I want to share part of my code with someone so he can add some features to it
but I want to keep the core of the code secret.
The structure of my code is the following (the arrows mean #include
"header.hpp"):
________ ___________
| | | |--->|OtherPrivate1.hpp|
| |--->|Private.hpp|--->| ... |\
| | |___________|--->|OtherPrivateN.hpp| \
|main.cpp| x-->|SomeOtherPrivate.hpp|
| | __________ /
| | | |---->|OtherShared1.hpp| /
| |--->|Shared.hpp|---->| ... |/
|________| |__________|---->|OtherSharedM.hpp|
The Private.hpp contains only one template class called Private. The
Shared.hpp contains one normal class for which the definition are in
Shared.cpp. All other files can contain either one template class or one
normal class. At some point in the inclusion pattern, both part include some
privates files.
I've never created libraries, but from what I understood there is no need to
create a library for template class. Plus as my goal is to hide everything
that is private, having a library and a header file that contains the
definition is not useful.
So I think that using a library is not what I want unless there is a way to
hide the definitions of the template files.
Is there a way to share only some part of my code so the other contributors
can compile, test and run the code but don't have access to other part ?
Edit
The reason why I want to do that is because I've been developing a code for
two years and now an intern is joining me but I'm not sure that he's going to
stay and I don't want to give him everything.
ReEdit
The answers are heading toward law, licence, NDA and stuff like that... I'm
happy I learned a bit about this stuff but it was not my initial question. I
don't really have security concern but more readability and simplification. I
don't want to spent 3 months to explain my intern my whole code if he's not
staying...
I believe you should not do that. Either share the full source code, or define and document an API, and give a binary shared library implementing that documented API. If you want others to contribute to your code, give them access to all the source code.
BTW, template-s cannot really be hidden.
If you want someone else to contribute to your code, you should give access to your source code.
If you really want to hide things (IMHO it is a bad thing to do, and certainly will repeal potential contributors) you might have some plugin infrastructure.
Getting external contributions is always a hard thing. My opinion is that these days making your library free software is the only way to attract external contributors. Remember that competent developers is a scare resource, why would they contribute to your hidden thing while they have a lots of potential free software projects welcoming external contribution?
At last, a person seeing or having access to your source code does not necessarily have the right to contribute to it or to run your code (in particular, copyright laws separate the ability to read code from the legal permission to compile and run it on a computer). If your are scared of your intern, it is a legal or a social or or relational or a personal issue, not a technical one. (You probably should contact a lawyer for legal aspects and/or a therapist for relational/social/personal aspects, not ask here)
My opinion is that if you want external contributions you should publish your software with a free software license, and if you just want to have an intern (or collaborator) working on your code base you should give him access to the entire source code (you may ask a lawyer to make a written contract about mutual obligations like an NDA, but that is off-topic here). Having someone working on your code and not showing all of it is crazy, inefficient, and insulting. You are likely to ruin your reputation by behaving such way with your intern. If I was your intern, I would be pissed off and won't speak in a good way about you! Trust is even more important than contribution (but is a prerequisite).
A person having seen your source code does not any rights on it, except those defined by law, by license (e.g. a free software license) or by contract.
Details are of course specific to the legal system relevant for your case (so are off-topic here). Ask your lawyer!
NB
You are probably confusing "abstractions" (a very useful way to design software) and "information hiding" or "secrets"; there are not the same. The point is that bugs appear at the interface or the intersection of abstractions and are usually whole program (e.g. memory leaks, undefined behavior, etc...). Read more about leaky abstractions. This is why a developer should access all your source code, not some of it. The alternative would be to have a very well specified and perfectly documented API, and that is very hard to get.
I guess that it is a one person, two years project, so probably less than 150 thousand lines of source code. You probably should not spend 3 months explaining them (and if you do, it means that your software is under-designed and needs strong refactoring, which your intern would help you doing if you explain and show all of your source).
If you have template class you are pretty much unable to make these code secret. This is because of the specific of templates that allow you to create the types/methods/functions at the compiling time. When it comes to the other files. I think you have to work on using Factory software design pattern or similar.
If the law of Your country allows it You can ask Your intern to sign a contract that forbids him from disclosing or using anything than He has done or have seen during work with Your code. If He fails to keep a secret then He will need to compensate for every loss that resulted.
This costs You nothing and your intern might do a better job when he sees the whole thing.
So we have this huge (is 11000 lines huge?) mainmodule.cpp source file in our project and every time I have to touch it I cringe.
As this file is so central and large, it keeps accumulating more and more code and I can't think of a good way to make it actually start to shrink.
