Added task Executing Modules as scripts

Author: sofiiako

Modules and packages/Executing modules as scripts/__init__.py

@@ -0,0 +1,10 @@
+def func():
+    print('This is a message from the function in the imported module.')
+
+
+print(f'This is a message from {__name__}.')
+
+# Make a change here.
+if __name__ == "__main__":
+    print('This should not be printed')
+

Modules and packages/Executing modules as scripts/some_module.py

@@ -0,0 +1,23 @@
+type: edu
+files:
+- name: task.py
+  visible: true
+  placeholders:
+  - offset: 65
+    length: 18
+    placeholder_text: '# Call func() from the imported module'
+  - offset: 107
+    length: 100
+    placeholder_text: print('This should be printed ONLY when task.py is called directly.')
+- name: tests/test_task.py
+  visible: false
+- name: __init__.py
+  visible: false
+- name: tests/__init__.py
+  visible: false
+- name: some_module.py
+  visible: true
+  placeholders:
+  - offset: 155
+    length: 66
+    placeholder_text: print('This should not be printed')

Modules and packages/Executing modules as scripts/task-info.yaml

@@ -0,0 +1,67 @@
+## Executing modules as scripts
+
+A Python module is a file containing executable statements as well as function or class definitions. 
+These statements are executed the first time the module name is encountered in an `import` statement.
+The file name is the module name with the suffix .py appended. Within a module, the 
+module’s name (as a string) is available as the value of the global variable `__name__`.
+A module can contain executable statements as well as function or class definitions. 
+These statements are executed the first time the module name is encountered in an `import` statement.
+
+When you run a module **directly** (that is, not by importing it into another one),
+the code in the module will be executed, just as if you imported it, but with the 
+`__name__` set to `"__main__"`. 
+
+You can use `__name__` and `__main__` like this:
+
+```python
+if __name__ == "__main__":
+   # Do something here
+```
+
+The statements inside this block will be executed only if the module is run directly and not through import
+into another module. For example, let's consider two files:
+
+main_program:
+```python
+import some_module
+
+print(f"main_program __name__ is: {__name__}")
+
+if __name__ == "__main__":
+   print("main_program executed directly")
+else:
+   print("Main program executed when imported")
+```
+
+some_module:
+```python
+print(f"some_module __name__ is: {__name__}")
+
+if __name__ == "__main__":
+   print("some_module executed directly")
+else:
+   print("some_module executed when imported")
+```
+
+Output after running `main_program`:
+```text
+some_module __name__ is: some_module
+some_module executed when imported
+main_program __name__ is: __main__
+main_program executed directly
+```
+
+Output after running `some_module`:
+```text
+some_module __name__ is: __main__
+some_module executed directly
+```
+
+Modify `task.py` and `some_module.py` so that when you run task.py your output is as follows:
+
+```text
+This is a message from some_module.
+This is a message from __main__.
+This is a message from the function in the imported module.
+This should be printed ONLY when task.py is called directly.
+```

Modules and packages/Executing modules as scripts/task.md

@@ -0,0 +1,9 @@
+import some_module
+
+print(f'This is a message from {__name__}.')
+some_module.func()
+
+# Make a change here.
+if __name__ == "__main__":
+    print('This should be printed ONLY when task.py is called directly.')
+

Modules and packages/Executing modules as scripts/task.py

@@ -0,0 +1,28 @@
+import unittest
+import contextlib
+import io
+
+
+f = io.StringIO()
+with contextlib.redirect_stdout(f):
+    import task
+
+output = f.getvalue().split('\n')
+
+
+class TestCase1(unittest.TestCase):
+    def test_some_module(self):
+        test_out = ['This is a message from some_module.', 'This is a message from task.', 'This is a message from the function in the imported module.', '']
+        self.assertEqual(test_out, output, msg='Something is wrong, actual output does not match expected.')
+
+    def test_some_main(self):
+        self.assertFalse("This should not be printed" in output,
+                         msg='You should move the last print statement in some_module into the `main` block.')
+
+    def test_main_main(self):
+        self.assertFalse("This should be printed ONLY when task.py is called directly." in output,
+                         msg='You should move the last print statement in task.py into the `main` block.')
+
+    def test_main_func(self):
+        self.assertTrue('This is a message from the function in the imported module.' in output,
+                        msg='Do not forget to call the function from the imported module.')

Modules and packages/Executing modules as scripts/tests/__init__.py

@@ -2,4 +2,5 @@ content:
 - Import module
 - Built-in modules
 - From import
-- Packages
+- Packages
+- Executing modules as scripts