I have the following simple c++ project structure:
include/ contains header files
src/ contains the source files
cli/ contains source files with a main method
Currently, I build the whole source into a single static library and then compile each file in cli/ individually and link that static library. I do this with just one CMakeLists.txt in the root directory that basically looks like this:
include_directories(include)
set(HEADERS
include/file1.hpp
include/file2.hpp
include/sub1/file3.hpp
include/sub2/file4.hpp
)
set(SOURCE_FILES
src/file1.cpp
src/file2.cpp
src/sub1/file3.cpp
src/sub2/file4.cpp
)
set(EXECUTABLE_FILES
cli/app1.cpp
cli/app2.cpp
cli/app3.cpp
)
add_library(code STATIC ${SOURCE_FILES} ${HEADERS})
foreach (file ${EXECUTABLE_FILES})
get_filename_component(executable ${file} NAME_WE)
add_executable(${executable} ${file})
target_link_libraries(${executable} code)
endforeach ()
When I add a new file, I just add it to the appropriate list of files (headers, source, or executable).
Advantage: Simple work-flow with little overhead for maintaining the CMakeLists.txt.
Disadvantage: For each executable, the one big library is linked, even if the executable only uses the stuff in one of the source files (right now, there are about 15 executables using different subsets of the 25 source files).
My Question: Can I fix the disadvantage while keeping the advantage?
The only solution for fixing the disadvantage I could find is to manually specify for each executable which source files it needs. This is too tedious and error prone for my use case, as I will certainly forget to update the dependencies.
This is a bit unsatisfactory, as there is a very simple rule to which sources need to be linked: Every source file has a corresponding header file and I need to link src/file.cpp if and only if include/file.hpp is included. Is there any good way to tell CMake about this rule? Or do I need to write my own script that generates the CMakeLists.txt (which feels a bit like writing my own build system, which I would like to avoid)?
Related
Suppose my source code has the following directory structure:
C:\USERS\PC\SOURCE\REPOS\my_app_src
├───apps {a.hh, b.cc, c.hh, d.cc}
│ └───biosimulations {main1.hh, main1.cc, x.hh, y.cc}
└───core {w.cc, x.hh, y.hh, z.cc}
└───algorithms {p.hh, p.cc, q.hh, r.cc, s.hh, s.cc}
└───trees {r.hh, r.cc, main2.hh, main2.cc}
Each folder has any number of header and source files with any name.
How can I write a CMakeList.txt file for this project?
This is scientific software.
I need to be able to use various parts of the same library to compile and build executables for multiple applications.
For example, in the above sample, main1.exe and main2.exe are supposed to be two different executable files.
Sometimes, I need to be able to switch off one or another executable from compiling.
Do you want the project to support testing, installation, and/or packaging?
No, I don't need them. I just need to be able to compile and execute the apps.
What is in core?
Model classes. e.g., Atom, Protein, Chain, etc.
Are the source files for core part of a single library or executable?
Part of executable. There is no static or dynamic library in the project.
Using add_subdirectory and add_library commands, recursively add all of the source files in the directory structure.
cmake_minimum_required(VERSION 3.x)
project(my_app)
# Add subdirectories recursively
add_subdirectory(apps)
add_subdirectory(core)
add_subdirectory(simulations)
add_subdirectory(ui)
add_subdirectory(utils)
# Create the final executable
add_executable(my_app main.cpp)
# Link the libraries to the executable
target_link_libraries(my_app core simulations apps ui utils)
Then in each subdirectories(apps,core,simulations,ui, utils) you would need to add a new CMakeLists.txt that tells which source files are in that directory and create a library.
cmake_minimum_required(VERSION 3.x)
SET(SRC_FILES
program.cpp
)
#for static libraries
add_library(core STATIC ${SRC_FILES})
#for dynamically linking libraries
add_library(core SHARED ${SRC_FILES})
# If you need executable here
# add_executable(core ${SRC_FILES})
This needs to be repeated for all subdirectories, untill all sources are covered. Above examples gives general structure, you need to define CMAKE flags as required.
Currently, I need help either creating a CMakeList.txt, or simply figuring out the cmake command for the following.
I have some source files in the same directory, called A.cpp, B.cpp, C.cpp, D.cpp. I need to compile these such that the executables are named as A, B, C, D, respectively.
I want to use CMake to automatically traverse the directory and generate the corresponding executable file instead of adding the corresponding executable file in CMakeList.txt every time I add a file.
This is a bit of an odd request. Usually I'd suggest manually writing add_executable where needed since it's more maintainable.