The file is used and actively changed in several (> 10) maintenance versions of our product and so it is really hard to refactor it. If I were to "simply" split it up, say for a start, into 3 files, then merging back changes from maintenance versions will become a nightmare. And also if you split up a file with such a long and rich history, tracking and checking old changes in the SCC history suddenly becomes a lot harder.
The file basically contains the "main class" (main internal work dispatching and coordination) of our program, so every time a feature is added, it also affects this file and every time it grows. :-(
What would you do in this situation? Any ideas on how to move new features to a separate source file without messing up the SCC workflow?
(Note on the tools: We use C++ with Visual Studio; We use AccuRev as SCC but I think the type of SCC doesn't really matter here; We use Araxis Merge to do actual comparison and merging of files)
Merging will not be such a big nightmare as it will be when you'll get 30000 LOC file in the future. So:
Stop adding more code to that file.
Split it.
If you can't just stop coding during refactoring process, you could leave this big file as is for a while at least without adding more code to it: since it contains one "main class" you could inherit from it and keep inherited class(es) with overloaded functions in several new small and well designed files.
Find some code in the file which is relatively stable (not changing fast, and doesn't vary much between branches) and could stand as an independent unit. Move this into its own file, and for that matter into its own class, in all branches. Because it's stable, this won't cause (many) "awkward" merges that have to be applied to a different file from the one they were originally made on, when you merge the change from one branch to another. Repeat.
Find some code in the file which basically only applies to a small number of branches, and could stand alone. Doesn't matter whether it's changing fast or not, because of the small number of branches. Move this into its own classes and files. Repeat.
So, we've got rid of the code that's the same everywhere, and the code that's specific to certain branches.
This leaves you with a nucleus of badly-managed code - it's needed everywhere, but it's different in every branch (and/or it changes constantly so that some branches are running behind others), and yet it's in a single file that you're unsuccessfully trying to merge between branches. Stop doing that. Branch the file permanently, perhaps by renaming it in each branch. It's not "main" any more, it's "main for configuration X". OK, so you lose the ability to apply the same change to multiple branches by merging, but this is in any case the core of code where merging doesn't work very well. If you're having to manually manage the merges anyway to deal with conflicts, then it's no loss to manually apply them independently on each branch.
I think you're wrong to say that the kind of SCC doesn't matter, because for example git's merging abilities are probably better than the merge tool you're using. So the core problem, "merging is difficult" occurs at different times for different SCCs. However, you're unlikely to be able to change SCCs, so the issue is probably irrelevant.
It sounds to me like you're facing a number of code smells here. First of all the main class appears to violate the open/closed principle. It also sounds like it is handling too many responsibilities. Due to this I would assume the code to be more brittle than it needs to be.
While I can understand your concerns regarding traceability following a refactoring, I would expect that this class is rather hard to maintain and enhance and that any changes you do make are likely to cause side effects. I would assume that the cost of these outweighs the cost of refactoring the class.
In any case, since the code smells will only get worse with time, at least at some point the cost of these will outweigh the cost of refactoring. From your description I would assume that you're past the tipping point.
Refactoring this should be done in small steps. If possible add automated tests to verify current behavior before refactoring anything. Then pick out small areas of isolated functionality and extract these as types in order to delegate the responsibility.
In any case, it sounds like a major project, so good luck :)
The only solution I have ever imagined to such problems follows. The actual gain by the described method is progressiveness of the evolutions. No revolutions here, otherwise you'll be in trouble very fast.
Insert a new cpp class above the original main class. For now, it would basically redirect all calls to the current main class, but aim at making the API of this new class as clear and succinct as possible.
Once this has been done, you get the possibility to add new functionalities in new classes.
As for existing functionalities, you have to progressively move them in new classes as they become stable enough. You will lose SCC help for this piece of code, but there is not much that can be done about that. Just pick the right timing.
I know this is not perfect, though I hope it can help, and the process must be adapted to your needs!
Additional information
Note that Git is an SCC that can follow pieces of code from one file to another. I have heard good things about it, so it could help while you are progressively moving your work.
Git is constructed around the notion of blobs which, if I understand correctly, represent pieces of code files. Move these pieces around in different files and Git will find them, even if you modify them. Apart from the video from Linus Torvalds mentioned in comments below, I have not been able to find something clear about this.
Confucius say: "first step to getting out of hole is to stop digging hole."
Let me guess: Ten clients with divergent feature sets and a sales manager that promotes "customization"? I've worked on products like that before. We had essentially the same problem.
You recognize that having an enormous file is trouble, but even more trouble is ten versions that you have to keep "current". That's multiple maintenance. SCC can make that easier, but it can't make it right.
Before you try to break the file into parts, you need to bring the ten branches back in sync with each other so that you can see and shape all the code at once. You can do this one branch at a time, testing both branches against the same main code file. To enforce the custom behavior, you can use #ifdef and friends, but it's better as much as possible to use ordinary if/else against defined constants. This way, your compiler will verify all types and most probably eliminate "dead" object code anyway. (You may want to turn off the warning about dead code, though.)
