Re: [Boost-users] Getting metadata of class

On Sat, Dec 12, 2009 at 12:01 AM, Alex Vinokur wrote:

"OvermindDL1" wrote in message news:3f49a9f40912111556w24850c47le205e9f9eb552cf5@mail.gmail.com...

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On Fri, Dec 11, 2009 at 10:45 AM, Alex Vinokur wrote:

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Hi,

Does Boost contain any features to get metadata of classes?

For instance,

Let Foo be some class

class Foo {  int   m_var1;  long*  m_var2]  char   m_var3[100];  dooble  m_var4; };

I would like to get the following info (as vector, file, etc) of its members:

{" m_var1", "int", sizeof (m_var1), offset of (m_var1) }, {" m_var2", "long", "Pointer", sizeof (m_var2), sizeof (base-variable, i.e., long), offset of (m_var2 }, {" m_var3, "char", "array", sizeof (m_var3), sizeof (base-variable, i.e., char), offset of (m_var3 }, {" m_var4", "double", sizeof (m_var4), offset of (m_var4) },

That info I would like to get as a result of some feature (function, ...) applied to class Foo, not to each member of Foo.

C++ is not introspective nor reflective, hence there is no way to do that according to the language spec.  However, you can use Fusion to 'convert' your stucts to a fusion map or vector (depending on if you need names or not)

Is there such a convertor (struct->map) in http://www.boost.org/doc/libs/1_41_0/libs/fusion/doc/html/index.html ?

I am not familiar with boost::fusion.

Not a converter, it is an adapter, it lets you treat the struct as a fusion::map, but you still have to define it, just an easy way of defining it though, then you can use your struct as any normal fusion::map: http://www.boost.org/doc/libs/1_41_0/libs/fusion/doc/html/fusion/adapted/ada...