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Understanding Flask's Application Instance

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    hwahyeon
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app = Flask(__name__)

app = Flask(__name__) is the code used to create a Flask application instance. In this code, the __name__ variable holds the name of the currently running file or module.

  • When the file is executed directly (e.g., python example.py), __name__ is assigned the value "__main__".
  • When the file is imported as a module (e.g., import example), __name__ is assigned the module's name (e.g., "example").

An application instance represents the Flask application itself.

  • This object interacts with WSGI (Web Server Gateway Interface) to handle incoming requests and generate appropriate responses.
  • Developers use the application instance to define routes, configure settings, and register extensions.
  • When the Flask application runs, the application instance manages all interactions between the server and the request-response cycle.

In short, the application instance serves as the "central control hub" of a Flask application and plays a critical role in the request-response lifecycle.