Once there's only one version of that file shared implicitly by all branches, then it's rather easier to begin traditional refactoring methods.
The #ifdefs are primarily better for sections where the affected code only makes sense in the context of other per-branch customizations. One may argue that these also present an opportunity for the same branch-merging scheme, but don't go hog-wild. One colossal project at a time, please.
In the short run, the file will appear to grow. This is OK. What you're doing is bringing things together that need to be together. Afterwards, you'll begin to see areas that are clearly the same regardless of version; these can be left alone or refactored at will. Other areas will clearly differ depending on the version. You have a number of options in this case. One method is to delegate the differences to per-version strategy objects. Another is to derive client versions from a common abstract class. But none of these transformations are possible as long as you have ten "tips" of development in different branches.
I don't know if this solves your problem, but what I guess you want to do is migrate the content of the file to smaller files independent of each other (summed up).
What I also get is that you have about 10 different versions of the software floating around and you need to support them all without messing things up.
First of all there is just no way that this is easy and will solve itself in a few minutes of brainstorming. The functions linked in your file are all vital to your application, and simply cutting them of and migrating them to other files won't save your problem.
I think you only have these options:
Don't migrate and stay with what you have. Possibly quit your job and start working on serious software with good design in addition. Extreme programming is not always the best solution if you are working on a long time project with enough funds to survive a crash or two.
Work out a layout of how you would love your file to look once it's split up. Create the necessary files and integrate them in your application. Rename the functions or overload them to take an additional parameter (maybe just a simple boolean?).
Once you have to work on your code, migrate the functions you need to work on to the new file and map the function calls of the old functions to the new functions.
You should still have your main-file this way, and still be able to see the changes that were made to it, once it comes to a specific function you know exactly when it was outsourced and so on.
Try to convince your co-workers with some good cake that workflow is overrated and that you need to rewrite some parts of the application in order to do serious business.
Exactly this problem is handled in one of the chapters of the book "Working Effectively with Legacy Code" (http://www.amazon.com/Working-Effectively-Legacy-Michael-Feathers/dp/0131177052).
I think you would be best off creating a set of command classes that map to the API points of the mainmodule.cpp.
Once they are in place, you will need to refactor the existing code base to access these API points via the command classes, once that's done, you are free to refactor each command's implementation into a new class structure.
Of course, with a single class of 11 KLOC the code in there is probably highly coupled and brittle, but creating individual command classes will help much more than any other proxy/facade strategy.
I don't envy the task, but as time goes on this problem will only get worse if it's not tackled.
Update
I'd suggest that the Command pattern is preferable to a Facade.
Maintaining/organizing a lot of different Command classes over a (relatively) monolithic Facade is preferable. Mapping a single Facade onto a 11 KLOC file will probably need to be broken up into a few different groups itself.
Why bother trying to figure out these facade groups? With the Command pattern you will be able to group and organise these small classes organically, so you have a lot more flexibility.
Of course, both options are better than the single 11 KLOC and growing, file.
One important advice: Do not mix refactoring and bugfixes. What you want is a Version of your program that is identical to the previous version, except that the source code is differently.
One way could be to start splitting up the least big function/part into it's own file and then either include with a header (thus turning main.cpp into a list of #includes, which sounds a code smell in itself *I'm not a C++ Guru though), but at least it's now split into files).
You could then try to switch all maintenance releases over to the "new" main.cpp or whatever your structure is. Again: No other changes or Bugfixes because tracking those is confusing as hell.
Another thing: As much as you may desire making one big pass at refactoring the whole thing in one go, you might bite off more than you can chew. Maybe just pick one or two "parts", get them into all the releases, then add some more value for your customer (after all, Refactoring does not add direct value so it is a cost that has to be justified) and then pick another one or two parts.
Obviously that requires some discipline in the team to actually use the split files and not just add new stuff to the main.cpp all the time, but again, trying to do one massive refactor may not be the best course of action.
Rofl, this reminds me of my old job. It seems that, before I joined, everything was inside one huge file (also C++). Then they've split it up (at completely random points using includes) into about three (still huge files). The quality of this software was, as you might expect, horrible. The project totaled at about 40k LOC. (containing almost no comments but LOTS of duplicate code)
In the end I did a complete rewrite of the project. I started by redoing the worst part of the project from scratch. Of course I had in mind a possible (small) interface between this new part and the rest. Then I did insert this part into the old project. I didn't refactor the old code to create the interface necessary, but just replaced it. Then I took made small steps from there, rewriting the old code.
