A guide to modern C++ coding patterns for versions 17, 20, and 23, including safe resource ownership, value-based design, and standard library types.

Use it when choosing smart pointers, handling errors, applying move semantics, naming code, and writing modern C++ tests.

It helps avoid manual memory-management errors and makes C++ code more predictable, readable, and efficient.

How irahardianto/rugged-gemini configures Claude Code and Gemini CLI

Reuse

Borrowing it

Nothing to install: this file belongs to irahardianto/rugged-gemini. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/irahardianto/rugged-gemini/main/.gemini/skills/cpp-idioms/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/irahardianto/rugged-gemini

Made for: Claude Code, Gemini CLI.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/irahardianto/rugged-gemini/cpp-idioms/github.svg)](https://agentmods.dev/skills/irahardianto/rugged-gemini/cpp-idioms)

Your own site

<a href="https://agentmods.dev/skills/irahardianto/rugged-gemini/cpp-idioms"><img src="https://agentmods.dev/badge/skills/irahardianto/rugged-gemini/cpp-idioms/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/irahardianto/rugged-gemini/cpp-idioms"><img src="https://agentmods.dev/badge/skills/irahardianto/rugged-gemini/cpp-idioms.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 540 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00000	$0.00540
Opus 5.5	$0.00000	$0.00216
Sonnet 5.5	$0.00000	$0.00108
Haiku 4.5	$0.00000	$0.00054

Measured 1mo ago against content hash a328b5ed7bab, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cpp-idioms scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.gemini/skills/cpp-idioms/SKILL.md · 58 lines

What it actually says

C++ Idioms and Patterns

Modern C++ (17/20/23) rewards RAII, value semantics, and zero-cost abstractions. Lean into the type system and smart pointers. Idiomatic C++ = safe, deterministic, performant.

Scope: C++ coding idioms. Test naming: GEMINI.md § Testing Strategy.

Ownership and Memory

RAII — resources tied to object lifetime. No manual new/delete.
std::unique_ptr for exclusive ownership, std::shared_ptr only when sharing is necessary.
Move semantics — prefer moving over copying for expensive types.

Error Handling

std::expected (C++23) or Result types for expected failures.
Exceptions for exceptional conditions only. Never for control flow.
noexcept on move constructors and destructors.

Modern Features

std::string_view for read-only string parameters (no allocation).
constexpr for compile-time evaluation.
Structured bindings: auto [id, title] = getTask();
std::optional for nullable values.

Naming

PascalCase for types. camelCase or snake_case for functions (project-consistent).
_ suffix for private members: storage_, logger_.
No Hungarian notation.

Testing

Google Test or Catch2. Google Mock for interface mocking.

Formatting and Static Analysis

Tool	Purpose	Command
`clang-format`	Formatting	`clang-format -i src/*/.cpp`
`clang-tidy`	Static analysis	`clang-tidy src/*.cpp --`
`cppcheck`	Bug detection	`cppcheck --enable=all src/`
AddressSanitizer	Memory errors	`-fsanitize=address`
ThreadSanitizer	Race conditions	`-fsanitize=thread`

Code Idioms and Conventions GEMINI.md § Code Idioms and Conventions
Resources and Memory Management @.gemini/skills/resources-and-memory-management/SKILL.md
Concurrency and Threading Principles @.gemini/skills/concurrency-and-threading-principles/SKILL.md

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

1mo ago First seen · 58 lines · 0 tokens per session scan A a328b5ed7bab

Subscribe to this mod's changes

cpp-idioms is a skill published in the GitHub repository irahardianto/rugged-gemini (5 stars, last pushed 5mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 540 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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rugged-gemini: Skill for Claude Code