Templates and signals

[Ubii]

Hi!

Code:

Header

template <class D>
class Signal
: public QObject
{
public:
void signal(D);
signals:
void send(D);
};

template <class D>
class Signal
: public QObject
{
public:
void signal(D);
signals:
void send(D);
};

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cpp

template <class D> void Signal<D>::signal(D data)
{
emit send(data);
}

template <class D> void Signal<D>::signal(D data)
{
emit send(data);
}

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namespace plot{
Signal* xSignal;
}
//------------------------
plot::xSignal = new Signal();
QObject::connect(plot::xSignal, SIGNAL(send(double)), this, SLOT(notImportant(double)));

namespace plot{
Signal* xSignal;
}
//------------------------
plot::xSignal = new Signal();
QObject::connect(plot::xSignal, SIGNAL(send(double)), this, SLOT(notImportant(double)));

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Everything still works to compile here but in next step something happend

double data = 0;
plot::xSignal->signal(data);

double data = 0;
plot::xSignal->signal(data);

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This code should send a signal to notImportant() like this:
First to "Signal::signal(double)" which send signal to "Signal::send(double)" which is connected to "notImportant(double)".
But I can't compile when I add the last line I got an error message.
Line:

plot::xSignal->signal(data);

plot::xSignal->signal(data);

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Error message is:

error: undefined reference to `Signal<double>::signal(double)''

error: undefined reference to `Signal<double>::signal(double)''

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I am new to templates so it is propably someting wrong there.

Does any of you know whats wrong?

Thanks
Ubi

Sorry for my english, I am from Sweden