Automatically add all files in a folder to a target using CMake

Question

I am considering switching a cross platform project from separate build management systems in Visual C    XCode and makefiles to CMake   One essential feature I need is to add automatically all files in a directory to a target  While this is easy to do with make  it is not easily doable with Visual C   and XCode  correct me if I am wrong   Is it possible to do it in directly in CMake  How

User · Answer

So Why not use powershell to create the list of source files for you. Take a look at this script

param (
    [Parameter(Mandatory=$True)]
    [string]$root 
)

if (-not (Test-Path  -Path $root)) {    
throw "Error directory does not exist"
}

#get the full path of the root
$rootDir = get-item -Path $root
$fp=$rootDir.FullName;


$files = Get-ChildItem -Path $root -Recurse -File | 
         Where-Object { ".cpp",".cxx",".cc",".h" -contains $_.Extension} | 
         Foreach {$_.FullName.replace("${fp}\","").replace("\","/")}

$CMakeExpr = "set(SOURCES "

foreach($file in $files){

    $CMakeExpr+= """$file"" " ;
}
$CMakeExpr+=")"
return $CMakeExpr;

Suppose you have a folder with this structure

C:\Workspace\A
--a.cpp
C:\Workspace\B 
--b.cpp

Now save this file as "generateSourceList.ps1" for example, and run the script as

~>./generateSourceList.ps1 -root "C:\Workspace" > out.txt

out.txt file will contain

set(SOURCE "A/a.cpp" "B/b.cpp")

User · Answer

As of CMake 3 1  the developers strongly discourage users from using file GLOB or file GLOB RECURSE to collect lists of source files   Note  We do not recommend using GLOB to collect a list of source files from your source tree  If no CMakeLists txt file changes when a source is added or removed then the generated build system cannot know when to ask CMake to regenerate  The CONFIGURE DEPENDS flag may not work reliably on all generators  or if a new generator is added in the future that cannot support it  projects using it will be stuck  Even if CONFIGURE DEPENDS works reliably  there is still a cost to perform the check on every rebuild   See the documentation here  There are two goods answers   1    2   here on SO detailing the reasons to manually list source files   It is possible  E g  with file GLOB  cmake minimum required VERSION 2 8   file GLOB helloworld SRC       quot   h quot        quot   cpp quot     add executable helloworld   helloworld SRC    Note that this requires manual re-running of cmake if a source file is added or removed  since the generated build system does not know when to ask CMake to regenerate  and doing it at every build would increase the build time  As of CMake 3 12  you can pass the CONFIGURE DEPENDS flag to file GLOB to automatically check and reset the file lists any time the build is invoked  You would write  cmake minimum required VERSION 3 12   file GLOB helloworld SRC CONFIGURE DEPENDS  quot   h quot   quot   cpp quot    This at least lets you avoid manually re-running CMake every time a file is added

User · Answer

The answer by Kleist certainly works  but there is an important caveat    When you write a Makefile manually  you might generate a SRCS variable using a function to select all  cpp and  h files  If a source file is later added  re-running make will include it    However  CMake  with a command like file GLOB       will explicitly generate a file list and place it in the auto-generated Makefile  If you have a new source file  you will need to re-generate the Makefile by re-running cmake   edit  No need to remove the Makefile

User · Answer

Extension for  Kleist answer   Since CMake 3 12 additional option CONFIGURE DEPENDS is supported by commands file GLOB  and file GLOB RECURSE   With this option there is no needs to manually re-run CMake after addition deletion of a source file in the directory - CMake will be re-run automatically on next building the project   However  the option CONFIGURE DEPENDS implies that corresponding directory will be re-checked every time building is requested  so build process would consume more time than without CONFIGURE DEPENDS   Even with CONFIGURE DEPENDS option available CMake documentation still does not recommend using file GLOB  or file GLOB RECURSE  for collect the sources

[c++] Automatically add all files in a folder to a target using CMake?

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