"Error: Incomplete type is not allowed"

[ausairman]

I'm getting this error:

Error: Incomplete type is not allowed

on the following line:

double horizon_value::test(brain<horizon_value>& B) {
  neuron<horizon_value>* N_back = B.N->back(); // error here, on "B" 

the "brain" type is declared like this:

template <typename TTrainer>
struct brain {
  // bunch of stuff
  TTrainer* pT; // points to an instance of "horizon_value" 

I suspect it's because I've made a mess of things by having a function inside horizon_value that takes as input something which is templated to horizon_value. Is there a way around this without fundamentally altering the methodology? Note that if I pass "B" by a pointer I get the same error, except it says that an incomplete pointer type is not allowed...

[Catfish2]

http://www.cplusplus.com/forum/general/10931/

Did you #include the file where the brain parameterized class (I love saying that) was defined?

Edit: it does seem you may have the problem of:

1) A class depends on B,
2) B class depends on A,
3) they're included in a particular order,
4) one of them doesn't know anything about the other.

You should be able to "fix" this by writing forward declarations.

[ausairman]

Ah right I got it; the problem was that while I did forward-declare brain<TTrainer>, I didn't define it until after I had defined horizon_value (which included the function that calls brain<horizon_value>). Thanks for the help :)