In CMake, there isn't really a good way to collect all files in a directory. You can use file(GLOB ...) to grab all files; but this gets done at configure time, and if you introduce new sources then CMake won't detect the new source and won't reconfigure automatically or build the new sources without explicitly being told to reconfigure.
If you're able to discretely list each source, it would be better. But otherwise what you are requesting can be done with a combination of a foreach through each source file using get_filename_component to get the file name and passing it to add_executable
set(source_files src/a.cpp src/b.cpp src/c.cpp ...)
# Loop through each source file
foreach(source_file IN LISTS source_files)
# Get the name of the file without the extension (e.g. 'a' from src/a.cpp'
get_filename_component(target_name ${source_file} NAME_WE)
# Create an executable with the above name, building the above source
add_executable("${target_name}" "${source_file}"
endforeach()
If discretely listing the source files isn't possible, you can use file(GLOB...) or file(GLOB_RECURSE):
file(GLOB source_files "src/*.cpp")
But again; this prevents automatically detecting when new sources get added, and I don't recommend it.
I am using Cmake to compile a static version of the library from source.
The source code has a structure that looks like this:
src/
module1/
x.cpp
x.h
...
module2/
y.cpp
y.h
...
and so on...
Compiling a static version of the library is not difficult. However for distribution purposes, I just want to distribute the the headers (x.h, y.h, ...) and static libraries (module1.a, module2.a, ...).
Is there some command in GCC or CMAKE to automatically collect all of the headers and put them into a separate folder?
I am aware that I could manually separate the source and headers, or I could simply distribute all of the code (source and headers), but that is wasteful and undesireable for my particular use case. Alternatively, I could write a pretty simple Python script to do it, but it seems to me that this is probably a pretty common scenario. So I would guess that there is something in Gcc or Cmake to do it.
Note: I am not in charge of maintaining the codebase, so I have no say in how the project is structured. If I was, I could have separated the code into src and include folders.
The best thing to do is have cmake glob and install all your artifacts.
# append to your existing CMakeLists.txt
install(TARGETS module1 module2 #adjust to use your names
ARCHIVE DESTINATION lib)
file(GLOB_RECURSE header_list "*.h") #adjust if necessary
install(FILES ${header_list}
DESTINATION include)
Be aware that globbing isn't perfect, and the file list is only updated when cmake is run (i.e., it won't detect added or removed files on its own).
As a follow up to this question:
Add Source in a subdirectory to a cmake project
What is the best way (perhaps using the FILE directive?) to select all the .cpp and .h files in the subdirectory and add them to the SOURCE variable defined in the parent directory?
Example from answer to question above:
set(SOURCE
${SOURCE}
${CMAKE_CURRENT_SOURCE_DIR}/file1.cpp
${CMAKE_CURRENT_SOURCE_DIR}/file2.cpp
PARENT_SCOPE
)
set(HEADERS
${HEADERS}
${CMAKE_CURRENT_SOURCE_DIR}/file1.hpp
${CMAKE_CURRENT_SOURCE_DIR}/file2.hpp
PARENT_SCOPE
)
Is it possible to do something like this?
FILE(GLOB SUB_SOURCES *.cpp)
set(SOURCE
${SOURCE}
${CMAKE_CURRENT_SOURCE_DIR}/${SUB_SOURCES}
PARENT_SCOPE
)
What is the best way (using CMake) to compile all the sources in a directory and a subdirectory into a single output file (not multiple libraries?)
I think what you are looking for is the aux_source_directory command.
aux_source_directory Find all source files in a directory.
aux_source_directory( )
Collects the names of all the source files in the specified directory
and stores the list in the provided. This command is
intended to be used by projects that use explicit template
instantiation. Template instantiation files can be stored in a
"Templates" subdirectory and collected automatically using this
command to avoid manually listing all instantiations.
It is tempting to use this command to avoid writing the list of source
files for a library or executable target. While this seems to work,
there is no way for CMake to generate a build system that knows when a
new source file has been added. Normally the generated build system
knows when it needs to rerun CMake because the CMakeLists.txt file is
modified to add a new source. When the source is just added to the
directory without modifying this file, one would have to manually
rerun CMake to generate a build system incorporating the new file.
Your CMakeLists.txt within the subdirectory could look like this:
aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR} SUB_SOURCES)
set(SOURCE
${SOURCE}
${SUB_SOURCES}
PARENT_SCOPE
)
The recommended practice is however, as you see from the documentation, to list the files individually within CMakeLists.txt as changes to the CMakeLists.txt file triggers running cmake.
I hope this was helpful and to the point.
