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static constructors and destructors in C++

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  • N Nish Nishant

    [removed]

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    Atul Dharne
    wrote on last edited by
    #8

    Static Constructor...The idea is kinda weird :-)..How are they implemented in C#? Atul Sonork 100.13714 netdiva

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    • M Michael Dunn

      There is no such thing. You'd do something like:

      // In foo.h:
      class C
      {
      public:
      static int m_stat_var;
      static int stat_func() { return 1; }
      };

      // In foo.cpp:
      int C::m_stat_var = C::stat_func();

      --Mike-- "There are only a limited number of jobs where they will ask to see the sausage. Most of them are in movies."  -- Christian Graus, 2/11/2002 My really out-of-date homepage Sonork - 100.10414 AcidHelm Big fan of Alyson Hannigan.

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      Nish Nishant
      wrote on last edited by
      #9

      [removed]

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      • N Nish Nishant

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        Michael Dunn
        wrote on last edited by
        #10

        That's Just The Way It's Done. :) It's similar to the situation when you write "extern int n;" in a header file. You still need to actually declare the variable "int n;" in a .cpp file. --Mike-- "There are only a limited number of jobs where they will ask to see the sausage. Most of them are in movies."  -- Christian Graus, 2/11/2002 My really out-of-date homepage Sonork - 100.10414 AcidHelm Big fan of Alyson Hannigan.

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        • M Michael Dunn

          That's Just The Way It's Done. :) It's similar to the situation when you write "extern int n;" in a header file. You still need to actually declare the variable "int n;" in a .cpp file. --Mike-- "There are only a limited number of jobs where they will ask to see the sausage. Most of them are in movies."  -- Christian Graus, 2/11/2002 My really out-of-date homepage Sonork - 100.10414 AcidHelm Big fan of Alyson Hannigan.

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          Nish Nishant
          wrote on last edited by
          #11

          [removed]

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          • N Nish Nishant

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            Michael Dunn
            wrote on last edited by
            #12

            Well, I can't really answer that since I don't know C#, so don't know what you mean by a static constructor. :( --Mike-- "There are only a limited number of jobs where they will ask to see the sausage. Most of them are in movies."  -- Christian Graus, 2/11/2002 My really out-of-date homepage Sonork - 100.10414 AcidHelm Big fan of Alyson Hannigan.

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            • N Nish Nishant

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              Ravi Bhavnani
              wrote on last edited by
              #13

              Looks like a factory pattern is what you want. /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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              • R Ravi Bhavnani

                Looks like a factory pattern is what you want. /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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                Nish Nishant
                wrote on last edited by
                #14

                [removed]

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                • N Nish Nishant

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                  Ravi Bhavnani
                  wrote on last edited by
                  #15

                  One use of a factory design pattern is to ensure that objects are properly initialized during construction. I assume this is what you'd like to accomplish via the static constructor. To implement a factory pattern for the class CFoo, do the following:

                  1. Make CFoo's constructor protected, thereby preventing anyone from doing CFoo* pFoo = new CFoo(); which could create an uninitialized instance.
                  2. Implement the static method CFoo* CFoo::Create(); that serves up a properly initialized object. The static method can set the class's static member is required.

                  You should browse thru the gang of 4 book. I think you'll enjoy it. /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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                  • N Nish Nishant

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                    Ravi Bhavnani
                    wrote on last edited by
                    #16

                    Nish [BusterBoy] wrote: Why am I re-declaring the static int You're not redeclaring it. The .h file declares it - the .cpp allocates storage for it. If you omitted it from the .cpp file you'd get an unresolved reference link error. /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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                    • N Nish Nishant

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                      Atul Dharne
                      wrote on last edited by
                      #17

                      You are not redeclaring it but you are just declaring it. As it is static it resides even if your class object has not been constructed. It is like using static variables in functions or global vars. IMO the compiler initialises them to zero if you don't do the essentials. So here just after your class def you should initialize it otherwise the compiler spews errors. Atul Sonork 100.13714 netdiva

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                      • R Ravi Bhavnani

                        Nish [BusterBoy] wrote: Why am I re-declaring the static int You're not redeclaring it. The .h file declares it - the .cpp allocates storage for it. If you omitted it from the .cpp file you'd get an unresolved reference link error. /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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                        Nish Nishant
                        wrote on last edited by
                        #18

                        Ravi Bhavnani wrote: If you omitted it from the .cpp file you'd get an unresolved reference link error. Yes I did get that error :-O :-O :-O or if you want it in Ravi-talk pinky pinky :-) Nish Nish was here, now Nish has gone; He left his soul, to turn you on; Those who knew Nish, knew him well; Those who didn't, can go to hell. I like to :jig: on the Code Project Sonork ID 100.9786 voidmain www.busterboy.org

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                        • N Nish Nishant

                          Ravi Bhavnani wrote: If you omitted it from the .cpp file you'd get an unresolved reference link error. Yes I did get that error :-O :-O :-O or if you want it in Ravi-talk pinky pinky :-) Nish Nish was here, now Nish has gone; He left his soul, to turn you on; Those who knew Nish, knew him well; Those who didn't, can go to hell. I like to :jig: on the Code Project Sonork ID 100.9786 voidmain www.busterboy.org

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                          Ravi Bhavnani
                          wrote on last edited by
                          #19

                          I think I said "picky picky". :) /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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                          • R Ravi Bhavnani

                            Looks like a factory pattern is what you want. /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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                            Navier
                            wrote on last edited by
                            #20

                            Seems to me like a Singleton pattern would do the job better. BTW the standard (well Nov96 draft at least) says a constructor can't have a static modifier (12.1 para 4) if you want official confirmation. i1.2sqrt(u).bcos(ur)sec(c) but b4.isqrt(u).ru/16

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                            • N Navier

                              Seems to me like a Singleton pattern would do the job better. BTW the standard (well Nov96 draft at least) says a constructor can't have a static modifier (12.1 para 4) if you want official confirmation. i1.2sqrt(u).bcos(ur)sec(c) but b4.isqrt(u).ru/16

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                              Ravi Bhavnani
                              wrote on last edited by
                              #21

                              I think the Singleton pattern is better suited when you want to expose methods from the one and only instance of a class. But I agree that the ClassFactory pattern can do more than serve up a single class. In fact, it's power lies in the fact that it can serve up specializations of a general base class. /ravi "There is always one more bug..." http://www.ravib.com ravib@ravib.com

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                              • N Nish Nishant

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                                Hugo Gonzalez Castro
                                wrote on last edited by
                                #22

                                Maybe this article is useful for you: Static Constructor and Destructor in C++

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