TRAIT, PRIMITIVE, Right)
\
, TAG
\
, PRIMITIVE
\
, Right const
\
::type const
\
operator OP(PRIMITIVE left, Right right)
\
{
\
return boost::proto::detail::make_expr_TAG, DOMAIN, PRIMITIVE, Right
const ()(left, right); \
}
/**/
//-
namespace math
{
template typename T
struct is_terminal
: mpl::false_
{};
template typename U
struct is_terminaldynamic_matrixU
: mpl::true_
{};
BOOST_PROTO_DEFINE_OPERATORS(is_terminal, proto::default_domain)
BOOST_PROTO_DEFINE_BINARY_OPERATOR_PRIMITIVE(*,
boost::proto::tag::multiplies, is_terminal, proto::default_domain, int)
} //namespace math
int main( /* int argc, char* argv[] */ )
{
using math::dynamic_matrix;
dynamic_matrixint m1(5, 5); //define the x and y size of the
matrix
dynamic_matrixint m2(5, 5);
auto e = m1 + m2; // m1 and m2 are held by reference
auto e2 = m1 * m2; // m1 and m2 are held by reference
auto e3 = m1 * 5; // m1 is held by reference. 5 is
held by value - NO dangling references
auto e4 = proto::deep_copy(m1 * m2);// Expensive copy of m1 and m2
auto e5 = proto::deep_copy(m1 * 5); // Expensive copy of m1
auto e6 = m1 + m2 * 5; // m1 and m2 are held by
reference. 5 is held by value - NO dangling references
auto e7 = m1 + m2 + dynamic_matrixint(5, 5); //dangling reference - I
don't care - Needed deep_copy
return 0;
}
//END CODE
**
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Re: [proto] Held nodes by value for Fundamental types
On 4/9/2012 2:21 PM, Fernando Pelliccioni wrote:
Hello,
I'm wondering if it would be appropriate to treat the fundamental types
(char, short, int, double, ...) by value, by default.
I wrote this simple piece of code.
I'm not sure if I'm leaving without considering any other implication,
but I think it may be an improvement.
Please, tell me if I am wrong.
Thanks. I thought long about whether to handle the fundamental types
differently than user-defined types and decided against it. The
capture-everything-by-reference-by-default model is easy to explain and
reason about. Special cases can be handled on a per-domain basis as needed.
There is a way to change the capture behavior for your domain. The newly
released version of Proto documents how to do this (although the
functionality has been there for a few releases already).
http://www.boost.org/doc/libs/1_49_0/doc/html/proto/users_guide.html#boost_proto.users_guide.front_end.customizing_expressions_in_your_domain.per_domain_as_child
In short, you'll need to define an as_child metafunction in your domain
definition:
class my_domain
: proto::domain my_generator, my_grammar
{
// Here is where you define how Proto should handle
// sub-expressions that are about to be glommed into
// a larger expression.
template typename T
struct as_child
{
typedef unspecified-Proto-expr-type result_type;
result_type operator()( T t ) const
{
return unspecified-Proto-expr-object;
}
};
};
In as_child, you'll have to do this (pseudocode):
if (is_exprT)
return T
else if(is_fundamentalT)
return proto::terminalT::type
else
return proto::terminalT ::type
The metaprogramming is left as an exercise. :-)
--
Eric Niebler
BoostPro Computing
http://www.boostpro.com
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