I have to say that this took about half a year and there was no development of the old code base beside bugfixes during that time.
edit:
The size stayed at about 40k LOC but the new application contained many more features and presumably less bugs in its initial version than the 8 year old software. One reason of the rewrite was also that we needed the new features and introducing them inside the old code was nearly impossible.
The software was for an embedded system, a label printer.
Another point that I should add is that in theory the project was C++. But it wasn't OO at all, it could have been C. The new version was object oriented.
OK so for the most part rewriting API of production code is a bad idea as a start. Two things need to happen.
One, you need to actually have your team decide to do a code freeze on current production version of this file.
Two, you need to take this production version and create a branch that manages the builds using preprocessing directives to split up the big file. Splitting the compilation using JUST preprocessor directives (#ifdefs, #includes, #endifs) is easier than recoding the API. It's definitely easier for your SLAs and ongoing support.
Here you could simply cut out functions that relate to a particular subsystem within the class and put them in a file say mainloop_foostuff.cpp and include it in mainloop.cpp at the right location.
OR
A more time consuming but robust way would be to devise an internal dependencies structure with double-indirection in how things get included. This will allow you to split things up and still take care of co-dependencies. Note that this approach requires positional coding and therefore should be coupled with appropriate comments.
This approach would include components that get used based on which variant you are compiling.
The basic structure is that your mainclass.cpp will include a new file called MainClassComponents.cpp after a block of statements like the following:
#if VARIANT == 1
# define Uses_Component_1
# define Uses_Component_2
#elif VARIANT == 2
# define Uses_Component_1
# define Uses_Component_3
# define Uses_Component_6
...
#endif
#include "MainClassComponents.cpp"
The primary structure of the MainClassComponents.cpp file would be there to work out dependencies within the sub components like this:
#ifndef _MainClassComponents_cpp
#define _MainClassComponents_cpp
/* dependencies declarations */
#if defined(Activate_Component_1)
#define _REQUIRES_COMPONENT_1
#define _REQUIRES_COMPONENT_3 /* you also need component 3 for component 1 */
#endif
#if defined(Activate_Component_2)
#define _REQUIRES_COMPONENT_2
#define _REQUIRES_COMPONENT_15 /* you also need component 15 for this component */
#endif
/* later on in the header */
#ifdef _REQUIRES_COMPONENT_1
#include "component_1.cpp"
#endif
#ifdef _REQUIRES_COMPONENT_2
#include "component_2.cpp"
#endif
#ifdef _REQUIRES_COMPONENT_3
#include "component_3.cpp"
#endif
#endif /* _MainClassComponents_h */
And now for each component you create a component_xx.cpp file.
Of course i am using numbers but you should use something more logical based on your code.
Using preprocessor allows you to split things up without having to worry about API changes which is a nightmare in production.
Once you have production settled you can then actually work on redesign.
Well I understand your pain :) I've been in a few such projects as well and it's not pretty. There is no easy answer for this.
One approach that may work for you is to start adding safe guards in all functions, that is, checking arguments, pre/post-conditions in methods, then eventually adding unit tests all in order to capture the current functionality of the sources. Once you have this you are better equipped to re-factor the code because you will have asserts and errors popping up alerting you if you have forgotten something.
Sometimes though there are times when refactoring just may bring more pain than benefit. Then it may be better to just leave the original project and in a pseudo maintenance state and start from scratch and then incrementally adding the functionality from the beast.
You should not be concerned with reducing the file-size, but rather with reducing the class-size. It comes down to almost the same, but makes you look at the problem from a different angle (as #Brian Rasmussen suggests, your class seems to have to many responsibilities).
What you have is a classic example a known design antipattern called the blob. Take some time to read the article I point here, and maybe you may find something useful. Besides, if this project is as big as it looks, you should consider some design to prevent growing into code that you can't control.
This isn't an answer to the big problem, but a theoretical solution to a specific piece of it:
Figure out where you want to split the big file into subfiles. Put comments in some special format at each of those points.
Write a fairly trivial script that will break the file apart into subfiles at those points. (Perhaps the special comments have embedded filenames that the script can use as instructions for how to split it.) It should preserve the comments as part of the splitting.
Run the script. Delete the original file.
When you need to merge from a branch, first recreate the big file by concatenating the pieces back together, do the merge, and then re-split it.
Also, if you want to preserve the SCC file history, I expect the best way to do that is to tell your source control system that the individual piece files are copies of the original. Then it will preserve the history of the sections that were kept in that file, although of course it will also record that large parts were "deleted".
One way to split it without too much danger would be to take a historic look at all the line changes. Are there certain functions that are more stable than others? Hot spots of change if you will.
If a line hasn't been changed in a few years you can probably move it to another file without too much worry. I'd take a look at the source annotated with the last revision that touched a given line and see if there are any functions you could pull out.
