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Rainer Deyke
Demon Hunter
Joined: 05 Jun 2002
Posts: 672
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 Posted: Thu Jun 19, 2003 1:39 am Post subject: |
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'std::vector<bool>' is not a true 'std::vector'. It is not even a true container. It is a specialization that stores eight bools to a byte. Because of this its 'reference_type' is not 'bool&'.
There are two ways of fixing your class, both with advantages and disadvantages. Compare:
| Code: |
class EventList {
vector<bool> events;
vector<bool>::reference_type operator[] ( int index ) {
return events [ index ];
}
};
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| Code: |
class EventList {
struct wrapped_bool {
bool value;
};
vector<wrapped_bool> events;
bool& operator[] ( int index ) {
return events[index].value;
}
};
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The first implementation is more space-efficient and generally easier to write. The second implementation gives you a true 'bool&' which makes it easier to use.
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PoV
Milk Maid
Joined: 09 Jun 2002
Posts: 42
Location: DrAGON MaX (Canada)
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| Posted: Thu Jun 19, 2003 2:55 am Post subject: |
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Heh, or if you don't use Visual Studio (or even if you do), you should use "vector< bool >::reference" not "vector< bool >::reference_type". Of course, if you don't care for portability, then by all means use reference_type, 'cause I doubt they'll depreciate it.
I shouldn't have to mention the operator should be public.. heh...
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grenideer
Wandering Minstrel
Joined: 28 May 2002
Posts: 149
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| Posted: Thu Jun 19, 2003 6:00 am Post subject: |
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Inheriting doesn't give access to private data in the base only to protected.
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ack! did I say that? :)
_________________
Diver Down
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Jihgfed Pumpkinhead
Stephen Hawking
Joined: 21 Jan 2003
Posts: 259
Location: Toronto, Canada
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| Posted: Thu Jun 19, 2003 10:51 pm Post subject: Thanks for vector<bool> Help |
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Alright, thanks a lot for the help, everybody. I think I've got a handle on this now. Thanks again.
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