== Introduction ==

The idea is that comparing integers in C++ is easier and faster than comparing strings. So each model input is assigned an enum. In the code you will see `IceVolumeAboveFloatationEnum` but the code interpret this word as the integer 682. Each enum has a number associated to it automatically by the compiler. See this [http://en.wikipedia.org/wiki/Enumerated_type wikipedia page] for more info.

== Add a new Enum ==

If you want to add a new Enum, the ONLY file that needs to be changed is src/c/shared/Enum/EnumDefinitions.h`. Open it with you favorite editor (vim) and add your new Enum. Make sure that:
 - It does not already exist (the compiler will tell you anyway)
 - It finishes with `Enum,`

Then you can run a synchronization script that will update the matlab and python Enum, StringToEnum and EnumToString automatically:

{{{
#!sh
cd $ISSM_DIR/src/c/shared/Enum/
./Synchronize.sh
}}}

You will then need to recompile the entire trunk (not just src/c), and there is no need to reconfigure:

{{{
#!sh
cd $ISSM_DIR/
make install
}}}

== Checking in the changes ==

In order to commit the new Enum, you will need to `svn add` the new matlab file in `$ISSM_DIR/src/m/enum`, and then commit all the files in `$ISSM_DIR/src/m/enum` and `$ISSM_DIR/src/c/shared/Enum`

NB : if you want to check if your Enum is added, you can type it in Matlab and it has to return a number.

NB 2 : if you are developing and making modifications on the source files on a cluster like GreenPlanet, when you want to add an Enum, don't forget to update on your local machine the folders `$ISSM_DIR/src/m/enum` and `$ISSM_DIR/src/c/shared/Enum` because the Matlab software you are using is on your local machine.