It allows us to have functions with a similar structure as the functions given by CMake standard, so that we will have a consistent way to use all functions across our projects. Using the function cmake_parse_arguments makes the management of parameters for Cmake function easier. Since we check if that this keyword is defined and the number of parameters given to it, it makes it mandatory for people calling this function to pass this keyword to the function, and to make it have less than 3 arguments associated. Since we don’t check if it is defined in the function, this means that it is not mandatory, but the string "Bad name" is consider a wrong argument when associated with this keyword.įinally, the keyword ARRAY_OF_PARAM is used to pass several arguments to the function. The keyword NAME is used to pass only one argument to the function. This means that, if it is passed to the function, then, the variable MY_FUNCTION_IS_ACTIVATED will be set to TRUE, else it will be set to FALSE.
#Cmake function code
The keyword IS_ACTIVATED is actually a flag that can be omit and can be used to trigger some code in the function or modify its behavior, for example. Let’s dive in ! In this sample of code, we create a function which can be called like that : my_function(NAME "John Doe" ARRAY_OF_PARAM "First param" "Second Param" IS_ACTIVATED). Moreover, it even allow us to handle an infinity of parameters even more easily 😉 Indeed, they have given us the ability to add keywords in our functions parameters so that we could group them by type, and check their validity more easily. To face function with a big number of parameters and with different "kinds" of parameters, the CMake developers have created a new feature very interesting. Moreover, since the CMake functions tends to have a lot of parameters, it can become a lot of pain to check all of them that way.
I have also added some other variables, ARGN and ARGV, so that you can have some knowledge about them, if you want to be able to manipulate or to extract more informations about the parameters passed to your own Cmake functions 😉.Įven if this function is simple to explain, it requires you to write a lot of code to each check each parameter, and to make sure that they are all what you function expects. Indeed, with the variable ARGC, we are able to see the number of arguments and we can control it by using some conditions, for example. With the previous sample of code, we will be able to display some very interesting informations about the numbers of arguments. This first solution consists of using a CMake variable available to us giving us the number of arguments used when the function is called.Įnter fullscreen mode Exit fullscreen mode To make sure that your function has the right number of arguments when called, we have two solutions (two that I am aware of 😆). Indeed, you can call a function, declared as taking only one arguments, with three arguments without having CMake preventing you.Įven if this behavior is wanted by CMake developers and allows some nice features, if you don’t know about it, it can be the origin of a lot of bugs and unwanted behaviors in your CMake scripts. Unlike in other languages, the number of arguments when calling a CMake function is actually not checked by the system. In CMake, like in many other languages, it is possible to create and use functions.
Self promotion: You can find other articles on my website 😉
#Cmake function how to
I’m Xavier Jouvenot and in this small post, we are going to see how to correctly create a CMake function with proper arguments.
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