adds taskmanager

learning_python3.md

@@ -1706,6 +1706,115 @@ for login in my_login_list:
         print("\t{}: {}".format(key, login[key]))
 ```
 
+# Coding challenge - Task manager
+
+Can you create me a *task manager* please?
+I made one that is run from the command line with different arguments to modify it's behaviour.
+If this looks too challenging I can tell you that the *full code* is 64 lines long, including empty lines!
+Those of you who already tried out [argparse](https://realpython.com/command-line-interfaces-python-argparse/) in the previous challenges will probably understand what's going on here.
+Those who did not I urge you to have a look at the link above and don't hesitate to ask for help!
+
+```bash
+➜  python_course_doc git:(master) ✗ python3 test.py --help              
+usage: test.py [-h] [--file FILE] {add,delete,show} ...
+
+positional arguments:
+  {add,delete,show}
+    add                 adds a todo item to you todo list
+    delete              deletes an item from your todo list
+    show                show all your tasks
+
+optional arguments:
+  -h, --help            show this help message and exit
+  --file FILE, -f FILE  path to your todo file
+➜  python_course_doc git:(master) ✗ python3 test.py show  
+ID: 0 --- buy milk
+ID: 1 --- clean house
+ID: 2 --- test my code
+➜  python_course_doc git:(master) ✗ python3 test.py add write some documentation
+➜  python_course_doc git:(master) ✗ python3 test.py show                        
+ID: 0 --- buy milk
+ID: 1 --- clean house
+ID: 2 --- test my code
+ID: 3 --- write some documentation
+➜  python_course_doc git:(master) ✗ python3 test.py delete 2
+➜  python_course_doc git:(master) ✗ python3 test.py show    
+ID: 0 --- buy milk
+ID: 1 --- clean house
+ID: 2 --- write some documentation
+➜  python_course_doc git:(master) ✗ 
+```
+
+<details>
+  <summary>Spoiler warning</summary>
+
+```python3
+import argparse
+import pathlib
+
+
+def read_taskfile(taskfile_path):
+    tasks = []
+    if not pathlib.Path(taskfile_path).exists():
+        return tasks
+    with open(taskfile_path, "r") as fp:
+        lines = fp.readlines()
+    for line in lines:
+        task = line.strip()
+        tasks.append(task)
+    return tasks
+
+
+def write_taskfile(taskfile_path, tasks):
+    with open(taskfile_path, "w") as fp:
+        for task in tasks:
+            fp.write("{}\n".format(task))
+
+
+def show_tasks(tasks):
+    counter = 0
+    for task in tasks:
+        print("ID: {} --- {}".format(counter, task))
+        counter += 1
+
+
+def add_task(tasks, task):
+    tasks.append(task)
+    return tasks
+
+
+def delete_task(tasks, task_id):
+    tasks.pop(task_id) 
+    return tasks
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--file", "-f", default="./todo.tasks", help="path to your todo file")
+    subparser = parser.add_subparsers()
+    add = subparser.add_parser("add", help="adds a todo item to you todo list")
+    add.add_argument("task", nargs="*")
+    delete = subparser.add_parser("delete", help="deletes an item from your todo list")
+    delete.add_argument("idx", type=int, nargs="*")
+    show = subparser.add_parser("show", help="show all your tasks")
+    show.add_argument("show", action="store_true")
+    args = parser.parse_args()
+
+    taskfile = args.file
+    tasks = read_taskfile(taskfile)
+
+    if "task" in args:
+        tasks = add_task(tasks, " ".join(args.task))
+        write_taskfile(taskfile, tasks)
+    elif "idx" in args:
+        for idx in args.idx:
+            tasks = delete_task(tasks, idx)
+        write_taskfile(taskfile, tasks)
+    elif args.show:
+        show_tasks(tasks)
+```
+</details>
+
 ## csv, JSON and yaml
 
 # Now for some useful scripting