Wow, sounds great. I think explaining to your boss, that you need a lot of time to refactor the beast is worth a try. If he doesn't agree, quitting is an option.
Anyway, what I suggest is basically throwing out all the implementation and regrouping it into new modules, let's call those "global services". The "main module" would only forward to those services and ANY new code you write will use them instead of the "main module". This should be feasible in a reasonable amount of time (because it's mostly copy and paste), you don't break existing code and you can do it one maintenance version at a time. And if you still have any time left, you can spend it refactoring all old depending modules to also use the global services.
Do not ever touch this file and the code again!
Treat is like something you are stuck with. Start writing adapters for the functionality encoded there.
Write new code in different units and talk only to adapters which encapsulate the functionality of the monster.
... if only one of the above is not possible, quit the job and get you a new one.
My sympathies - in my previous job I encountered a similar situation with a file that was several times larger than the one you have to deal with. Solution was:
Write code to exhaustively test the function in the program in question. Sounds like you won't already have this in hand...
Identify some code that can be abstracted out into a helper/utilities class. Need not be big, just something that is not truly part of your 'main' class.
Refactor the code identified in 2. into a separate class.
Rerun your tests to ensure nothing got broken.
When you have time, goto 2. and repeat as required to make the code manageable.
The classes you build in step 3. iterations will likely grow to absorb more code that is appropriate to their newly-clear function.
I could also add:
0: buy Michael Feathers' book on working with legacy code
Unfortunately this type of work is all too common, but my experience is that there is great value in being able to make working but horrid code incrementally less horrid while keeping it working.
Consider ways to rewrite the entire application in a more sensible way. Maybe rewrite a small section of it as a prototype to see if your idea is feasible.
If you've identified a workable solution, refactor the application accordingly.
If all attempts to produce a more rational architecture fail, then at least you know the solution is probably in redefining the program's functionality.
My 0.05 eurocents:
Re-design the whole mess, split it into subsystems taking into account the technical and business requirements (=many parallel maintenance tracks with potentially different codebase for each, there is obviously a need for high modifiability, etc.).
When splitting into subsystems, analyze the places which have most changed and separate those from the unchanging parts. This should show you the trouble-spots. Separate the most changing parts to their own modules (e.g. dll) in such a way that the module API can be kept intact and you don't need to break BC all the time. This way you can deploy different versions of the module for different maintenance branches, if needed, while having the core unchanged.
The redesign will likely need to be a separate project, trying to do it to a moving target will not work.
As for the source code history, my opinion: forget it for the new code. But keep the history somewhere so you can check it, if needed. I bet you won't need it that much after the beginning.
You most likely need to get management buy-in for this project. You can argue perhaps with faster development time, less bugs, easier maintaining and less overall chaos. Something along the lines of "Proactively enable the future-proofness and maintenance viability of our critical software assets" :)
This is how I'd start to tackle the problem at least.
Start by adding comments to it. With reference to where functions are called and if you can move things around. This can get things moving. You really need to assess how brittle the code base it. Then move common bits of functionality together. Small changes at a time.
Another book you may find interesting/helpful is Refactoring.
Something I find useful to do (and I'm doing it now although not at the scale you face), is to extract methods as classes (method object refactoring). The methods that differ across your different versions will become different classes which can be injected into a common base to provide the different behaviour you need.
I found this sentence to be the most interesting part of your post:
> The file is used and actively changed in several (> 10) maintenance versions of our product and so it is really hard to refactor it
First, I would recommend that you use a source control system for developing these 10 + maintenance versions that supports branching.
Second, I would create ten branches (one for each of your maintenance versions).
I can feel you cringing already! But either your source control isn't working for your situation because of a lack of features, or it's not being used correctly.
Now to the branch you work on - refactor it as you see fit, safe in the knowledge that you'll not upset the other nine branches of your product.
I would be a bit concerned that you have so much in your main() function.
In any projects I write, I would use main() only perform initialization of core objects - like a simulation or application object - these classes is where the real work should go on.
I would also initialize an application logging object in main for use globally throughout the program.
Finally, in main I also add leak detection code in preprocessor blocks that ensure it's only enabled in DEBUG builds. This is all I would add to main(). Main() should be short!
You say that
> The file basically contains the "main class" (main internal work dispatching and coordination) of our program
It sounds like these two tasks could be split into two separate objects - a co-ordinator and a work dispatcher.
When you split these up, you may mess up your "SCC workflow", but it sounds like adhering stringently to your SCC workflow is causing software maintenance problems. Ditch it, now and don't look back, because as soon as you fix it, you'll begin to sleep easy.
If you're not able to make the decision, fight tooth and nail with your manager for it - your application needs to be refactored - and badly by the sounds of it! Don't take no for an answer!
