Settings with defaults

Write the codeMedium 2 stages

The mission dashboard has a default for every setting, and each user's profile stores only what they have changed. When a user opens the dashboard, the two have to be combined: their values where they set one, the default everywhere else.

Merge the settings, then make the merge reject settings that don't exist.

Build settings: the defaults, with the user's own values on top. Leave DEFAULTS unchanged, since every user shares it. Then print every setting:

units: imperial
language: en
telemetry_rate_hz: 10
dark_mode: True
alerts: all

DEFAULTS.copy() makes a separate dict, and settings.update(user_settings) overwrites the keys the user set.

Merge the settings

Defaults stay shared

Finish stage 1 to unlock this stage.

A user's profile has a typo: "dark_mod". With update() it becomes a sixth setting that nothing reads. Copy only the keys that exist in DEFAULTS, and report the others before the settings:

Unknown setting ignored: dark_mod
units: imperial
language: en
telemetry_rate_hz: 10
dark_mode: True
alerts: all

Loop over user_settings.items() and check each key with in DEFAULTS.

Reject unknown settings

Works for any profile

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Hints

Modifying Dictionaries

modifying-dictionaries.py

# A mission record that changes as the mission goes on
parker = {
    "name": "Parker Solar Probe",
    "launched": 2018,
    "orbits": 20,
    "status": "cruising",
}

# Assign to a key that does not exist yet and it gets added
parker["closest_km"] = 6100000
print(parker)

# The same syntax on an existing key overwrites the old value
parker["status"] = "perihelion pass"
parker["orbits"] = 21
print("Status:", parker["status"], "after", parker["orbits"], "orbits")

# update() applies several changes in one go
parker.update({"speed_kmh": 692000, "status": "record holder"})
print("Speed:", parker["speed_kmh"], "km/h")

# pop() removes a key and hands the value back to you
old_status = parker.pop("status")
print("Removed status was:", old_status)

# del removes a key without giving anything back
del parker["launched"]
print(parker)

# setdefault() only fills in a key that is missing
parker.setdefault("agency", "NASA")
parker.setdefault("name", "Something Else")
print("Name:", parker["name"], "| Agency:", parker["agency"])

Open the full example

script.py

PythonLn 1, Col 1Spaces: 4

Loading the Python environment…

Command-line arguments (sys.argv)

Separate arguments with commas. They're passed on every Run as sys.argv[1:].