Cmake Set Variable Example

A lot of variables used by cmake are set with the project and enable language calls.

Cmake set variable example. So it could get important to set some variables before those commands are used. For msvc projects the variables are those that are set in a developer command prompt for a specific platform. Multiple arguments will be joined as a semicolon separated list to form the actual variable value to be set. It s typically used to define a common set of functions or macros in the calling script.

When we faced the same issue you have a toolkit which produces a script so set the compile environment we changed the toolkit in a way that it produces a toolchain file along with the script. Example set my variable the value is a string by default a local variable is only defined in the current directory and any subdirectories added through the add subdirectory command. Set var true set var main cpp set var1 var2 but cmake does also know global cached variables persisted in cmakecache txt and if normal and cached variables of the same name exist in the current scope normal variables do hide the cached ones. It s a lot like the include directive in c c.

Running cmake will produce a cmakecache txt file that is the cmake configuration. Mostly you will use normal variables. For example the msvc x64 x64 environment is the same as running the developer command prompt for vs 2017 or. If you want to set a variable from the command line cmake offers a variable cache.

Placeholder expect zero or more arguments. Set my cache variable value cache string description this will not replace an existing value. Signatures of this command that specify a value. Similar to the set command the list command creates new variable values in the current scope even if the list itself is actually defined in a parent scope.

Cmake variables are defined at file scope. The list subcommands append insert filter prepend pop back pop front remove at remove item remove duplicates reverse and sort may create new values for the list within the current cmake variable scope. See the cmake language 7 variables documentation for the scopes and interaction of normal variables and cache entries. The syntax for declaring a variable and setting it if it is not already set is.

The include command executes another cmake script in the same scope as the calling script. An environment encapsulates the environment variables that are set in the process that visual studio uses to invoke cmake exe. Some variables are already here like cmake build type. Within that text file there are two variables needed to build a simpleitk program simpleitk dir and itk dir simpleitk dir needs to be set to the directory that contains the file simpleitkconfig cmake and itk dir needs to be the directory containing the file itkconfig cmake.

It uses the variable cmake module path as a search path. To extend the scope of a variable there are two possibilities.