As you've described it, the main issue is diffing pre-split vs post-split, merging in bug fixes etc.. Tool around it. It won't take that long to hardcode a script in Perl, Ruby, etc. to rip out most of the noise from diffing pre-split against a concatenation of post-split. Do whatever's easiest in terms of handling noise:
remove certain lines pre/during concatenation (e.g. include guards)
remove other stuff from the diff output if necessary
You could even make it so whenever there's a checkin, the concatenation runs and you've got something prepared to diff against the single-file versions.
"The file basically contains the "main class" (main internal work dispatching and coordination) of our program, so every time a feature is added, it also affects this file and every time it grows."
If that big SWITCH (which I think there is) becomes the main maintenance problem, you could refactor it to use dictionary and the Command pattern and remove all switch logic from the existing code to the loader, which populates that map, i.e.:
// declaration
std::map<ID, ICommand*> dispatchTable;
...
// populating using some loader
dispatchTable[id] = concreteCommand;
...
// using
dispatchTable[id]->Execute();
I think the easiest way to track the history of source when splitting a file would be something like this:
Make copies of the original source code, using whatever history-preserving copy commands your SCM system provides. You'll probably need to submit at this point, but there's no need yet to tell your build system about the new files, so that should be ok.
Delete code from these copies. That should not break the history for the lines you keep.
I think what I would do in this situation is bit the bullet and:
Figure out how I wanted to split the file up (based on the current development version)
Put an administrative lock on the file ("Nobody touch mainmodule.cpp after 5pm Friday!!!"
Spend your long weekend applying that change to the >10 maintenance versions (from oldest to newest), up to and including the current version.
Delete mainmodule.cpp from all supported versions of the software. It's a new Age - there is no more mainmodule.cpp.
Convince Management that you shouldn't be supporting more than one maintenance version of the software (at least without a big $$$ support contract). If each of your customers have their own unique version.... yeeeeeshhhh. I'd be adding compiler directives rather than trying to maintain 10+ forks.
Tracking old changes to the file is simply solved by your first check-in comment saying something like "split from mainmodule.cpp". If you need to go back to something recent, most people will remember the change, if it's 2 year from now, the comment will tell them where to look. Of course, how valuable will it be to go back more than 2 years to look at who changed the code and why?
If you've got a codebase which is a bit messy in respect to coding standards - a mix of different conventions from different people - is it reasonable to give one person the task of going through every file and bringing it up to meet standards?
As well as being tremendously dull, you're going to get a mass of changes in SVN (or whatever) which can make comparing versions harder. Is it sensible to set someone on the whole codebase, or is it considered stupid to touch a file only to make it meet standards? Should files be left alone until some 'real' change is needed, and then updated?
Tagged as C++ since I think different languages have different automated tools for this.
Should files be left alone until some 'real' change is needed, and then updated?
This is what I would do.
Even if it's primarily text layout changes, doing it by a manual process on a large scale risks breaking code that was working.
Treat it as a refactor and do it locally whenever code has to be touched for some other reason. Add tests if they're missing to improve your chances of not breaking the code.
If your code is already well covered by tests, you might get away with something global, but I still wouldn't advocate it.
I also think this is pretty much language-agnostic.
It also depends on what kind of changes you are planning to make in order to bring it up to your coding standard. Everyone's definition of coding standard is different.
More specifically:
Can your proposed changes be made to the project with 100% guarantee that the entire project will work identically the same as before? For example, changes that only affect comments, line breaks and whitespaces should be fine.
If you do not have 100% guarantee, then there is a risk that should not be taken unless it can be balanced with a benefit. For example, is there a need to gain a deeper understanding of the current code base in order to continue its development, or fix its bugs? Is the jumble of coding conventions preventing these initiatives? If so, evaluate the costs and benefits and decide whether a makeover is justified.
If you need to understand the current code base, here is a technique: tracing.
Make a copy of the code base. Note that tracing involves adding code, so it should not be performed on the production copy.
In the new copy, insert many fprintf (trace) statements into any functions considered critical. It may be possible to automate this.
Run the project with various inputs and collect those tracing results. This will help everyone understand the current project's design.
Another technique for understanding the current code base is to document the dependencies in the project.
Some kinds of dependencies (interface dependency, C++ include dependency, C++ typedef / identifier dependency) can be extracted by automated tools.
Run-time dependency can only be extracted through tracing, or by profiling tools.
I was thinking it's a task you might give a work-experience kid or put out onto RentaCoder
This depends mainly on the codebase's size.
