Having successfully created my first few template definitions I find the
syntax of the definitions curiously unintuitive.  In particular it seems
strange to me that although a template name is always used with a set of
parameters enclosed in <> brackets, it is not declared that way.

That is by contrast with how functions are declared and used as follows:

 int func(a_type a_parm) { ... }

 a_type a_instance;
 int i = func(a_instance);

a template is declared and used as follows:

 template<a_type a_parm> Tclass { ... };

 a_type a_instance;
 Tclass<a_instance> something;

Even though everywhere that Tclass is subsequently used it must be followed
by a supplied parameter enclosed in <> brackets, in the declaration the
parameters are placed after the word template, not after the class name.
To me it would have seemed more intuitive to specify:

 template Tclass<a_type a_parm>  { ... };

Could someone explain the rationale behind the chosen syntax?

Similarly I find the declaration syntax for functions which act on templates
to be cumbersome.  Why do I have to say:

 template<a_type a_parm> int tfunc(Tclass<a_parm> tparm);

when the compiler already knows that Tclass is a template taking a parameter
of type a_type.  That is why can I not just say:

 int tfunc(Tclass<a_parm> tparm);

I have not yet been able to figure out how to declare a friend function
taking template parameters.  When I insert a definition:

 friend operator << (ostream &, const Tclass<a_parm> tparm);

in a template class G++ puts out five lines of warnings.  So I have had to
create a clumsy kluge using a method returning a string which can be used by
the ostream inserter so it does not have to be a friend of the template
class.
--
Jim Cobban   |  jcobban@nortel.ca                   |  Phone: (613) 763-8013
Nortel Networks (MED)                               |  FAX:   (613) 763-5199


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Jim Cobban wrote in message <74pdif$9f7$1@bcarh8ab.ca.nortel.com>...

>Similarly I find the declaration syntax for functions which act on
templates
>to be cumbersome.  Why do I have to say:
>
> template<a_type a_parm> int tfunc(Tclass<a_parm> tparm);
>
>when the compiler already knows that Tclass is a template taking a
parameter
>of type a_type.  That is why can I not just say:
>
> int tfunc(Tclass<a_parm> tparm);


You can say either one, but they have two different meanings.  The first:

template<a_type a_parm> int tfunc(Tclass<a_parm> tparm);

means "Create a function called tfunc that can accept a Tclass based on any
type."

The second:

int tfunc(Tclass<a_parm> tparm);

means "create a function called tfunc that can accept only a Tclass based on
type a_parm"


Here's another example:

void sort(vector<int> list);  //Declares a function that sorts a list of
ints (vector<int>)

template <class VType> void sort( vector<VType> list); //Declares a function
that can sort a list of any type




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