Ensure pixels have __len__ before checking with len()#2
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Ensure pixels have __len__ before checking with len()#2
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In Astro Pi we were getting TypeErrors when checking len() on non-iterable variables, e.g. when a user calls set_pixel() with just three arguments. This PR ensures that the pixel has a __len__ attribute before testing its length. Also fixes checking the pixel list in set_pixels.
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Feb 27, 2026
…`sense_hat.py` errors (#1348) Closes RaspberryPiFoundation/digital-maintenance-team#7 This commit specifically fixes the issue triggered by using incorrect arguments in the `set_pixel` and `set_pixels` functions. `TypeError: object of type 'int' has no len() on line 1081 of sense_hat.py` I've added an explicit check to see if the pixel object has a `__len__` attribute. I've opened an identical PR on the [Sense Hat library](RaspberryPiFoundation/sense_hat#1), and [here](RaspberryPiFoundation/python-sense-hat#2) and [here](astro-pi/python-sense-hat#151)! ## Traceback mangling I changed the error message when the filename is `./sense_hat.py` to point to the next file in the stack, hopefully the user's code. The issue with this is that it effectively masks errors in the `sense_hat` library, blaming the user instead. At the moment it only catches specific errors: `ValueError`, `RuntimeError` which are specifically mentioned in the sense hat shim. ## Package update This also updates the package version to 0.34.7. ## Example python ```python # Import the libraries from sense_hat import SenseHat from time import sleep # Set up the Sense HAT sense = SenseHat() sense.set_pixel(1, 2, 3) # Or: sense.set_pixels(1) # Or: # sense.set_pixels([1]*64) ``` ## Before <img width="1473" height="347" alt="image" src="https://github.com/user-attachments/assets/0f8f6e1d-42bc-454f-88b5-a7c22568c012" /> ## After Tested on https://staging-editor-static.raspberrypi.org/branches/1348_merge/web-component.html <img width="1200" height="390" alt="image" src="https://github.com/user-attachments/assets/f30ff39c-0c47-4dbf-a7ae-d1aed3951259" /> --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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Pull request overview
This PR improves error handling in the Sense HAT library's pixel manipulation functions by adding hasattr checks before calling len(). This prevents TypeError exceptions when users pass non-iterable arguments (e.g., integers) to functions expecting pixel tuples or lists, replacing them with more informative ValueError exceptions.
Changes:
- Added
hasattr(pixel_list, '__len__')check inset_pixels()before validating pixel list length - Added
hasattr(pix, '__len__')check inset_pixels()before validating individual pixel length - Refactored
set_pixel()to consolidate pixel validation withhasattrcheck, removing early length check that could raiseTypeError
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jamiebenstead
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Mar 3, 2026
…`sense_hat.py` errors (#1348) Closes RaspberryPiFoundation/digital-maintenance-team#7 This commit specifically fixes the issue triggered by using incorrect arguments in the `set_pixel` and `set_pixels` functions. `TypeError: object of type 'int' has no len() on line 1081 of sense_hat.py` I've added an explicit check to see if the pixel object has a `__len__` attribute. I've opened an identical PR on the [Sense Hat library](RaspberryPiFoundation/sense_hat#1), and [here](RaspberryPiFoundation/python-sense-hat#2) and [here](astro-pi/python-sense-hat#151)! ## Traceback mangling I changed the error message when the filename is `./sense_hat.py` to point to the next file in the stack, hopefully the user's code. The issue with this is that it effectively masks errors in the `sense_hat` library, blaming the user instead. At the moment it only catches specific errors: `ValueError`, `RuntimeError` which are specifically mentioned in the sense hat shim. ## Package update This also updates the package version to 0.34.7. ## Example python ```python # Import the libraries from sense_hat import SenseHat from time import sleep # Set up the Sense HAT sense = SenseHat() sense.set_pixel(1, 2, 3) # Or: sense.set_pixels(1) # Or: # sense.set_pixels([1]*64) ``` ## Before <img width="1473" height="347" alt="image" src="https://github.com/user-attachments/assets/0f8f6e1d-42bc-454f-88b5-a7c22568c012" /> ## After Tested on https://staging-editor-static.raspberrypi.org/branches/1348_merge/web-component.html <img width="1200" height="390" alt="image" src="https://github.com/user-attachments/assets/f30ff39c-0c47-4dbf-a7ae-d1aed3951259" /> --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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In Astro Pi we were getting TypeErrors when checking len() on non-iterable variables, e.g. when a user calls set_pixel() with just three arguments.
This PR ensures that the pixel has a len attribute before testing its length.
Also fixes checking the pixel list in set_pixels.