Compiles w/ MSVC (2008), fails with G++ (3.4.4 under cygwin), error
message included. Not sure what I'm doing wrong, I'm assuming the
MSVC is being too permissive as usual...

#include <map>
#include <memory>
using namespace std;

template <class EventT, class StateId> class State;

template <class EventT, class StateId> class StateMachine
{
public:

typedef State<EventT, StateId> StateType;
typedef std::map<StateId, StateType*> StateMap;

void RemoveState(const StateId &stateId);
};

template <class EventT, class StateId>
class State {};

template <class EventT, class StateId>
void StateMachine<EventT, StateId>::RemoveState(
const StateId &stateId)
{
typedef StateMap::iterator StateMapIt; //Errors start here
StateMapIt it;
}

int main(int argc, char *argv[])
{
StateMachine<int, int> x;
x.RemoveState(0);
return 0;
}

.../src/TestWorkspace/TestWorkspace.cpp: In member function `void
StateMachine<Ev
entT, StateId>::RemoveState(const StateId&)':
.../src/TestWorkspace/TestWorkspace.cpp:24: error: expected init-
declarator befor
e "StateMapIt"
.../src/TestWorkspace/TestWorkspace.cpp:24: error: expected `,' or `;'
before "St
ateMapIt"
.../src/TestWorkspace/TestWorkspace.cpp:25: error: `StateMapIt'
undeclared (first
use this function)
.../src/TestWorkspace/TestWorkspace.cpp:25: error: (Each undeclared
identifier is
reported only once for each function it appears in.)
.../src/TestWorkspace/TestWorkspace.cpp:25: error: expected `;' before
"it"
make: *** [../obj/cygwin/debug/TestWorkspace/TestWorkspace.o] Error 1

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cat314159@yahoo.com wrote:
> Compiles w/ MSVC (2008), fails with G++ (3.4.4 under cygwin), error
> message included. Not sure what I'm doing wrong, I'm assuming the
> MSVC is being too permissive as usual...
>
> #include <map>
> #include <memory>
> using namespace std;
>
> template <class EventT, class StateId> class State;
>
> template <class EventT, class StateId> class StateMachine
> {
> public:
>
> typedef State<EventT, StateId> StateType;
> typedef std::map<StateId, StateType*> StateMap;
>
> void RemoveState(const StateId &stateId);
> };
>
> template <class EventT, class StateId>
> class State {};
>
> template <class EventT, class StateId>
> void StateMachine<EventT, StateId>::RemoveState(
> const StateId &stateId)
> {
> typedef StateMap::iterator StateMapIt; //Errors start here
typedef typename StateMap::iterator StateMapIt;
> StateMapIt it;
> }
>

StateMap::iterator is a dependent name, so the compiler needs you to
help it by explicitly telling it that iterator is a type.

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On 2008-08-24 01:58, cat314159@yahoo.com wrote:
> Compiles w/ MSVC (2008), fails with G++ (3.4.4 under cygwin), error
> message included. Not sure what I'm doing wrong, I'm assuming the
> MSVC is being too permissive as usual...
>
> #include <map>
> #include <memory>
> using namespace std;
>
> template <class EventT, class StateId> class State;
>
> template <class EventT, class StateId> class StateMachine
> {
> public:
>
> typedef State<EventT, StateId> StateType;
> typedef std::map<StateId, StateType*> StateMap;
>
> void RemoveState(const StateId &stateId);
> };
>
> template <class EventT, class StateId>
> class State {};
>
> template <class EventT, class StateId>
> void StateMachine<EventT, StateId>::RemoveState(
> const StateId &stateId)
> {
> typedef StateMap::iterator StateMapIt; //Errors start here

Make that "typedef typename StateMap::iterator StateMapIt;"

--
Erik Wikström


[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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cat314159@yahoo.com wrote:
> Compiles w/ MSVC (2008), fails with G++ (3.4.4 under cygwin), error
> message included. Not sure what I'm doing wrong, I'm assuming the
> MSVC is being too permissive as usual...
> template <class EventT, class StateId>
> void StateMachine<EventT, StateId>::RemoveState(
> const StateId &stateId)
> {
> typedef StateMap::iterator StateMapIt; //Errors start here

Try:

typedef typename StateMap::iterator StateMapIt;

Andre'

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cat314159@yahoo.com schrieb:

> Compiles w/ MSVC (2008), fails with G++ (3.4.4 under cygwin), error

> message included. Not sure what I'm doing wrong, I'm assuming the

> MSVC is being too permissive as usual...

>

[snip]

> template <class EventT, class StateId>

> void StateMachine<EventT, StateId>::RemoveState(

> const StateId &stateId)

> {

> typedef StateMap::iterator StateMapIt; //Errors start here

> StateMapIt it;

> }



You make a type that is dependent on a template and you have to use the

'typename' keyword:



typedef typename StateMap::iterator StateMapIt; // will solve your error

I guess





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If the name used depends on a template type as the case shown below
you need to prefix the declaration with the keyword 'typename'. In
this case the name 'something' depends on the type T.

template <typename T>
class A
{
public:
typename T::something x;
};

class B
{
public:
typedef int something;
};

A<B> a;

There's a full explanation here http://www.gotw.ca/gotw/035.htm.

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