I have a C++ project where I've used directories as more of an organizational element -- the way one might use packages in Java or directories in PHP. Directories are not intended to be self-sufficient elements, but rather just a way of organizing the whole of the project and keeping me from being overwhelmed by sources. How can I construct my CMakeLists.txt files to deal with this? Making the directories libraries doesn't seem to fit here, since they are all interdependent and not intended to be used that way.
As a related issue, most of the examples I've seen of multiple subdirectories in CMake (and there aren't very many of those) have ignored or glossed over the issue of setting include_directories, which is something I've been having trouble with. Short of combing my source files to determine which file depends on which and in what directory, is there anyway to just set all directories under /src/ as potential include directories and let CMake work out which ones are actually dependent?
Here's an example structure:
--src
--top1
--mid1
--bot1
--src1.cpp
--hdr1.h
--bot2
--src2.cpp
--hdr2.h
--mid2
--bot3
--src3.cpp
--src4.cpp
--hdr3.h
--top2
--mid3
--src5.cpp
--hdr4.h
So on and so forth. How can I structure my CMakeLists.txt files to handle this sort of structure?
Since the directory structure in your project is just there to keep your files organized, one approach is to have a CMakeLists.txt that automatically finds all sources files in the src directory and also adds all directories as include directories that have a header file in them. The following CMake file may serve as a starting point:
cmake_minimum_required(VERSION 3.12)
project (Foo)
file (GLOB_RECURSE Foo_SOURCES CONFIGURE_DEPENDS "src/*.cpp")
file (GLOB_RECURSE Foo_HEADERS CONFIGURE_DEPENDS "src/*.h")
set (Foo_INCLUDE_DIRS "")
foreach (_headerFile ${Foo_HEADERS})
get_filename_component(_dir ${_headerFile} PATH)
list (APPEND Foo_INCLUDE_DIRS ${_dir})
endforeach()
list (REMOVE_DUPLICATES Foo_INCLUDE_DIRS)
add_executable(FooExe ${Foo_SOURCES})
target_include_directories(FooExe PRIVATE ${Foo_INCLUDE_DIRS})
The two file(GLOB_RECURSE ... commands determine the set of source and header files. The foreach loop computes the set of include directories from the list of all header files. The CONFIGURE_DEPENDS flags tells CMake to re-run the glob command at build time.
One drawback with computing the set of source files is that CMake will not automatically detect when new files are added to your source tree. You manually have to re-create your build files then.
Though #sakra gave a good answer to this question, I believe it is more proper to approach it more in depth.
We want to separate our code into modules and libraries for many reasons. Like code encapsulation, re usability, easier debugging etc. This idea would propagate in compiling process too.
In other word, we want to divide the compilation process into little compilation steps, each belong to one module. So every module must have its own compilation procedure. This is why we use one CMakeLists.txt file per directory. Hence every directory would have its own compilation commands and there would be one master CMakeLists.txt file in the root directory of your project.
Here is an example. Consider the following structure of a project:
src/
|
- main.cpp
|
_sum/
|
- sum.h
|
- sum.cpp
We would have one CmakeLists.txt Per directory. First directory is the root directory of the project which src/ folder is in it. here is content for that file:
cmake_minimum_required(VERSION 3.4)
project(multi_file)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_FLAGS "-Wall")
add_subdirectory(src)
Next CMakeLists.txt would located in src/ directory:
add_subdirectory("sum")
add_executable(out main.cpp)
target_link_libraries(out sum)
And the last one will be in the sum/ directory:
add_library(sum SHARED sum.cpp)
I hope this helps. I created a github repository in case you feel you need to see the code or you need further explanation.
I'm not an expert on CMake but since there are no other answers I'll take a look at the documentaton and give it a go. Organizing source and include files in different directories is pretty much the norm.
It looks like CMake allows you to give a list of include directories:
http://www.cmake.org/cmake/help/cmake-2-8-docs.html#command:include_directories
So something like:
include_directories("src/top1/mid1/bot1" "src/top1/mid1/bot2/" ... )
These are passed to the compiler so it can find the header files and will be passed for each of the source files. So any of your source files should be able to include any of the header files (which I think is what you're asking for).
Similar to that you should be able to list all your source files in the add_executable command:
add_executable(name "src/top1/mid1/bot1/src1.cpp" "src/top1/id1/bot2/src2.cpp" ...)
So this would be a naive way of getting everything to build. Each source file will be compiled and will look for headers in all those directories and then the object files will get linked together. Consider if there is any way of simplifying this such that you don't need so many include folders, maybe there are only a few common header files that need to be referenced by all source files. If things get more complex you can buiild sub-hierarchies into libraries etc. Also consider seperating source files and headers (e.g. in src and include).