Building libraries...

This is a discussion on Building libraries... within the C++ Programming forums, part of the General Programming Boards category; When working in C it was common for me to build libraries of useful functions. Generally, to facilitate smart linking ...

  1. #1
    Banned
    Join Date
    Aug 2010
    Location
    Ontario Canada
    Posts
    9,547

    Building libraries...

    When working in C it was common for me to build libraries of useful functions. Generally, to facilitate smart linking each function would be in it's own source page producing a granularity of one function per object.

    Am I correct in assuming the minimum object size in C++ is 1 class, in that each class can be in it's own object but that all methods of that class have to be in the same object... so the granularity, within the larger library, is 1 class per object, not one method per object?

  2. #2
    Password:
    Join Date
    Dec 2009
    Location
    NC
    Posts
    587
    A small test confirms that it is possible to separate methods into separate objects.

    main.cpp
    Code:
    #include <iostream>
    
    #include "test.h"
    
    using namespace std;
    
    int main(int argc, char** argv)
    {
    	test t;
    	cout << t.method1() << " " << t.method2() << endl;
    }
    test.h
    Code:
    class test
    {
    	public:
    	int method1();
    	int method2();
    };
    test1.cpp
    Code:
    #include "test.h"
    
    int test::method1()
    {
    	return 1;
    }
    test2.cpp
    Code:
    #include "test.h"
    
    int test::method2()
    {
    	return 2;
    }
    Code:
    $ g++ -c main.cpp
    $ g++ -c test1.cpp
    $ g++ -c test2.cpp
    $ g++ main.o test1.o test2.o
    $ ./a.out
    1 2
    Notice that the last invocation of g++ is just a wrapper for the linker(ld), it links the separate objects into a single executable.

  3. #3
    Banned
    Join Date
    Aug 2010
    Location
    Ontario Canada
    Posts
    9,547
    Ok... thanks for that.

  4. #4
    Registered User Codeplug's Avatar
    Join Date
    Mar 2003
    Posts
    4,662
    Modern linkers can remove unused symbols without putting them in their own translation units. I've never seen C++ code that followed that old-school method.

    Focus more on maintainability, readability, and usability when splitting up your source files.

    gg

  5. #5
    Password:
    Join Date
    Dec 2009
    Location
    NC
    Posts
    587
    Quote Originally Posted by CommonTater View Post
    Ok... thanks for that.
    I know it seems odd to waste enough time to do all that, but that was a thought provoking question.

  6. #6
    Banned
    Join Date
    Aug 2010
    Location
    Ontario Canada
    Posts
    9,547
    Quote Originally Posted by User Name: View Post
    I know it seems odd to waste enough time to do all that, but that was a thought provoking question.
    Your efforts and those of others have been an enormous help to me in all this.... and you gotta know I appreciate it. Sometimes the people on this forum are flat out amazing....

  7. #7
    Banned
    Join Date
    Aug 2010
    Location
    Ontario Canada
    Posts
    9,547
    Quote Originally Posted by Codeplug View Post
    Modern linkers can remove unused symbols without putting them in their own translation units. I've never seen C++ code that followed that old-school method.

    Focus more on maintainability, readability, and usability when splitting up your source files.

    gg
    As in... work in chapters, not pages... one class, one header, one source... which of course makes good sense. But once again I find myself not wanting to make noobish mistakes I will regret in 6 months.

    Back in my C days -- LOL, all of 3 days ago! -- I would archive the most useful stuff in one of several .lib files I've built up... one for windows, one for console, one for, well, whaterer. These have gotten fairly large over time and I've often found myself weeding through them getting rid of stuff I'll most likely never need again; you know kind of like that box in the basement...

    Imagine my surprise when, in C++ this is not only encouraged, it's by design! Whoda thunk it?

    However it strikes me that C++ works in bigger blobs than C or Pascal, groups of methods rather than single functions leaving me with my question....

    Thanks guys!

  8. #8
    -bleh-
    Join Date
    Aug 2010
    Location
    somewhere in this universe
    Posts
    452
    You could use namespace to organize your classes.
    "All that we see or seem
    Is but a dream within a dream." - Poe

  9. #9
    Banned
    Join Date
    Aug 2010
    Location
    Ontario Canada
    Posts
    9,547
    Quote Originally Posted by nimitzhunter View Post
    You may want to use namespace to organize your classes.
    I gave that some thought and at some point I figure that will become a helpful tool, although at this moment I have no idea how I'd do that... I mean, I think I get the syntax now, but on the more practical level...

    Ok right now I have a "todo" list of about 15 projects all loosely related to my current online offering... You know, enhancements, accessories... new weapons for the washing machine, kind of stuff. I can see several ways of going with namespaces...

    1) Create namespaces by functions... FileStuff, AudioStuff, VideoStuff, etc.
    2) Create a unique namespace for each library file. (Which I organize loosely like #1 anyway)
    3) Create my own "signature" namespace that I use for everything.
    4) different Namespace for each class.

    After your suggestion, I'm kinda leaning on #2 ...

  10. #10
    Password:
    Join Date
    Dec 2009
    Location
    NC
    Posts
    587
    I think #3 would be the easiest. Just decide on a name for your library, and make everything inside a namespace named after the name of your library. #2 is pretty similar to #3, so consider this my option of both of them.

    #1 would be my favorite, but instead of by function, organize by purpose. It would also entail a crap load more work...

    #4 is pretty much pointless, because it would end up having the same effect as populating the global namespace with a lot of classes, except then it would be populated with a lot of namespaces.

  11. #11
    Banned
    Join Date
    Aug 2010
    Location
    Ontario Canada
    Posts
    9,547
    Quote Originally Posted by User Name: View Post
    I think #3 would be the easiest. Just decide on a name for your library, and make everything inside a namespace named after the name of your library. #2 is pretty similar to #3, so consider this my option of both of them.

    #1 would be my favorite, but instead of by function, organize by purpose. It would also entail a crap load more work...

    #4 is pretty much pointless, because it would end up having the same effect as populating the global namespace with a lot of classes, except then it would be populated with a lot of namespaces.
    Hmmm... given that I'm likely to end up with several library files with multiple classes (etc) in each... sorted by by some, hopefully sensible, criterion. I'm kinda thinking the 2nd option makes best sense to me... namespace per .lib file.... but #3 does appeal to my vanity

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. run time error while loading shared libraries
    By mijax in forum C++ Programming
    Replies: 7
    Last Post: 05-16-2010, 07:27 AM
  2. Replies: 7
    Last Post: 05-13-2008, 03:47 AM
  3. building boost libraries
    By l2u in forum C++ Programming
    Replies: 3
    Last Post: 05-09-2007, 08:34 AM
  4. Building with libraries
    By Opel_Corsa in forum C++ Programming
    Replies: 5
    Last Post: 01-22-2007, 09:50 PM
  5. MinGW thread-safe runtime libraries
    By Mario F. in forum C++ Programming
    Replies: 3
    Last Post: 08-21-2006, 08:15 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21