How to split strings across multiple lines in CMake?

Question

I usually have a policy in my project, to never create lines in text files that exceed a line length of 80, so they are easily editable in all kinds of editors (you know the

Answer 1

CMake 3.0 and newer

Use the string(CONCAT) command:

set(MYPROJ_VERSION_MAJOR "1")
set(MYPROJ_VERSION_MINOR "0")
set(MYPROJ_VERSION_PATCH "0")
set(MYPROJ_VERSION_EXTRA "rc1")
string(CONCAT MYPROJ_VERSION "${MYPROJ_VERSION_MAJOR}"
                             ".${MYPROJ_VERSION_MINOR}"
                             ".${MYPROJ_VERSION_PATCH}"
                             "-${MYPROJ_VERSION_EXTRA}")

Although CMake 3.0 and newer support line continuation of quoted arguments, you cannot indent the second or subsequent lines without getting the indentation whitespace included in your string.

CMake 2.8 and older

You can use a list. Each element of the list can be put on a new line:

set(MYPROJ_VERSION_MAJOR "1")
set(MYPROJ_VERSION_MINOR "0")
set(MYPROJ_VERSION_PATCH "0")
set(MYPROJ_VERSION_EXTRA "rc1")
set(MYPROJ_VERSION_LIST "${MYPROJ_VERSION_MAJOR}"
                        ".${MYPROJ_VERSION_MINOR}"
                        ".${MYPROJ_VERSION_PATCH}"
                        "-${MYPROJ_VERSION_EXTRA}")

A list used without quotes is concatenated without white-space:

message(STATUS "Version: " ${MYPROJ_VERSION_LIST})
-- Version: 1.0.0-rc1

If you really need a string, you can convert the list to a string first:

string(REPLACE ";" "" MYPROJ_VERSION "${MYPROJ_VERSION_LIST}")
message(STATUS "Version: ${MYPROJ_VERSION}")
-- Version: 1.0.0-rc1

Any semicolons in your original strings will be seen as list element separators, and removed. They must be escaped:

set(MY_LIST "Hello World "
            "with a \;semicolon")