flag to control eval reader (*read-eval*) [issue 34], patch from jhawk28

src/clj/clojure/core.clj

@@ -4019,6 +4019,13 @@
 
   Defaults to true")
 
+(add-doc *read-eval*
+  "When set to logical false, the EvalReader (#=(...)) is disabled in the 
+  read/load in the thread-local binding.
+  Example: (binding [*read-eval* false] (read-string \"#=(eval (def x 3))\"))
+
+  Defaults to true")
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; helper files ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (alter-meta! (find-ns 'clojure.core) assoc :doc "Fundamental library of the Clojure language")
 (load "core_proxy")

src/jvm/clojure/lang/LispReader.java

@@ -903,6 +903,11 @@ else if(s.ns != null) //static method
 
 public static class EvalReader extends AFn{
 	public Object invoke(Object reader, Object eq) throws Exception{
+		if (!RT.booleanCast(RT.READEVAL.deref()))
+	    {
+		  throw new Exception("EvalReader not allowed when *read-eval* is false.");
+	    }
+
 		PushbackReader r = (PushbackReader) reader;
 		Object o = read(r, true, null, true);
 		if(o instanceof Symbol)

src/jvm/clojure/lang/RT.java

@@ -178,6 +178,7 @@ public class RT{
 		           new PrintWriter(new OutputStreamWriter(System.err, UTF8), true));
 final static Keyword TAG_KEY = Keyword.intern(null, "tag");
 final static public Var AGENT = Var.intern(CLOJURE_NS, Symbol.create("*agent*"), null);
+final static public Var READEVAL = Var.intern(CLOJURE_NS, Symbol.create("*read-eval*"), T);
 final static public Var MACRO_META = Var.intern(CLOJURE_NS, Symbol.create("*macro-meta*"), null);
 final static public Var MATH_CONTEXT = Var.intern(CLOJURE_NS, Symbol.create("*math-context*"), null);
 static Keyword LINE_KEY = Keyword.intern(null, "line");