I've seen three trainees given the task to go through a 2MLoC codebase (several thousand source files) in order to insert one new line into the standard disclaimer at the top of all the source files (with the line's content depending on the file's name and path). It took them several days. One of the three used most of that time to write a script that would do it and later only fixed the files where the script had failed to insert the line correctly, the other two just ploughed through the files. (The one who wrote the script later got a job at that company.)
The job of manually adapting all those files in that codebase to certain coding standards would probably have to be measured in man-years.
OTOH, if it's just a few dozen files, it's certainly doable.
Your codebase is very likely somewhere in between, so your best bet might be to set a "work-experience kid" to find out whether there's a tool that can do this to your satisfaction and, if so, make it work.
Should files be left alone until some 'real' change is needed, and then updated?
I'd strongly advice against this. If you do this, you will have "real" changes intermingled with whatever reformatting took place, making it nigh impossible to see the "real" changes in the diff.
You can address the formatting aspect of coding style fairly easily. There are a number of tools that can auto-format your code. I recommend hooking one of these up to your version control tool's "check in" feature. This way, people can use whatever format they want while editing their code, but when it gets checked in, it's reformatted to the official style.
In general, I think it's best if you can do the big change all at once. In the past, we've done the following:
1. have a time dedicated to the reformatting when most people aren't working (e.g. at night or on the weekend
2. have a person check out as many files as possible at that time, reformat them, and check them in again
With a reformatting-only revision, you don't have to figure out what has changed in addition to the formatting.
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I'm working on a fairly big open source RTS game engine (Spring). I recently added a bunch of new C++ functions callable by Lua, and am wondering how to best document them, and at the same time also stimulate people to write/update documentation for a lot of existing Lua call-outs.
So I figured it may be nice if I could write the documentation initially as doxygen comments near the C++ functions - this is easy because the function body obviously defines exactly what the function does. However, I would like the documentation to be improved by game developers using the engine, who generally have little understanding of git (the VCS we use) or C++.
Hence, it would be ideal if there was a way to automatically generate apidocs from the C++ file, but also to have a wiki-like web interface to allow a much wider audience to update the comments, add examples, etc.
So I'm wondering, does there exist a web tool which integrates doxygen style formatting, wiki-like editing for those comments (preferably without allowing editing any other parts of the source file) and git? (to commit the comments changed through the web interface to a special branch)
We developers could then merge this branch every now and then to add the improvements to the master branch, and at the same time any improvements by developers to the documentation would end up on this web tool with just a merge of the master branch into this special branch.
I haven't found anything yet, doubt something this specific exists yet, so any suggestions are welcome!
This is a very cool idea indeed, and a couple of years ago I also had a very strong need for something like that. Unfortunately, at least back then, I wasn't able to find something like that. Doing a quick search on sourceforge and freshmeat also doesn't bring up anything related today.
But I agree that such a wiki frontend to user-contributed documentation would be very useful, I know for a fact that something like this was recently being discussed also within the Lua community (see this).
So, maybe we can determine the requirements in order to come up with a basic working draft/prototype?
Hopefully, this would get us going to initiate such a project with a minimum set of features and then simply release it into the wild as an open source project (e.g. on sourceforge), so that other users can contribute to it.
Ideally, one could use unified patches to apply changes that were contributed in such a fashion. Also, it would probably make sense to restrict modifications only to adding/editing comments, instead of allowing arbitrary modifications of text, this could probably be implemented by using a simple regex.
Maybe, one could implement something like that by modifying an existing (established) wiki software such as mediawiki. Or preferably something that's already using git as a backend for storage purposes. Then, one would mainly need to cater for those Doxygen-style comments, and provide a simple interface on top of it.
Thinking about it some more, DoxyGen itself already provides support for generating HTML documentation, so from that perspective it might actually be interesting to see, how DoxyGen could possibly be extended, so that it is well integrated with such a scripted backend that allows for easy customization of embedded source code documentation.
This would probably mainly boil down to providing a standalone script with doxygen (e.g. in python, php or perl) and then optionally embed forms in the automatically created HTML documentation, so that documentation fixes/augmentations can be sent to the corresponding script via a browser, which in turn would write any modifications back to a corresponding branch.
In the long term, it would be cool if such a script would support different types of backends (CVS, SVN or git), or at least be implemented generically enough, so that it is easily extendible.
So, if we can come up with a good design, it might even be possible that such a modification would be generally accepted as a contribution to doxygen itself, which would also give the whole thing much more exposure and momentum.
Even if the idea doesn't directly materialize into a real project, it would be interesting to see how many other users actually like the idea, so that it could possibly be mentioned in the doxygen issue tracker (https://github.com/doxygen/doxygen/issues/new).
EDIT: You may also want to check out this article titled "Documentation, Git and MediaWiki".
