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John Torjo
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 Posted: Tue Oct 26, 2004 10:51 pm Post subject: typedefing ahead |
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Consider this code:
#include <iostream>
template<int i> struct test {
test() { std::cout << "general" << std::endl; }
};
typedef test<0> test_zero;
typedef test<1> test_one;
template<> struct test<0> {
test() { std::cout << "zero" << std::endl; }
};
int main() {
test_zero zero;
test_one one;
}
// output:
// zero
// general
In this case, test_zero, is an alias for test<0>, even though I later
specialize test<0>.
By reading the standard, it looks to me that this is perfectly legal,
and does exactly what it should.
(also, tested it with vc71, gcc3.3.1, como, and works)
Am I right about this - is this standard behavior?
Or is there some corner in the standard that forbids this?
Thanks.
Best,
John
John Torjo, Contributing editor, C/C++ Users Journal
-- "Win32 GUI Generics" -- generics & GUI do mix, after all
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Bob Hairgrove
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| Posted: Wed Oct 27, 2004 2:03 pm Post subject: Re: typedefing ahead |
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On 26 Oct 2004 18:51:36 -0400, [email]jtorjo (AT) yahoo (DOT) com[/email] (John Torjo) wrote:
| Quote: | Consider this code:
#include <iostream
template
test() { std::cout << "general" << std::endl; }
};
typedef test<0> test_zero;
typedef test<1> test_one;
template<> struct test<0> {
test() { std::cout << "zero" << std::endl; }
};
int main() {
test_zero zero;
test_one one;
}
// output:
// zero
// general
In this case, test_zero, is an alias for test<0>, even though I later
specialize test<0>.
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Yes. A typedef is an alias, not a new name. It shouldn't cause test<0>
to become instantiated, AFAIK, because it hasn't yet been used.
| Quote: | By reading the standard, it looks to me that this is perfectly legal,
and does exactly what it should.
(also, tested it with vc71, gcc3.3.1, como, and works)
|
I will always vote with como <g>.
--
Bob Hairgrove
[email]NoSpamPlease (AT) Home (DOT) com[/email]
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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Nicola Musatti
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| Posted: Thu Oct 28, 2004 1:58 pm Post subject: Re: typedefing ahead |
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[email]jtorjo (AT) yahoo (DOT) com[/email] (John Torjo) wrote in message news:<c638aac5.0410260117.2670aba6 (AT) posting (DOT) google.com>...
| Quote: | Consider this code:
#include <iostream
template
test() { std::cout << "general" << std::endl; }
};
typedef test<0> test_zero;
[...]
In this case, test_zero, is an alias for test<0>, even though I later
specialize test<0>.
By reading the standard, it looks to me that this is perfectly legal,
and does exactly what it should.
(also, tested it with vc71, gcc3.3.1, como, and works)
|
I can't give you a final answer, but considering that the following is valid:
template<int i> struct test;
typedef test<0> test_zero;
I'm pretty sure that what you do is just as valid.
Cheers,
Nicola Musatti
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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