I am a Mac user and have the unofficial port of OpenJDK7. However because this is not released software, I mainly want to still use Java 6. I have renamed the java and javac commands for Java7 to "java7" and "javac7" respectively.

It would be very helpful if there were a command line to the Frege compiler to tell it to use a different command for Java compilation, i.e. "javac7" instead of "javac".

This I wanted to do anyway, it's not a big deal.

I wonder if we can do this via properties like

java -Dfrege.javac=javac7 -jar fregec.jar .....

Such a property could also be set permanently with some java tool. So one did not have to make changes to Makefiles or build tool configuration and could still use a different compiler.

This is now implemented in releases from 3.17.148 on like announced in my previous comment. Note that the property is the first half of the commandline, the rest will be supplied dynamically. Hence, it is not only possible to change the name or path but also, for instance, to specify further parameters for the java compiler. Run

java -cp build frege.compiler.Main -help

for syntax and an example.