1 files changed, 53 insertions, 0 deletions
diff --git a/modules/language/python/with.scm b/modules/language/python/with.scm
new file mode 100644
index 0000000..eab5c55
--- /dev/null
+++ b/modules/language/python/with.scm
@@ -0,0 +1,53 @@
+(define-module (language python with)
+  #:use-module (language python try)
+  #:use-module (language python exceptions)
+  #:use-module (oop pf-objects)
+  #:export (with))
+
+(define-syntax-rule (aif it p x y) (let ((it p)) (if it x y)))
+
+(define-syntax with
+  (syntax-rules ()
+    ((_ () . code)
+     (begin . code))
+    ((_ (x . l) . code)
+     (with0 x (with l . code)))))
+
+(define-syntax with0
+  (syntax-rules ()
+    ((_ (id exp) . code)
+     (let ((type   None)
+	   (value  None)
+	   (trace  None))
+       (aif exit (ref exp '__exit__)
+	    (aif enter (ref exp '__enter__)
+		 (try
+		  (lambda ()
+		    (let ((id (enter))) . code))
+		  (#:except #t =>
+		    (lambda (tag l)		      
+		      (set! type  (if (pyclass? tag)
+				      tag
+				      (aif it (ref tag '__class__)
+					   it
+					   tag)))		      
+		      (set! value
+			    (aif it (ref tag 'value)
+				 it
+				 (if (pair? l)
+				     (car l)
+				     None)))))
+		  #:finally
+		  (lambda ()		    
+		    (exit type value trace)))
+		 (raise TypeError "no __enter__ member"))
+	    (raise TypeError "no __exit__ member"))))
+	           
+    ((_ (exp) . code)
+     (with0 (id exp) . code))))
+		  
+	  
+     
+		  
+
+