Double Underscore Name Mangling

Hard ⏱ 18 min 32% acceptance ★★★★☆ 4.2

Attributes named __secret (two leading underscores) are rewritten to _ClassName__secret. Build Vault storing __pin from the constructor with a method check(pin) comparing against it. Then write the module-level function crack(vault) that reads the pin anyway via the mangled name — proving mangling is collision-avoidance, not security.

Examples

Example 1

Input

Vault('1234').check('1234')

Output

True

Explanation

Inside the class the name works unmangled.

Example 2

Input

crack(Vault('1234'))

Output

'1234'

Explanation

The mangled attribute is reachable from outside.

Constraints

Use exactly two leading underscores.
crack must use the mangled form.

Topics

OOPname mangling

Companies

GoogleMetaOracle

Hints

Hint 1

The mangled name is _Vault__pin.

Hint 2

getattr(vault, "_Vault__pin") or direct attribute access.

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