Question

The following is my CMakeLists file. By default, I expect it to define the symbol ALLEGRO_STATICLINK in the agui_allegro5 library, but it does not, however when I check off WANT_SHARED it defines it, which it shouldnt, but does not define AGUI_BACKEND_BUILD as it should. Is my logic flawed or something?

cmake_minimum_required(VERSION 2.6)

project(agui)

OPTION(WANT_SHARED "Build agui and the backend as a shared library" OFF) 

OPTION(WANT_ALLEGRO5_BACKEND "Build the Allegro 5 backend" ON) 

set(AGUI_SOURCES
    src/Agui/ActionEvent.cpp
    src/Agui/ActionListener.cpp
    src/Agui/BaseTypes.cpp
    src/Agui/BlinkingEvent.cpp
    src/Agui/BorderLayout.cpp
    src/Agui/Color.cpp
    src/Agui/Dimension.cpp
    src/Agui/EmptyWidget.cpp
    src/Agui/EventArgs.cpp
    src/Agui/FlowLayout.cpp
    src/Agui/FocusListener.cpp
    src/Agui/FocusManager.cpp
    src/Agui/Font.cpp
    src/Agui/FontLoader.cpp
    src/Agui/Graphics.cpp
    src/Agui/GridLayout.cpp
    src/Agui/Gui.cpp
    src/Agui/Image.cpp
    src/Agui/ImageLoader.cpp
    src/Agui/Input.cpp
    src/Agui/KeyboardListener.cpp
    src/Agui/Layout.cpp
    src/Agui/MouseListener.cpp
    src/Agui/Point.cpp
    src/Agui/Rectangle.cpp
    src/Agui/ResizableText.cpp
    src/Agui/ResizableBorderLayout.cpp
    src/Agui/SelectionListener.cpp
    src/Agui/TopContainer.cpp
    src/Agui/Widget.cpp
    src/Agui/WidgetListener.cpp
    src/Agui/Widgets/Button/Button.cpp
    src/Agui/Widgets/Button/ButtonListener.cpp
    src/Agui/Widgets/CheckBox/CheckBox.cpp
    src/Agui/Widgets/CheckBox/CheckBoxListener.cpp
    src/Agui/Widgets/DropDown/DropDown.cpp
    src/Agui/Widgets/DropDown/DropDownListener.cpp
    src/Agui/Widgets/Frame/Frame.cpp
    src/Agui/Widgets/Frame/FrameListener.cpp
    src/Agui/Widgets/Label/Label.cpp
    src/Agui/Widgets/Label/LabelListener.cpp
    src/Agui/Widgets/ListBox/ListBox.cpp
    src/Agui/Widgets/ListBox/ListBoxListener.cpp
    src/Agui/Widgets/RadioButton/RadioButton.cpp
    src/Agui/Widgets/RadioButton/RadioButtonListener.cpp
    src/Agui/Widgets/RadioButton/RadioButtonGroup.cpp
    src/Agui/Widgets/ScrollBar/HScrollBar.cpp
    src/Agui/Widgets/ScrollBar/HScrollBarListener.cpp
    src/Agui/Widgets/ScrollBar/VScrollBar.cpp
    src/Agui/Widgets/ScrollBar/VScrollBarListener.cpp
    src/Agui/Widgets/ScrollPane/ScrollPane.cpp
    src/Agui/Widgets/Slider/Slider.cpp
    src/Agui/Widgets/Slider/SliderListener.cpp
    src/Agui/Widgets/Tab/Tab.cpp
    src/Agui/Widgets/Tab/TabbedPane.cpp
    src/Agui/Widgets/Tab/TabbedPaneListener.cpp
    src/Agui/Widgets/TextBox/TextBox.cpp
    src/Agui/Widgets/TextBox/TextBoxListener.cpp
    src/Agui/Widgets/TextBox/ExtendedTextBox.cpp
    src/Agui/Widgets/TextField/TextField.cpp
    src/Agui/Widgets/TextField/TextFieldListener.cpp
    )

set(ALLEGRO5_BACKEND_SOURCES
    src/Agui/Backends/Allegro5/Allegro5Font.cpp
    src/Agui/Backends/Allegro5/Allegro5FontLoader.cpp
    src/Agui/Backends/Allegro5/Allegro5Graphics.cpp
    src/Agui/Backends/Allegro5/Allegro5Image.cpp
    src/Agui/Backends/Allegro5/Allegro5ImageLoader.cpp
    src/Agui/Backends/Allegro5/Allegro5Input.cpp
    )

    include_directories (./include) 
if(WANT_SHARED)
  add_library(agui SHARED ${AGUI_SOURCES})
  set_target_properties(agui PROPERTIES DEFINE_SYMBOL "AGUI_BUILD")

  if(WANT_ALLEGRO5_BACKEND)
    add_library(agui_allegro5 SHARED ${ALLEGRO5_BACKEND_SOURCES})
    set_target_properties(agui_allegro5 PROPERTIES DEFINE_SYMBOL "AGUI_BACKEND_BUILD")
    target_link_libraries (agui_allegro5 agui)
  endif()

else()
  add_library(agui STATIC ${AGUI_SOURCES})

  if(WANT_ALLEGRO5_BACKEND)
    add_library(agui_allegro5 STATIC ${ALLEGRO5_BACKEND_SOURCES})
    set_target_properties(agui_allegro5 PROPERTIES DEFINE_SYMBOL "ALLEGRO_STATICLINK")
  endif()

endif()

Thanks

Answer 1

According to CMake documentation “DEFINE_SYMBOL sets the name of the preprocessor symbol defined when compiling sources in a shared library” while you are trying to use it on a static library, hence no effect. You may also find this discussion useful.