Last term (August - December 2008) me and some class mates wrote an application in C++. Nothing spectacular, it is an ORM for Sqlite3. We implemented some stuff like reflection to make it work and release the end user from the ugly stuff. Personally, i think we made a nice job, and that our ORM could actually be useful for someone (even though its writen specifically for Sqlite3, its easily adaptable for oter databases).
Consequently, i`ve come to the conclusion that it should be published somewhere (sourceforge most likely) as an open source project. But, as it was a term project, there are some things that need to be addresesed before doing that. Namely, it has some memory leaks that should be fixed, and some parts of the code could be refactored to make everyone´s life easier in the future.
I would like to know more experienced C++ programmers opinion on some issues:
Is it worth rewriting some parts to
apply new techonologies (for example,
boost).
Should our ORM be adapted to latest
C++ standard? Is there any benefit in
doing this?
How will we know when our code is
ready for release?
What are the chances that this ORM
will be forgotten into the mists of
the internet? (i.e is it worth
publishing it beyond personal pride
as a programmer?)
Right now i can`t think of many more questions, but i would like to read on similar experiences.
EDIT: I should probably translate my code + comments to english right? (self question)
Thanks in advance.
I guess I am "more experienced" with regard to your particular question. I co-developed an open source web application language & template system a lot like ColdFusion back in the early days of web design before Java or ASP were around. You can still see it at http://www.steelblue.com/ if you are interested. It's still used at the company I was at when it was developed, but I don't think anywhere else.
What I found is that unless you are already well connected and people are watching what you are doing, getting people to use your open source code is just about as hard as selling somone your closed source program. You really need to advocate for your project and it should have some kind of unique selling proposition that distinguishes it from the compitition.
So, that's the unsolicited advice. Here are some specific answers to the questions you had...all purely my opinion, of course.
I wouldn't rewrite any code unless you have a featuer you want to put in. That feature might be compatibility with a specific platforms or compilers. It might be to support a new db datatype or smarter indicies or whatever. If you are going to put some more serious work into the applicaiton, think about a roadmap of what you can realistically accomplish in the next iteration and what choices will make the app the "most better" at the end of your cycle.
Release the code as soon as it is usable for a specific purpose, any purpose. Two reasons. First off, there might be someone who wants it for that purpose right now. If it's not available, they will use something else. Also, if it's open source, they might contribute back to the project. Second, the sooner you find out how much people want to use the code, the better. Either it will be more popular than you expect and you can get excited about continuing the development....or....you will find that no one is even visiting your web page to see what you've got. In either case, better to know sooner than later what people really want from your project so you can take that into account when planning new releases.
About the "forgotten into the mists." I think most projects are. I don't want to be a downer, but looking at Wikipedia, there were 5 C++ ORM tools popular enough to get mention and they were all open source. As I said above, unless you can sell your idea to people, they are going to go with another proven open source solution. For someone to choose you over them, three things have to happen: 1. They need a feature you have that the others don't. 2. They find your project web site and it demonstrates the superiority of your code. 3. They trust your code enough to give it a shot.
On the other hand, if you are in this for the long haul and want to continue development thigns get easier over time. Eventually the project will get all the basics covered and you can start developing those new featuers that aren't in the other solutions. Also, the longer you are in active development the more trustworthy the project will seem. Finally, you will get more experience in the nitch. 2 years from now you will be better positioned to say where your effort will have the most impact on bettering the project.
A final thought: If you are enjoying it, learning from it, and it's not getting in the way of you keeping food on the table, it's a good use of your time.
Good luck!
-Al
Regarding the open source part:
If you really want to make it an open source project, you really should publish it regardless of it's current state - fully working and debugged - or half working and full of memory leaks.
Just, if it's state is bad, make sure to document it, and give it a suitable version number (less than one?). then others may view your code, suggest improving, join your team, etc...
My--rather random--thoughts on the matter (in the order I think is most important):
How will we know when our code is ready for release?
Like Liran Orevi said: if you're going open source release early. Document it reasonable well, and take the time to provide a road map of planned or hoped for future improvements (these are a invitation for people to help you, so note which ones have no one working on them).
Is it worth rewriting some parts to apply new technologies (for example, boost).
Should our ORM be adapted to latest C++ standard? Is there any benefit in doing this?
SQLite relies on a fairly limited base. Maybe you don't want your tool to demand a much heavier environment. If the code in not currently a tangled and unmaintainable mess, you might want to avoid boost and newest frills. Once you have a stable release (1.0 at least) you can starting thinking about the improvements that can be made for version 2.
What are the chances that this ORM will be forgotten into the mists of the internet? (i.e is it worth publishing it beyond personal pride as a programmer?)
Most things end up in the big /dev/null in the sky, and there is only one way to find out... If it goes anywhere at all, you win. If it doesn't it was a modest investment, and maybe you learned something while you were at it.