In my place we have a big C++ code base and I think there's a problem how header files are used.
There're many Visual Studio project, but the problem is in concept and is not related to VS. Each project is a module, performing particular functionality. Each project/module is compiled to library or binary. Each project has a directory containing all source files - *.cpp and *.h. Some header files are API of the module (I mean the to the subset of header files declaring API of the created library), some are internal to it.
Now to the problem - when module A needs to work with module B, than A adds B's source directory to include search path. Therefore all B's module internal headers are seen by A at compilation time.
As a side effect, developer is not forced to concentrate what is the exact API of each module, which I consider a bad habit anyway.
I consider an options how it should be on the first place. I thought about creating in
each project a dedicated directory containing interface header files only. A client module wishing to use the module is permitted to include the interface directory only.
Is this approach ok? How the problem is solved in your place?
UPD On my previous place, the development was done on Linux with g++/gmake and we indeed used to install API header files to a common directory is some of answers propose. Now we have Windows (Visual Studio)/Linux (g++) project using cmake to generate project files. How I force the prebuild install of API header files in Visual Studio?
Thanks
Dmitry
It sounds like your on the right track. Many third party libraries do this same sort of thing. For example:
3rdParty/myLib/src/ -contains the headers and source files needed to compile the library
3rdParty/myLib/include/myLib/ - contains the headers needed for external applications to include
Some people/projects just put the headers to be included by external apps in /3rdParty/myLib/include, but adding the additional myLib directory can help to avoid name collisions.
Assuming your using the structure: 3rdParty/myLib/include/myLib/
In Makefile of external app:
---------------
INCLUDE =-I$(3RD_PARTY_PATH)/myLib/include
INCLUDE+=-I$(3RD_PARTY_PATH)/myLib2/include
...
...
In Source/Headers of the external app
#include "myLib/base.h"
#include "myLib/object.h"
#include "myLib2/base.h"
Wouldn't it be more intuitive to put the interface headers in the root of the project, and make a subfolder (call it 'internal' or 'helper' or something like that) for the non-API headers?
Where I work we have a delivery folder structure created at build time. Header files that define libraries are copied out to a include folder. We use custom build scripts that let the developer denote which header files should be exported.
Our build is then rooted at a substed drive this allows us to use absolute paths for include directories.
We also have a network based reference build that allows us to use a mapped drive for include and lib references.
UPDATE: Our reference build is a network share on our build server. We use a reference build script that sets up the build environment and maps(using net use) the named share on the build server(i.e. \BLD_SRV\REFERENCE_BUILD_SHARE). Then during a weekly build(or manually) we set the share(using net share) to point to the new build.
Our projects then a list of absolute paths for include and lib references.
For example:
subst'ed local build drive j:\
mapped drive to reference build: p:\
path to headers: root:\build\headers
path to libs: root:\build\release\lib
include path in project settings j:\build\headers; p:\build\headers
lib path in project settings j:\build\release\lib;p:\build\release\lib
This will take you local changes first, then if you have not made any local changes(or at least you haven't built them) it will use the headers and libs from you last build on the build server.
I've seen problems like this addressed by having a set of headers in module B that get copied over to the release directory along with the lib as part of the build process. Module A then only sees those headers and never has access to the internals of B. Usually I've only seen this in a large project that was released publicly.
For internal projects it just doesn't happen. What usually happens is that when they are small it doesn't matter. And when they grow up it's so messy to separate it out no one wants to do it.
Typically I just see an include directory that all the interface headers get piled into. It certainly makes it easy to include headers. People still have to think about which modules they're taking dependencies on when they specify the modules for the linker.
That said, I kinda like your approach better. You could even avoid adding these directories to the include path, so that people can tell what modules a source file depends on just by the relative paths in the #includes at the top.
Depending on how your project is laid out, this can be problematic when including them from headers, though, since the relative path to a header is from the .cpp file, not from the .h file, so the .h file doesn't necessarily know where its .cpp files are.
If your projects have a flat hierarchy, however, this will work. Say you have
base\foo\foo.cpp
base\bar\bar.cpp
base\baz\baz.cpp
base\baz\inc\baz.h
Now any header file can include
#include "..\baz\inc\baz.h
and it will work since all the cpp files are one level deeper than base.
In a group I had been working, everything public was kept in a module-specific folder, while private stuff (private header, cpp file etc.) were kept in an _imp folder within this:
base\foo\foo.h
base\foo\_imp\foo_private.h
base\foo\_imp\foo.cpp
This way you could just grab around within your projects folder structure and get the header you want. You could grep for #include directives containing _imp and have a good look at them. You could also grab the whole folder, copy it somewhere, and delete all _imp sub folders, knowing you'd have everything ready to release an API.
