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Paul Bilokon
Paul Bilokon
Last Activity: Nov 25 '07, 01:46 AM
Joined: Nov 13 '07
Location: London, UK
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  • Paul Bilokon
    replied to Saving hash_map keys in a vector
    in C
    Thanks a lot for your advice, RRick.

    I'm hoping that if I create the vector within a method and then return this vector, the additional copy will be removed by most modern compilers (return value optimisation).

    Is this generally the case in your experience?

    Many thanks,
    Paul
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    • Paul Bilokon
      replied to Calling operator() via a Pointer
      in C
      Thanks a lot, weaknessforcats .

      No, I am not using STL; it's my own custom functor.

      I prefer your syntax, as it emphasises the function call semantics, rather than the "operator() ".

      Many thanks,
      Paul
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      • Paul Bilokon
        replied to Saving hash_map keys in a vector
        in C
        Hi Rick,

        Many thanks for your reply.

        I do indeed feel uneasy about breaking encapsulation.

        As far as the vector of keys is concerned, it's far from ideal, but I would make it part of the contract that this is only a snapshot, or a memento (although not in the strict Design Patterns sense of the word). Then I believe it should be OK.

        This said, does the code that I pasted in my first message...
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        • Paul Bilokon
          started a topic Calling operator() via a Pointer
          in C

          Calling operator() via a Pointer

          Hi all,

          A very simple question, but I couldn't find a definitive answer in the literature. Functors provide you with the function call syntax:
          Code:
          foo(1, 2, 3)
          may be a call to a functor. Now, what if I have a pointer to a functor instead? Is the following syntax the recommended, or perhaps the only, way to call operator() on a functor pointer:
          Code:
          fooPtr->operator()(1, 2, 3)
          Many thanks!

          Regards,...
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          • Paul Bilokon
            replied to Saving hash_map keys in a vector
            in C
            RRick,

            I'm concerned with two use cases.

            First, I need to be able to produce a memento of the map. However, I don't care about the values for this purpose, I only need to remember the keys.

            Second, I have a data structure whose underlying implementation (via composition) is a hash_map. I want to keep this data structure as simple as possible, so I don't want to make it (anywhere near) STL compliant and...
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            • Paul Bilokon
              started a topic Saving hash_map keys in a vector
              in C

              Saving hash_map keys in a vector

              Hi,

              Is there a more elegant and/or efficient way of saving the keys from a hash_map in a vector? Perhaps using assign or other algorithms? The problem, of course, is that we are dealing with an iterator of pairs...

              Code:
              hash_map<string, void *> hashMap;

// ...

vector<string> keys;
keys.reserve(hashMap.size());

hash_map<string, void *>::iterator endIter
              ...
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