On Sun, Jan 23, 2011 at 2:40 AM, TONGARI <tongari95@gmail.com> wrote:
2011/1/23 Vivek <vivek@xmain.com>
2011/1/22 Vivek <vivek_at_[hidden]>
Or alternatively, is there a direct way to initialize a fusion vector?
IIUC, its ctor just do the job, not?
The problem is I don't know the arity or parameter types of the function being called. I just have a source of data (which can be simplified to TYPE data = data_source<TYPE>().pop();) and arbitrary functions being passed in.
Sorry if I missed your point...here comes an idea: Use Fusion's MPL sequences adapters, so you can have:
typedef typename mpl::transform < parameter_types , from_data_source<mpl::_1>
, mpl::back_inserter<mpl::vector<> > >::type data_source_provider; // a MPL sequence
And invoke as:
fs::invoke(f, data_source_provider());
where from_data_source<T> is defined as:
template<class T> struct from_data_source { operator T() const
{ return data_source<T>().pop(); } };
Maybe your data_source<T>() is some singleton for the data source?
That's perfect. I didn't make the connection that a function invocation only requires types that are *convertible* to the argument types, not necessarily exactly the argument types. And the conversion operator can handle fetching the data. And yes, the data source is a singleton. Thanks Vivek