Within projects headers where usually included as
#include "foo/foo.h"
However, if the project had to use some API, then API headers would be copied/installed by the API's build wherever they were supposed to go on that platform by the build system and then be installed as system headers:
#include <foo/foo.h>
Related
I decided to make a header file(s) that includes all the relatively simple methods I frequently use,to simply include said file into any project I'm working on instead of having to copy methods from one project to the other every-time I need them,I'm also going to be updating this file(s) as I go,now,I know there are multiple ways to go about including said file,either by adding it's file path to the #include directive itself,something like:
#include"C:\\Projects\\MyProgram\\Files\\MyHeader.h"
Or by adding the folder containing the header file(s) to the Additional Include Directories in the project's properties,which is what I'm currently doing,and it's working just fine.
However,I'm a bit worried about the fact the header file is not included INSIDE the project folder,so in the event I had to switch computers or wipe my hard drive,I'd have to make sure that this header file(s) is placed in the same exact file path,otherwise all of the projects that include it will simply fall apart...
And it goes without saying,I'm not making a copy of the header file to place in each project folder,for obvious reasons.
So I'd like to know if there anyway around this?
How about the ability to set an Additional Include Directory for ALL of my projects,so in the event of a wipe,a new PC or simply the old directory becoming inconvenient,all I have to do is set a new directory and all of my projects will start referring to that one?
If not,is my only choice is to build the header file(s) into a custom library? Because I know absolutely nothing about that,and I'd appreciate if someone would direct me to where I can learn to do that.
Thanks in advance.
You must use relative path. Do this:
1- Create a new subfolder in your solution. Let's call it include:
2- Put your shared headers in this subfolder. Example : myCommonFunctions.h
First solution: Use relative include path (see ../ at begining)
#include "../include/myCommonFunctions.h"
Second solution: Use relative path in Addtional include directories (see ../ at begining)
Now, you can write :
#include "myCommonFunctions.h"
By doing this, you don't depend from an absolute path C:\\Projects\\MyProgram\\... and You will no longer need to copy files manually if you change computers
I'm trying to make a cross-platforms crypto library in C++ at https://github.com/haithngn/cryptor something like https://github.com/MailCore/mailcore2
The Structure is:
Can I make any header files can be include in the statements like this:
#include <Cryptor/MD5Encryptor.h>
I can include these header directly from absolutely file path
../core/CryptorCore.h
But these format will make the source code cannot build succeed in an XCode Project.
I tried to simulate the MailCore2 but that's very difficult.
Hope you can suggest me any solution or do a favor PR on my Repository.
Thanks,
You need to have a proper hierarchy. First, no, you can't have
#include <Cryptor/MD5Encryptor.h>
with your current setup, not while building the library, and not without flattening the hierarchy when installing your files (which CMake can do).
What you can do is:
#include <Cryptor/core/abstract/MD5Encryptor.h>
if you add your project inside a Cryptor folder instead of being at the root of your project.
I would advise you to create a Cryptor.cmake file that would allow people to pick up your library once installed, so that they don't have to know where the library includes are or what the libraries name is.
It should not be necessary to point to every single header file. Just add all directories containing these header files with include_directories(PATH_TO_HEADERS).
For the include of the header file src/core/CryptorCore.h with
#include "CryptorCore.h"
you have to point to
include_directories(${PROJECT_DIR}/core/)
I am developing a product with a team using CMake. We have several Visual Studio projects (libraries and executables) inside of our CMake project which reference other project headers (via target_include_directories()). In a source file these header includes look like:
#include "some_header.h" // from project_x
#include "another_header.h" // from project_y
I'd like to be able to include these headers with paths that reference the project they are pulled from, e.g.:
#include "project_x/some_header.h"
#include "project_y/another_header.h"
What is the most acceptable way to do this? I have thought of a couple solutions:
Add the directory which contains the project as an include path. This has the undesirable side-effect of including everything and seems like a bad solution.
Include a subfolder of the project called 'include' which contains a folder named with the same as the project, which creates a slightly redundant path: /<project_name>/include/<project_name>/<...>
There is a third solution, to use a shared include directory with a subfolder for each project, but it will not work for our project because we group our build projects by category in the file system and Visual Studio solution and it will cause the folder structure inside of /include/ to diverge from the rest of source tree which is undesirable.
Are there any better (or more canonical/idiomatic) ways to accomplish this?
