design-patterns

A guide to implementing the 23 Gang of Four design patterns in Delphi, a programming language and development environment based on Object Pascal. It applies interfaces, reference-counted objects, and SOLID design principles.

In plain words
What is it for?
Use it when implementing patterns such as Factory, Strategy, Observer, Command, Adapter, Decorator, and State in Delphi.
Why use it?
It gives Delphi developers established structures for solving recurring software-design problems instead of designing each solution from scratch.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/secondlifes/delphi-expert/design-patterns
Any agent
npx skills add SecondLifes/delphi-expert --skill design-patterns
Clone the repo
git clone --depth 1 https://github.com/SecondLifes/delphi-expert

Made for: Claude Code, Codex.

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 696 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00044 $0.00696
Opus 5 $0.00022 $0.00348
Sonnet 5 $0.00009 $0.00139
Haiku 4.5 $0.00004 $0.00070

Measured 2d ago against content hash bd4286cbd2ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

design-patterns 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 2d 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.

.agents/skills/design-patterns/SKILL.md · 62 lines

How it starts

The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Design Patterns GoF in Delphi — Skill

Use this skill when the user requests implementation of design patterns in Delphi. Always apply together with naming conventions (T/I/E/F/A/L) and memory management (try..finally).

When to Use

  • Create Factory, Abstract Factory or Builder for creating complex objects
  • Implement Strategy to vary algorithms (calculation of freight, taxes, export)
  • Use Observer for decoupled notifications (Domain Events)
  • Apply Command for undo/redo, job queues or auditing
  • Use Decorator to add responsibilities without inheritance
  • Implement Adapter for integration with legacy systems
  • Use Facade to simplify complex subsystems (e.g. NFe emission)
  • Apply Template Method to algorithms with variations (reports, exports)
  • Use State for behavior that changes depending on the state of the object
  • Use Chain of Responsibility for validation or processing pipelines

📌 Guide to Choosing the Right Pattern

Need Standard Category
Create objects with type variation Factory Method / Abstract Factory Creational
Create complex objects step by step Builder Creational
Ensure Global Single Instance Singleton Creational
Copy objects Prototype Creational
Adapt incompatible interface Adapter Structural
Add responsibilities dynamically Decorator Structural
Simplify complex system Facade Structural
Control access to an object Proxy Structural
Compose objects in tree structure Composite Structural
Vary algorithm without changing context Strategy Behavioral
Notify multiple objects about changes Observer Behavioral
Encapsulate actions with undo/redo Command Behavioral
Algorithm with variations Template Method Behavioral
Pass request through handler chain Chain of Responsibility Behavioral
Behavior that changes with the state State Behavioral

Full implementation and code for each pattern is in the reference files below — read the one matching the category the task needs rather than guessing.

Read the full file on GitHub · 62 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

  1. 2d ago First seen · 62 lines · 44 tokens per session scan A bd4286cbd2ef

Subscribe to this mod's changes

design-patterns is a skill published in the GitHub repository SecondLifes/delphi-expert (3 stars, last pushed 22d ago), licensed MIT. It adds 44 tokens to every session and 696 once invoked, about $0.0002 per session on Opus 5. 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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