HELP with template casting!
this code: http://pastebin.com/f168570c8
gives the compile error:
test_templates.cpp: In function 'int main(int, char**)':
test_templates.cpp:51: error: expected `(' before 'g'
test_templates.cpp:51: error: expected `)' before ';' token
test_templates.cpp:51: error: invalid const_cast from type 'bar<lab2::Gregorian>' to type 'bar<lab2::Julian>*'
where the Julian and Gregorian are date classes that inherit from Date
How do I "make" the variable j as if it was of <template> type Georgian?
[602 byte] By [
nisse829] at [2007-11-11 11:59:33]
# 1 Re: HELP with template casting!
You cannot do that with a simple cast, most likely. I will not look at the code this way, next time insert the code into your post, I do not click on links in general for security reasons. Anyway, what you can do is make a specialization with an overloaded assignment operator. Or, if the underlying types are similar enough, you can use the base type (for example you can use clock_t and int interchangeably on most platforms). Perhaps both of your types are strings or ints under the hood?
jonnin at 2007-11-11 20:55:39 >
# 2 Re: HELP with template casting!
1.
#include "gregorian.h"
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#include "julian.h"
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#include <time.h>
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#include <assert.h>
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using namespace lab2;
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using namespace std;
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template <class T> struct bar{
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bar<T>(){
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dp = new T;
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}
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bar<T>(int a){
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dp=new T(a);
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}
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bar<T> & operator=(const bar<T> &ref) {
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*dp=*(ref.dp);
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}
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void print(){
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cout << *dp<<endl;
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};
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Date * dp;
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};
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int main(int argc, char **argv)
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{
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time_t a = time(NULL);
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set_k_time(a);
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bar<Julian> j;
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bar<Gregorian> g;
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bar<Gregorian> g2(20);
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cout << "bar<Julian> j:";
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j.print();
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cout <<"bar<Gregorian> g:";
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g.print();
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cout <<"bar<Gregorian> g2:";
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g2.print();
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cout << "** g=g2 **" <<endl;
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g=g2;
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cout <<"g:";
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g.print();
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cout <<"g2;";
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g2.print();
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cout << "** j=g **"<<endl;
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j=const_cast< bar<Julian> *>g;
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cout << "b";
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//b.print();
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cout <<"f";
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//f.print();
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return 0;
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}
