From 63684d00425ffea5c5c30ad3bf546bc01a3d0dd3 Mon Sep 17 00:00:00 2001
From: Jason Turner <jason@emptycrate.com>
Date: Wed, 8 Apr 2015 08:17:33 -0600
Subject: [PATCH] Add the ability to get the return value from 'use'

---
 cheatsheet.md                                 | 11 ++++++++++
 .../chaiscript/language/chaiscript_engine.hpp | 22 ++++++++++++++-----
 unittests/eval.chai                           |  2 ++
 unittests/eval_file.chai                      | 10 +++++++++
 unittests/use.chai                            |  4 +++-
 unittests/use.inc                             |  1 +
 6 files changed, 44 insertions(+), 6 deletions(-)
 create mode 100644 unittests/eval_file.chai

diff --git a/cheatsheet.md b/cheatsheet.md
index b8be1a92..fc229acb 100644
--- a/cheatsheet.md
+++ b/cheatsheet.md
@@ -258,4 +258,15 @@ print(get_value(m)); // prints "Value Is: a"
 
 
 
+# Built In Functions
+
+## Evaluation
+
+```
+eval("4 + 5") // dynamically eval script string and returns value of last statement
+eval_file("filename") // evals file and returns value of last statement
+use("filename") // evals file exactly once and returns value of last statement
+                // if the file had already been 'used' nothing happens and undefined is returned
+```
+
 
diff --git a/include/chaiscript/language/chaiscript_engine.hpp b/include/chaiscript/language/chaiscript_engine.hpp
index b4e52693..9ee75d68 100644
--- a/include/chaiscript/language/chaiscript_engine.hpp
+++ b/include/chaiscript/language/chaiscript_engine.hpp
@@ -297,6 +297,15 @@ namespace chaiscript
       }
     }
 
+    /// Evaluates the given string, used during eval() inside of a script
+    const Boxed_Value internal_eval_file(const std::string &t_filename) {
+      try {
+        return do_eval(load_file(t_filename), t_filename, true);
+      } catch (const exception::eval_error &t_ee) {
+        throw Boxed_Value(t_ee);
+      }
+    }
+
 
 
     /// Evaluates the given string, used during eval() inside of a script
@@ -369,6 +378,7 @@ namespace chaiscript
       m_engine.add(fun(static_cast<load_mod_2>(&ChaiScript::load_module), this), "load_module");
 
       m_engine.add(fun(&ChaiScript::use, this), "use");
+      m_engine.add(fun(&ChaiScript::internal_eval_file, this), "eval_file");
       m_engine.add(fun(&ChaiScript::internal_eval, this), "eval");
       m_engine.add(fun(&ChaiScript::internal_eval_ast, this), "eval");
 
@@ -457,7 +467,7 @@ namespace chaiscript
 
       union cast_union
       {
-        void (ChaiScript::*in_ptr)(const std::string&);
+        Boxed_Value (ChaiScript::*in_ptr)(const std::string&);
         void *out_ptr;
       };
 
@@ -531,7 +541,7 @@ namespace chaiscript
     /// requested file.
     ///
     /// \param[in] t_filename Filename to load and evaluate
-    void use(const std::string &t_filename)
+    Boxed_Value use(const std::string &t_filename)
     {
       for (const auto &path : m_usepaths)
       {
@@ -541,15 +551,17 @@ namespace chaiscript
           chaiscript::detail::threading::unique_lock<chaiscript::detail::threading::recursive_mutex> l(m_use_mutex);
           chaiscript::detail::threading::unique_lock<chaiscript::detail::threading::shared_mutex> l2(m_mutex);
 
+          Boxed_Value retval;
+
           if (m_used_files.count(appendedpath) == 0)
           {
             l2.unlock();
-            eval_file(appendedpath);
+            retval = eval_file(appendedpath);
             l2.lock();
             m_used_files.insert(appendedpath);
-           }
+          }
 
-          return; // return, we loaded it, or it was already loaded
+          return retval; // return, we loaded it, or it was already loaded
         } catch (const exception::file_not_found_error &) {
           // failed to load, try the next path
         }
diff --git a/unittests/eval.chai b/unittests/eval.chai
index 2f18aa41..4db72da2 100644
--- a/unittests/eval.chai
+++ b/unittests/eval.chai
@@ -1 +1,3 @@
 assert_equal(7, eval("3 + 4"))
+
+
diff --git a/unittests/eval_file.chai b/unittests/eval_file.chai
new file mode 100644
index 00000000..be9934e1
--- /dev/null
+++ b/unittests/eval_file.chai
@@ -0,0 +1,10 @@
+
+try {
+  eval_file("use.inc")
+  assert(true)
+
+  //we expect this second eval_file to fail because of a function redefinition
+  eval_file("use.inc")
+  assert(false)
+} catch (e) {
+}
diff --git a/unittests/use.chai b/unittests/use.chai
index efd587da..317cced2 100644
--- a/unittests/use.chai
+++ b/unittests/use.chai
@@ -1,4 +1,5 @@
-use("use.inc")
+var newfun = use("use.inc");
+
 
 assert_equal("hello", greet())
 
@@ -7,3 +8,4 @@ use("use.inc")
 
 assert_equal("hello", greet())
 
+assert_equal("world", newfun())
diff --git a/unittests/use.inc b/unittests/use.inc
index 28970935..0f9fea77 100644
--- a/unittests/use.inc
+++ b/unittests/use.inc
@@ -2,3 +2,4 @@ def greet {
   return("hello")
 }
 
+fun(){ "world" }