Hi Eric, thank you for your quick response. It is interesting to see that expression like "Domain( [0,1] )" is not allowed. I think the reason is that such expression cannot be transformed in a tree or the transformation is not unique. But why does the code "proto::display_expr(Domain[1,2]);" produce the output: subscript( terminal(domain_tag) ,terminal(2) ) and not subscript( terminal(domain_tag) ,terminal(1) ,terminal(2) ) ? Eric Niebler schrieb:
Kim Kuen Tang wrote:
Hi all,
i have a question and a problem.
The problem is that i would like to write code like: domain=Domain([0,1]*[0,1]); where Domain([0,1]*[0,1]) is an expression created with proto.
But of course this line of code is illegal, because i have to provide the type of this expression Domain([0,1]*[0,1]).
That line of code is illegal because there is no way to make "Domain([0,1]*[0,1])" a valid C++ expression. You need to work on your syntax a little.
So i have to write something like this: Domain([0,1]*[0,1])::type domain=Domain([0,1]*[0,1]); Is this correct?
Now the question: To avoid code like above is this what the macro BOOST_PROTO_AUTO is for? Can i write BOOST_PROTO_AUTO( domain,Domain([0,1]*[0,1]) ); .
Yes, that is what BOOST_PROTO_AUTO is for.