vaatimustiedostot

Vaatimustiedostot, or requirements files, are plain text files that list the dependencies needed for a Python project. These files are typically named requirements.txt and are used to ensure that all necessary packages are installed in the correct versions. This is crucial for reproducibility, allowing others to set up the same development environment or deploy the project consistently.

The format of a requirements file is straightforward. Each line specifies a package, optionally with a version specifier. For example, `requests` would install the latest version of the `requests` library, while `requests==2.28.1` would install a specific version. Version specifiers can also include comparison operators like `>`, `<`, `>=`, `<=`, and `!=`. Lines starting with a hash symbol (#) are treated as comments and are ignored.

To install the packages listed in a requirements file, developers use the pip package installer. The command `pip install -r requirements.txt` reads the file and installs all specified dependencies. This command is a standard practice in Python project management.

Furthermore, requirements files play a vital role in virtual environments. By creating a virtual environment for a project and then generating a requirements file from it, developers can easily share their project's dependencies. This prevents conflicts between different projects that might require different versions of the same library. The command `pip freeze > requirements.txt` is commonly used to generate such a file from the currently active virtual environment. In essence, vaatimustiedostot are a simple yet powerful mechanism for managing and sharing Python project dependencies.