What are __slots__?

Understanding Python __slots__ in interview contexts

This is an easy Python language-knowledge question that tests whether you understand how Python manages object memory and attribute storage. Interviewers ask it to gauge familiarity with Python internals and whether you can optimize code for performance-sensitive applications.

The question probes the difference between Python's default attribute-storage mechanism and an alternative approach that can reduce memory overhead. Candidates who answer well typically explain the trade-offs: what you gain in efficiency versus what you lose in flexibility. This matters in systems where you instantiate millions of lightweight objects, such as market-data handlers or position trackers in a trading system.

• Object memory layout in Python
• The role of __dict__ in attribute storage
• Use cases for memory optimization in data-heavy applications