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# Signals
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Flask provides a signals system for hooking into the application lifecycle and request processing events.
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## Capabilities
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### Signal Objects
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```python { .api }
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template_rendered: NamedSignal
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before_render_template: NamedSignal
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request_started: NamedSignal
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request_finished: NamedSignal
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request_tearing_down: NamedSignal
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got_request_exception: NamedSignal
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appcontext_tearing_down: NamedSignal
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appcontext_pushed: NamedSignal
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appcontext_popped: NamedSignal
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message_flashed: NamedSignal
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```
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## Usage Examples
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### Basic Signal Usage
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```python
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from flask import Flask
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from flask.signals import request_started
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app = Flask(__name__)
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def log_request(sender, **extra):
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    print(f"Request started for {sender.name}")
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request_started.connect(log_request, app)
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```