If you have a project structure like this:
project_x/some_header.h
project_y/another_header.h
and you want to keep all of your CMakeLists the same, then I would introduce another folder in each project:
project_x/project_x/some_header.h
project_y/project_y/another_header.h
Of course, this requires changing the includes in each project to reflect this new structure, including the project where the header is defined proper.
There's some precedence to this, as this is how curl and googletest do it.
Edit: I understand this is very similar to the second approach you outlined. If your directory structure already employs include directories, then my suggestion is exactly the same as your second one. At the very least, this should confirm your intuition that this isn't an entirely absurd thing to do, even if it creates some redundancy.
I am having a problem of getting compile errors (red underlines) like:
Error: cannot open source file "stdafx.h"
Here an edited screenshot of the environment:
On the LEFT is my Visual Studio Solution Directory list with the "Show All Files" off.
I am working on a school project, and each Folder are the source files of different parts of the project with different people who are in-charge of them.
For example, Student A and B are incharge of AST and PARSER folders (we will call them sub-projects).
We have an API for each sub-project so other sub-projects know what to call.
At the TOP-CENTER, we have my Source File for a class QueryProcessor. (just the first few lines)
Below it, is the Output for the Build Success.
The red lines are all over all the classes, mainly cause the #include "stdafx.h" cannot be opened by the environment.
On the RIGHT, that is the stdafx.h where we include all the different sub-projects so we save the trouble of each project having a different stdafx.h
However, I am able to build the project. I am pretty sure I am doing this directory/linking wrongly.
This should work
Right click on the solution file
Click Open in Windows Explorer
Find file stdfx.h in explorer and copy the path of the folder
In visual studio solution explorer, Right click on the project file
Click properties-> C/C++ -> General
In the Additional Include Directories paste the path
Combining folders and virtual folders in VC is from my point of view messy because the virtual folders indicate that all files are in one directory and the folders created on the harddrive obviously indicate that all files are in different directories. You can combine it if you know what's going on but in your case I would not recommend it.
I assume you missunderstand the purpose of stdafx.h The purpose of this header file is NOT to put all header filles into it and then just include it to all other files. Here is a SO question about this Purpose of stdafx.h
After cleaning up your stdafx.h file include as many header files into your .cpp files and only put these includes in your header files if they are required in the header file
Turn on show all files, now you will work with actual folders and you can be sure that if you adress a folder like "PKB" that this folder really exists since you can see it in the left solution explorer.
If you use using namespace std; for example make sure you also include the required header files. You might think "hey I already included e.g. iostream in another header file which I now include in this header file so I don't need it" That will really destroy you when you work with bigger projects.
Oh and regarding the stdafx.h include problem as soon as you switch to show all files I assume you will realise that stdafx is in a different file than the file where you use the include. Maybe something like #include "..\stdafx.h" is required (depending on your structure).
I think it's obivious but if you include a header file the include is allway relative to the file which is including the other header file.
stdafx.h is commonly used for creating a precompiled-header, which essentially is a compile-time optimisation such that the compiler will not continually compile these headers for every compilation unit.
If any of these headers changes, you will need to do a full system rebuild.
In reality it is preferable only to use it to include standard headers plus third-party headers (like boost libraries and similar) that you are not ever going to change.
You may decide that some of your own libraries are "set in stone" and can also be included.
Every project, i.e. every part of the project that is built into a separate unit (DLL or .exe) should have its own precompiled header and its own version of stdafx.h
Projects should only ever include their own .stdafx and not those of other projects, therefore this header file can also be used to define your dllexport macro.
When arranging your project headers you should be aware of:
1. Which headers are included externally
2. Which headers are only included internally, and are not even included indirectly externally.
The latter sort should include your stdafx.h file and should ideally not be in the same directory as those headers included from outside your project.
In a large C++ solution, is there a best/standard way to separate the include files necessary to build an intermediary DLL and the include files which will be used by the DLL clients ?
We have grouped all the include files in a folder called Interface (for DLL interface), but there the customers have to either include the Interface folder as a default include folder or type the full name as:
#include "ProjectName/Interface/myinterface.h"
Wouldn't it be better to create a separate folder called exports where I would create a folder called ProjectName and put the include files there ? So that the customers would be typing:
#include "ProjectName/myinterface.h"
If I do the thing right above, then should I keep the files within the solution and produce a post build event (I use Visual Studio 2k5) to copy the files into the "export" folder (/ProjectName/) ? Or is it better to just include directly the files from this folder within my project (this is more direct and has less chances to cause maintenance issues ?
I am more looking for advice than for a definite solution.
Thank you for reading this !
Anthony
If an interface could consist of more than one header,
#include "ProjectName/Interface/header1.h"
seems better to me.