Python Virtual Environment Setup

Creating isolated Python environments is crucial for managing project dependencies and avoiding conflicts. This challenge focuses on the fundamental skill of creating and activating a Python virtual environment using the built-in venv module.

Problem Description

Your task is to write a series of commands (or a script that executes these commands) to create a new Python virtual environment for a specific project. This environment should be activated and then a simple package should be installed within it to verify its isolation.

What needs to be achieved:

1. Create a new, isolated Python virtual environment.
2. Activate this virtual environment.
3. Install a specified package within the activated environment.
4. Demonstrate that the package is installed only in the virtual environment.

Key Requirements:

• Use Python's built-in venv module.
• The virtual environment should be created in a designated directory.
• The activation process should be correctly described for a common operating system.
• A specific, lightweight package should be installed.

Expected Behavior: When the commands are executed sequentially, a new directory containing the virtual environment will be created. Upon activation, your shell prompt should indicate that you are inside the virtual environment. After installing the package, running a command to list installed packages should show the newly installed package, and running the same command outside the activated environment should not show the package.

Important Edge Cases:

• What happens if the virtual environment directory already exists? (The venv module handles this gracefully by default.)
• Ensuring the correct activation script is used for different operating systems (e.g., Windows vs. macOS/Linux).

Examples

Example 1: Creating and activating on macOS/Linux

Input:
Project Directory: my_python_project
Virtual Environment Name: venv
Package to Install: requests

Commands to Execute:
1. Navigate to the project directory: cd my_python_project
2. Create the virtual environment: python3 -m venv venv
3. Activate the environment: source venv/bin/activate
4. Install the package: pip install requests
5. Verify installation: pip freeze
6. Deactivate the environment: deactivate
7. Verify deactivation: pip freeze

Output:
(After step 3, the prompt changes to something like '(venv) user@hostname:~/my_python_project$')
(After step 5, output includes 'requests==X.Y.Z')
(After step 7, output does NOT include 'requests==X.Y.Z' unless it was globally installed)

Explanation:
The commands first create a virtual environment named 'venv' inside 'my_python_project'.
Activating it modifies the shell's PATH.
'requests' is installed only within this isolated environment.
'pip freeze' confirms its presence when activated and its absence when deactivated.

Example 2: Creating and activating on Windows (Command Prompt)

Input:
Project Directory: my_python_project
Virtual Environment Name: venv
Package to Install: requests

Commands to Execute:
1. Navigate to the project directory: cd my_python_project
2. Create the virtual environment: python -m venv venv
3. Activate the environment: venv\Scripts\activate.bat
4. Install the package: pip install requests
5. Verify installation: pip freeze
6. Deactivate the environment: deactivate
7. Verify deactivation: pip freeze

Output:
(After step 3, the prompt changes to something like '(venv) C:\Users\User\my_python_project>')
(After step 5, output includes 'requests==X.Y.Z')
(After step 7, output does NOT include 'requests==X.Y.Z' unless it was globally installed)

Explanation:
Similar to macOS/Linux, but uses Windows-specific activation script path and command.

Constraints

• The Python version used to create the virtual environment should be Python 3.6 or higher.
• The user is assumed to have Python installed and accessible in their system's PATH.
• The solution should focus on the command-line interface.
• The chosen package for installation (requests) is guaranteed to be available on PyPI.

Notes

• The venv module is the standard way to create virtual environments in modern Python.
• Consider how you would present this as a runnable script or a clear set of instructions for a user.
• Pay close attention to the activation script path, as it differs between operating systems.
• The pip freeze command is a good way to list installed packages.