Java: Add 'EnvironmentConfiguredTracer'

Adding 'ppaml_tracer_init_from_env' (commit b9dfb8d0) makes the Java
code substantially more complicated, as it introduces a second mechanism
to construct 'Tracer's.  While I could simply provide two constructors
in the 'Tracer' class, this would make for an ugly and dangerous
implementation; after all, the life cycle of a tracer configured
explicitly is noticeably different from the life cycle of a tracer
configured by sourcing environment variables.  Instead, I’ve changed
'Tracer' to be an interface implemented by 'ExplicitlyConfiguredTracer'
and 'EnvironmentConfiguredTracer'.

This is an API-breaking change.

1 files changed, 2 insertions, 1 deletions

diff --git a/bindings/java/examples/src/com/galois/ppaml/tracer/examples/Simple.java b/bindings/java/examples/src/com/galois/ppaml/tracer/examples/Simple.java
index a698573..f4a6b99 100644
--- a/bindings/java/examples/src/com/galois/ppaml/tracer/examples/Simple.java
+++ b/bindings/java/examples/src/com/galois/ppaml/tracer/examples/Simple.java
@@ -3,6 +3,7 @@
 
 package com.galois.ppaml.tracer.examples;
 
+import com.galois.ppaml.tracer.ExplicitlyConfiguredTracer;
 import com.galois.ppaml.tracer.Phase;
 import com.galois.ppaml.tracer.Tracer;
 
@@ -72,7 +73,7 @@ public class Simple {
 
 	public static void main(String[] args) {
 		// Start ppamltracer.
-		Tracer tracer = new Tracer("/tmp/simple_report");
+		Tracer tracer = new ExplicitlyConfiguredTracer("/tmp/simple_report");
 
 		// Run the app.
 		(new Simple()).go(tracer);