Drill
Idiom contrast
Rewrite three of your own methods, then delete the classes you did not need. Ten problems twice: Java-shaped, then idiomatic.
Python in Seven Days
A conversion week for senior engineers who already ship in C#, Java, PHP, JavaScript or PowerShell: idiomatic Python, the questions interviewers actually ask, and something honest to talk about.
Created by Baljeet Dogra
Course Objectives
- Write Python that does not read as Java with different punctuation.
- Answer the language questions interviewers actually ask — including the GIL — in ninety seconds, then go deeper.
- Solve a coding problem in Python without fumbling syntax.
- Ship a small artefact and an honest conversion story, not a fabricated five-year history.
What you will produce
Build
Honest artefact
A CLI, API, pipeline or PowerShell rewrite with type hints, pytest, a README of trade-offs, and a GitHub history you can defend.
Prep
Spoken question bank
Thirty questions rehearsed aloud, two recorded mocks, and the narrative: what you built last week and where C# instincts were wrong.
7 days curriculum
Expand a part for the syllabus. Content stays searchable when closed.
00 Setup and syntax Before Day 1
Install first. Then type the surface of the language. Then the memory picture so Day 1 is names-on-a-heap, not punctuation.
- 0.1 Setup and positioning — toolchain, conversion sentence
- 0.2 Language familiarisation —
def,if/elif, the for-loop family,lambda, literals, f-strings - 0.3 How memory works — names, heap, refcount, cyclic GC
01 Core language and the mental model Day 1
Three labs, one day. 1.1 is the object model. 1.2 is calls and scope. 1.3 is the spoken gate — until twelve near-certain cards are clean twice, Day 1 is not finished.
- 1.1 Mental model — names, aliasing,
is/==, copy,None, mutable defaults - 1.2 Calls and scope —
*args/**kwargs, keyword-only, LEGB,enumerate/zip, slicing, truthiness - 1.3 Speak it — same bank, follow-ups, freeze tracking. Day 1 ends here.
02 Idiomatic Python Day 2
Highest-leverage day. Stop sounding like a Java developer: comprehensions, generators, EAFP, and the standard library that makes you look fluent.
- Comprehensions and
yield - Iterator protocol
- EAFP over LBYL
collectionsanditertoolspathlib,Counter,enumerate
03 Functions, objects and the data model Day 3
The “explain how X works” questions: closures and late binding, decorators with wraps, context managers, dunders, MRO, dataclasses.
- Late binding in loops
- Decorators and
wraps - Context managers
__eq__/__hash__Protocol, ABC, dataclasses
04 Concurrency, memory and errors Day 4
The questions that separate senior from mid-level. The GIL in ninety seconds, threads vs processes vs asyncio, memory and exceptions.
- GIL and PEP 703
- ThreadPool vs ProcessPool
- asyncio vs parallelism
- Refcount and cyclic GC
- Exception chaining
05 Ecosystem and engineering practice Day 5
Sound like someone who ships Python: packages, venv/uv, pytest, type hints, then one role-shaped afternoon (web, data, AI, or automation).
src/layout and importsuv,venv,pyproject.toml- pytest fixtures and mocks
- Type hints and mypy
- Role track: FastAPI, pandas, LLM APIs, or CLI
06 Coding round and a real artefact Day 6
Ten timed problems out loud, then something genuinely yours — the honest answer to “what have you built in Python?”
- Twenty-minute drills
Counter,defaultdict, unpacking- Build with tests and README
- Honest conversion narrative
07 Interview preparation Day 7
Spoken drilling on the question bank, two mocks, then attack weak spots. Prepare questions about their stack, tests and typing.
- Near-certain questions
- Senior three-way GIL/asyncio
- Live-coding survival kit
- Questions that signal seniority
Who this is for
Senior engineers converting
You are fluent in C#, Java, PHP, JavaScript or PowerShell. You need Python as the delivery language, not a beginner syllabus.
Interview in the next month
You need credible language answers and a live-coding round you will not fumble — without claiming years of production Python.
Prerequisites
- You already ship production software in another language
- Comfortable in a terminal and Git
- Python 3.12+, uv, an editor with Python language intelligence (VS Code + Pylance, or Cursor with basedpyright), ruff, mypy, pytest — 45 minutes before Day 1. Then 0.2: type
def, loops andlambdauntil they are boring.
Not a fit if
- A first course in programming — start with Python for GenAI
- A week of Python sold as years of production scar tissue — this course is built for the honest conversion story
Related: Python for GenAI · Data Structures & Algorithms
Questions
Will a week make me a Python specialist?
No. A week gets you fluent syntax, idiomatic style, the language questions interviewers actually ask, and an artefact. It does not get you production scar tissue or a 45-minute deep dive on a Python system you supposedly built two years ago.
How should I position this on a CV?
“Fifteen years across C#, Java and JavaScript; I picked up Python recently and I am productive in it — here is something I built.” That is credible. Claiming years of Python is what the deep-dive round exists to catch.
I already know how to code. Is Python for GenAI better?
No. Python for GenAI is a foundation for people new to the language. This week assumes you already ship software and spends the time on the 30% that misleads a Java or C# developer.