let the user define the location of global directory by setting environment variables

[nopid]

Walnut needs a main directory where artifacts are stored. By default, it is the current directory or the directory below if bin.

Walnut/src/main/java/Main/Session.java

Lines 48 to 58 in dc63950

	public static void setPathsAndNames() {
	String path = System.getProperty("user.dir");
	if (path.endsWith("bin"))
	mainWalnutDir = "../";
	name = SESSION_NAME + "/" +
	LocalDateTime.now().format(DateTimeFormatter.ofPattern(FRIENDLY_DATE_TIME_PATTERN)) + "/";
	if (sessionWalnutDir == null) {
	sessionWalnutDir = mainWalnutDir + name;
	}
	createSubdirectories();
	}

In the Walnut Jupyter kernel, I have been using environment variables to specify where Walnut is located:

• WALNUT_HOME is the main directory location;
• WALNUT_JAR is the main jar file location.

Basically, the kernel launches a process that runs something like

cd $WALNUT_HOME
java -Xmx$WALNUT_MEM -jar $WALNUT_JAR

Proposal for improvement: let the user specify the Walnut main directory by setting the WALNUT_HOME environment variable as the default location for the main directory. If set, this variable would be used as the default value for mainWalnutDir.

This will allow users to install Walnut where they want and have Walnut find it on startup.

[dvberkel]

This is a very nice idea.

I know that the Radboud university wanted to provide Walnut system wide, but it really isn't well suited to that use-case

[jn1z]

Alternatively, passing it via the command line would match the format of #13

[nopid]

Sure, a command line argument would also be nice, but it handle quite different situations. The environment variable can be set once and for all to let all your walnut invocation use a common main directory. It goes with @dvberkel comment on system wide installation.

[jn1z]

I've added this as a command-line parameter in case that works for you. This should also work for system-wide installation. If you don't want to pass the home dir every time, any kind of script can pass this.

I'm not really a fan of having two separate approaches for session and home dirs; environment variables also make testing more difficult.