Creating a C++ Templating System

Problem

At a certain point in competitive programming, the bottleneck shifts.

You are no longer blocked by basic algorithm knowledge. You are blocked by repeatedly rewriting the same scaffolding: fast I/O, binary search shells, DSU, segment tree variants, graph utilities, and utility macros. Problems are still observation-heavy, but too much energy goes into boilerplate that has already been solved.

Most template setups I saw fell into two extremes:

• A 2000-line all-in-one template packed with advanced helpers that most problems will never need
• Something that gets the job done with simpler macros and helpers

Neither felt right. One did too much, the other did too little.

I wanted a system that was:

• Fast during contests
• Modular enough to stay clean
• Easy to bundle into a single, short submission file

Approach

Version 1

I started with modular headers.

Using #include <helper.h>, I could import only what I needed: prefix sums, graph traversal snippets, modular arithmetic helpers, etc. My template.cpp stayed small with a standard solve() + main() shell and common contest utilities.

This was clean for local development, but it had one obvious problem: you cannot submit multi-file includes on most OJ platforms. The workaround was manual copy-paste.

Version 2

Manual copy-paste worked for a while, then became a tax.

As problems grew, this process got slow and produced bloated files full of unused helpers. So I built a bundler.

I tagged exportable blocks in headers with comment markers like:

• // export begin: <name>
• // export end: <name>

Then I wrote a Python script (with argparse) and wired it into my PowerShell profile as cbundle.

As soon as dependencies showed up, the first version became brittle. Some exported blocks required others to exist first. I added explicit dependency metadata and a recursive resolver, and for certain classes I moved member implementations out of class definitions to make extraction easier.

At that point, the workflow clicked:

1. Solve locally with modular includes
2. Run cbundle
3. Submit one minimal expanded file with only used pieces

Improvements

• Stripped comments and extra whitespace in the bundle step
• Added recursive dependency resolution for exported blocks
• Added auto-detection of the most recently edited .cpp file with a confirmation prompt

Tradeoffs

The biggest issue is backward compatibility.

As headers evolved, function signatures and member naming conventions changed. Old unbundled files could break unexpectedly after a “small” helper refactor. Bundled historical submissions stayed safe, but ongoing local workflows were less stable than I wanted.

My mitigation:

• Legacy flags for behavior changes
• Aliases for renamed members
• More conservative edits to heavily reused helpers

Results

• Problems that used to require pages of repeated setup now start almost immediately
• Implementation speed improved significantly, with large gains on known problem families
• The template stays extensible without collapsing into one giant file

What Did We Learn?

• A useful tooling system takes multiple iterations, not one clean design pass
• Backward compatibility is part of product quality, even for personal tools
• Modularity only helps if dependency handling is reliable
• Simplicity beats cleverness in contest tooling

What I Would Improve Next

• Add automated tests that validate each exported block in isolation
• Add a tag/dependency linter to catch malformed exports before bundling
• Add a “compatibility mode” report showing which helpers changed behavior