Libraries, And Dependencies

Libraries And Executables

Source

05-static-libraries/
├── CMakeLists.txt
├── hello.c
├── hello-first.c
├── hello.h
├── hello-name.c
├── hello-name.h
└── hello-second.c

• 05-static-libraries/CMakeLists.txt

• 05-static-libraries/hello.h

• 05-static-libraries/hello.c

• 05-static-libraries/hello-name.c

• 05-static-libraries/hello-name.h

• 05-static-libraries/hello-first.c

• 05-static-libraries/hello-second.c

• Raw toolchain in action: Object Code Archives/Static Libraries

• Defining a library

  05-static-libraries/CMakeLists.txt

  ADD_LIBRARY(hello                             # <--- target "hello"
    hello.h hello.c
    hello-name.h hello-name.c)
  

  Note

  Header files are not compiled, but adding them is convenient for IDE usage.

• Executables only contain main code (all code that depends on is in the library)

  05-static-libraries/CMakeLists.txt

  ADD_EXECUTABLE(hello-first hello-first.c)     # <--- target "hello-first"
  ADD_EXECUTABLE(hello-second hello-second.c hello.c hello-name.c)
  

$ cmake  ~/work/jfasch-home/trainings/material/soup/cmake/05-static-libraries/
...
$ make
[ 57%] Linking C executable hello-first
/usr/bin/ld: CMakeFiles/hello-first.dir/hello-first.c.o: in function `main':
hello-first.c:(.text+0x10): undefined reference to `hello'
/usr/bin/ld: hello-first.c:(.text+0x29): undefined reference to `hello_name'
collect2: error: ld returned 1 exit status

⟶ Dependencies!

Targets And Dependencies

• Executables depend on libraries

• ⟶ dependencies

• hello-first depends on hello

• hello-second depends on hello

05-static-libraries/CMakeLists.txt

TARGET_LINK_LIBRARIES(hello-first hello)      # <--- "hello-first" depends on "hello"
TARGET_LINK_LIBRARIES(hello-second hello)     # <--- "hello-second" depends on "hello"

• Executables may depend on libraries

• Libraries may depend on libraries

• (Nothing ever depends on an executable)

• ⟶ Directed Acyclic Graph (DAG)

Visualizing Dependencies

• Project sanity: knowing your dependencies

• ⟶ Graphviz package

Generating dot files

$ pwd
/tmp/build
$ cmake --graphviz=Demo.dot ~/work/jfasch-home/trainings/material/soup/cmake/05-static-libraries/
$ ls -l *.dot*
-rw-r--r--. 1 jfasch jfasch 1260 Jul 13 19:31 Demo.dot
-rw-r--r--. 1 jfasch jfasch  336 Jul 13 19:31 Demo.dot.hello.dependers
-rw-r--r--. 1 jfasch jfasch  222 Jul 13 19:31 Demo.dot.hello-first
-rw-r--r--. 1 jfasch jfasch  225 Jul 13 19:31 Demo.dot.hello-second

Convert into viewable image

$ dot -Tpng Demo.dot > Demo.png