Absolute Paths

If an actor reads a file that is referred to by a relative pathname instead of an absolute pathname, then codegen gets tricky because the generated code might not be in the same directory as the original model.

One solution would be to preprocess urls so that we expand properties when we read them in. Currently, the expression language will expand Java properties with the properties() function.

The user's home directory can be found with

properties("user.dir")

When vergil is started up, -Dptolemy.ptII.dir=$PTII is passed to the java interpreter, so we can get the $PTII directory with

properties("ptolemy.ptII.dir")

If an actor has Parameter that names a file to be read in, then we can use something like

"file:///" + property("ptolemy.ptII.dir") + "/README.txt"

to read in the $PTII/README.txt file