recursive tuple -- list using tuples instead of structs

Question

Is it possible to make a list out tuple?

typedef std::tuple<int,node*> node;

A run-time equivalent would be:

struct node {
  int i; 
  node* next
};

Update (1)

Since I got a lot of criticism. I'll expand on the question. Originally I just wanted to keep it simple.

(1) I prefer using tuples to structs. one of the reasons is that I use boost fusion for io, algorithms and meta-programming. structs don't have that. for more information on tuples or an equivalent boost::fusion::vector, see http://www.boost.org/doc/libs/1_55_0/libs/fusion/doc/html/fusion/quick_start.html

(2) Specifically, I use a number of structures similar to this one:

struct SLseg{
    int      edge;         
    Point    lP;           
    Point    rP;          
    SLseg*   above;         
    SLseg*   below;        
};

I don't want to write operator<< for each one of them or use inheritance. boost::fusion's io and pretty-print provide facilities to output the structures given that they are tuples; even if there are stl containers in the tuples.

(3) list is just a simple example. think of having a heterogeneous list where the type is determined using enable_if with some fusion/mpl algorithms.

I'm sure I misunderstand the question, though. So could you please elaborate/clarify? — Jashaszun, Aug 06 '14 at 21:17
Also, what does this have to do with `boost` or `recursion`? — Jashaszun, Aug 06 '14 at 21:18
@Jashaszun I think the problem is that `node` isn't in scope yet at the point of `std::tuple`, so you can't use `node *` as a template parameter... — T.C., Aug 06 '14 at 21:20
what would be the point of the construct? It's the same as the "runtime equivalent", both layout are available compile time. — erenon, Aug 06 '14 at 21:25
@T.C. What do you mean ? `node` could just be forward declared in that case ? — quantdev, Aug 06 '14 at 21:28
@quantdev The code attempts to make `node` an alias of `std::tuple`. You can't forward declare a typedef. — T.C., Aug 06 '14 at 21:30
Your "runtime equivalent" is simply a linked list of integers, why would you need tuples for this ? — quantdev, Aug 06 '14 at 21:45
@Jashaszun boost has mpl and fusion. they work with type. they might have utilities to deal with recursion inside typedef. — kirill_igum, Aug 06 '14 at 21:45
@quantdev, list is just a simple example. there are more complicated structure that would benefit from fusion algorithms. — kirill_igum, Aug 06 '14 at 22:14

score 0 · Answer 1 · edited May 23 '17 at 12:05

0

While not a real solution, you can still turn a struct into a Fusion sequence with FUSION_ADAPT_STRUCT. Also note this question which shows how to properly integrate IO with such an adapted struct.

edited May 23 '17 at 12:05

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answered Aug 06 '14 at 22:28

pmr

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recursive tuple -- list using tuples instead of structs

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