Context manager scoping aligned with CPython

Author: JdeH

transcrypt/development/automated_tests/transcrypt/control_structures/__init__.py

@@ -10,6 +10,9 @@ def __exit__ (self, *args):
         self.counter += 99
 
 def run (autoTester):
+
+    # General control structure tests
+
     for index in range (10):
         autoTester.check (index)
 
@@ -80,15 +83,45 @@ def run (autoTester):
                 autoTester.check ('oceania')
             else:
                 autoTester.check ('anywhere') 
+                
+    # Context manager tests
 
-    with ContextManagerExample () as contextManagerExample:
-        pass
-        
-    autoTester.check (contextManagerExample.counter)
-
+    externalCounter1 = 0
+    with ContextManagerExample () as contextManagerExample1:
+        externalCounter1 += 1
+    autoTester.check ('ctx1', contextManagerExample1.counter, externalCounter1)
+    
+    externalCounter2 = 0
     with ContextManagerExample () as contextManagerExample2:
+        externalCounter2 += 1
         contextManagerExample2.counter += 100
-        
-    autoTester.check (contextManagerExample2.counter)
-                
-                
+        externalCounter3 = 0
+        with ContextManagerExample () as contextManagerExample3:
+            externalCounter3 += 1
+            contextManagerExample2.counter += 100     
+            externalCounter3 += 2
+            contextManagerExample3.counter += 200
+        autoTester.check ('ctx3', contextManagerExample3.counter, externalCounter3)
+        externalCounter2 += 2
+        contextManagerExample2.counter += 200
+    autoTester.check ('ctx2', contextManagerExample2.counter, externalCounter2)
+
+    try:
+        externalCounter4 = 0
+        with ContextManagerExample () as contextManagerExample4:
+            externalCounter4 += 1
+            contextManagerExample4.counter += 100
+            externalCounter5 = 0
+            with ContextManagerExample () as contextManagerExample5:
+                externalCounter5 += 1
+                contextManagerExample5.counter += 100
+                raise Exception ()    
+                externalCounter5 += 2
+                contextManagerExample5.counter += 200  
+            externalCounter4 += 2
+            contextManagerExample4.counter += 200
+    except Exception as exception:
+        autoTester.check ('ctx6', exception)
+    finally:
+        autoTester.check ('ctx5', contextManagerExample5.counter, externalCounter5)
+        autoTester.check ('ctx4', contextManagerExample4.counter, externalCounter4) 

transcrypt/development/shipment/shipment_test.py

@@ -57,7 +57,7 @@ def test (relSourcePrepath, run, extraSwitches, messagePrename = '', nodeJs = Fa
     buildSwitch = '-b ' if build else ''
 
     # Compile with Transcrypt
-    os.system (f'{transpileCommand} -m {buildSwitch}-da -sf -n {transitSwitches}{extraSwitches}{sourcePrepath}{redirect}')
+    os.system (f'{transpileCommand} {buildSwitch}-da -sf -n {transitSwitches}{extraSwitches}{sourcePrepath}{redirect}')
 
     # Run back to back in CPython
     if run:

transcrypt/modules/org/transcrypt/__builtin__.js

@@ -119,7 +119,7 @@ export function __withblock__ (manager, statements) {
             }
         }
     }
-    else {
+    else {  // Close an open file object, even if it doesn't support context management
         statements ();
         manager.close ();
     }

transcrypt/modules/org/transcrypt/compiler.py

@@ -3322,44 +3322,47 @@ def visit_While (self, node):
     def visit_With (self, node):
         self.adaptLineNrString (node)
 
-        self.emit ('{{\n')
-        self.indent ()
-        
         for item in node.items:
+            self.emit ('var ')                      # Should be in surrounding scope but may be overwritten, so use var rather than let
             if (item.optional_vars):
-                self.emit ('var ')
-                self.visit (item.optional_vars)     # Keep this visit to register with __all__
+                self.visit (item.optional_vars)
                 withId = item.optional_vars.id
             else:
-                self.emit ('let ')
-                withId = self.nextTemp ('withid')   # Won't be registered, but is guaranteed not to be referenced
+                withId = self.nextTemp ('withid')
                 self.emit (withId)
 
             self.emit (' = ')
             self.visit (item.context_expr)
             self.emit (';\n')
 
-            self.emit('let ')
-            self.emit (self.nextTemp ('withfunc'))
-            self.emit (' = function() {{\n')
-            self.indent()
+            self.emit ('if (hasattr ({}, \'__enter__\')) {{\n', withId)
+            self.indent ()
+            self.emit ('try {{\n')
+            self.indent ()
+            self.emit ('{}.__enter__ ();\n', withId)
             self.emitBody (node.body)
+            self.emit ('{}.__exit__ ();\n', withId)
             self.dedent ()
-            self.emit('}};\n')
-
-            self.emit ('__withblock__(')
-            self.emit (withId)
-            self.emit (' , ')
-            self.emit (self.getTemp ('withfunc'))
-            self.emit (');\n')
-            
-            self.prevTemp ('withfunc')
+            self.emit ('}}\n')
+            self.emit ('catch ({}) {{\n', self.nextTemp ('except'))
+            self.indent ()
+            self.emit ('if (! ({0}.__exit__ ({1}.name, {1}, {1}.stack))) {{\n', withId, self.getTemp ('except'))
+            self.indent ()
+            self.emit ('throw {};\n', self.getTemp ('except'))
+            self.dedent ()
+            self.emit ('}}\n')
+            self.dedent ()
+            self.emit ('}}\n')
+            self.prevTemp ('except')
+            self.dedent ()
+            self.emit ('}}\n')
+            self.emit ('else {{\n')
+            self.indent ()
+            self.dedent ()
+            self.emit ('}}\n')
 
             if withId == self.getTemp ('withid'):
                 self.prevTemp ('withid')
-            
-        self.dedent()
-        self.emit('}}')
 
     def visit_Yield (self, node):
         self.getScope (ast.FunctionDef, ast.AsyncFunctionDef) .containsYield = True