Variables in Project.meta
=========================
bake allows you to use

- user defined
- predefined
- environment

variables in your Project.meta file (in this priority). If a variable is not found, it will be evaluated to an empty string.

Using variables
***************

Variables can be used using the following syntax:

.. code-block:: console

   $(ABC)

The variable ABC will be substituted by its value, therefore a real life usage would look
something like this:

.. code-block:: console

   IncludeDir "$(ABC)"

User defined variables
**********************

There are two ways to create user defined variables.

#. The variable is defined with the `--set` command line option:

.. code-block:: console

    User@Host:~$ bake ... --set MyVar="Hello world!"

#. THe variable is defined directly in the Project.meta file.

.. code-block:: console

    Set MyVar, value: "Hello world!"
    Set MyVar, cmd: "ruby calcVar.rb"

In the latter one the variable is set to the output of the command.

Predefined bake environment variables
*************************************

========================================    ===============================================     ========================================
Variable                                    Description                                         Example
========================================    ===============================================     ========================================
*$(MainConfigName)*                         Evaluates to the main config name                   Debug

*$(MainProjectName)*                        Evaluates to the main project name                  bootloader

*$(ConfigName)*                             Evaluates to the config name                        lib

*$(ProjectName)*                            Evaluates to the project name                       canDriver

*$(ProjectDir)*                             Evaluates to the full path of the project           C:/Root/MyProject
                                            directory

*$(MainProjectDir)*                         Evaluates to the full path of the root projec       C:/Root/Main
                                            directory

*$(OutputDir)*                              Evaluates to the full path of the output            build/lib_bootloader_Debug
                                            directory of the current config

*$(OutputDir,projName,confName)*            Evaluates to the output dir of a specific           build/lib_some_Debug
                                            config

*$(ArtifactName)*                           Evaluates to the artifact.                          bootloader_1.0.elf

*$(ArtifactNameBase)*                       Evaluates to the base artifact name                 bootloader_1.0
                                            (Without file exension)

*$(Time)*                                   Evaluates to the current time                       2012-12-24 20:00:00 +0200

*$(Hostname)*                               Evaluates to the hostname                           MY_COMPUTER

*$(CPPPath)*                                Evaluates to the base path of the                   /usr/bin
                                            c++ compiler

*$(CPath)*                                  Evaluates to the base path of the                   /usr/bin
                                            c compiler

*$(ASMPath)*                                Evaluates to the base path of the                   /usr/bin
                                            assembler

*$(ArchiverPath)*                           Evaluates to the base path of the                   /usr/bin
                                            archiver

*$(LinkerPath)*                             Evaluates to the base path of the                   /usr/bin
                                            linker

*$(ToolchainName)*                          Names of the used DefaultToolchain                  GCC

*$(/)*                                      Evalutes to the directory path seperator of         Windows: \\, Other: /
                                            the current platform

*$(:)*                                      Evaluates to the path variable seperator            Windows: ;, Other: :
                                            of the current platform
========================================    ===============================================     ========================================

Environment variables
*********************

Usually used if system dependent stuff is needed like path to a specific tool etc.

Nested variables
****************
It is also possible to nest variables.

Example:

.. code-block:: console

    $(ABC$(DEF)GH)


Complex variables
*****************

bake supports one complex variable:

.. code-block:: console

    $(OutputDir,$(TheProject),$(TheConfig))

This will evaluate to the output directory of a specific configuration.

Notes and warnings
******************

Equal variables in the main config:

========================================    ========================================
Variable                                    Is equal to
========================================    ========================================
$(MainConfigName)                           $(ConfigName)

$(MainProjectName)                          $(ProjectName)
========================================    ========================================

.. warning::

    Variables in Dependency definitions are not allowed!