Strategy Pattern

🚀Strategy Pattern

Contributor Extension Point

Keep tag generation, existing-tag ordering, and cross-format conversion as separate responsibilities.

Commandapp/core/git_ops/tag_strategy/

📦Category

Architecture

🚀Quick Command

requested strategy -> implementation -> version tag

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TagStrategyTagSorterfactoryVersionBridge

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🏷️

Generation Contract

TagStrategy

⚙️

Generation Choices

5

📋

Sorting Contract

TagSorter

🕒

Sorting Choices

4

Overview

Custy uses two related but independent strategy families. A TagStrategy calculates a new tag. A TagSorter orders tags that already exist. Keeping the families separate prevents parsing and ordering rules from becoming mixed with version-bump policy.

VersionBridge is a supporting conversion utility. It synchronizes equivalent SemVer and PEP 440 representations when a project file requires a different format from the selected Git tag; it does not choose the next version.

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The Three Responsibilities

Generate a Tag

Sort Existing Tags

Convert a Version

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Tag Generation Family

🏗️Built-in Tag Strategies

These implementations answer one question: what tag should Custy use next?

Pattern	Purpose	Implementation
SemVer	Increment a semantic version using the selected bump and optional prerelease input.	SemverStrategy
PEP 440	Generate a Python-compatible public version from repository state and bump input.	PEP440Strategy
Commitizen	Use Commitizen-compatible project metadata, then delegate the version calculation through semantic-version behavior.	CommitizenStrategy
Date	Create a date-based tag for projects whose releases are organized by calendar value.	DateStrategy
Git Count	Derive the next value from repository commit count.	GitCountStrategy

ℹ️An explicit tag has highest priority

When the caller supplies a tag directly, WorkflowEngine stores that value instead of invoking a generation strategy. The strategy setting matters only when Custy must calculate the next tag.

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🔄Tag Resolution Flow

🕒Workflow Timeline

1

Resolve CLI and configuration

The command resolver prepares the explicit tag, strategy, bump, prerelease, and related inputs.

completed

2

Build WorkflowConfig

WorkflowEngineBuilder carries the resolved values into one engine configuration.

completed

3

Check explicit input

A supplied tag is accepted directly and bypasses automatic generation.

completed

4

Select implementation

Without an explicit tag, WorkflowEngine dispatches to the concrete strategy for the selected enum value.

current

5

Generate the value

The strategy reads only the repository or project inputs it needs and returns the next tag string.

pending

6

Apply and consume

Later workflow phases update version files, generate changelog context, create the Git tag, and optionally push it.

pending

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Tag Sorting Family

📦Existing-Tag Ordering

GitService→TagSorterFactory

Requests a sorter that matches the active version strategy.

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TagSorterFactory→SemverSorter

Orders semantic-version tags.

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TagSorterFactory→PEP440Sorter

Orders PEP 440-compatible tags.

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TagSorterFactory→DateSorter

Orders date-based tags.

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TagSorterFactory→GitCountSorter

Orders commit-count tags.

GitService detects or receives a project strategy, creates the matching sorter, and caches it for later tag queries. Commitizen does not have a separate sorter: its generated versions use semantic-version behavior, so compatible tags are ordered through the SemVer path.

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Extension Boundary

Adding a source-owned generation strategy requires more than implementing get_next_tag(). The contributor must also extend the strategy choice enum, workflow dispatch, CLI and configuration resolution, tests, and documentation. If the resulting tag format needs special ordering, the sorter family and factory require a corresponding implementation too.

⚠️This is not a public plugin contract

The protocols make internal code easier to extend and test, but Custy does not currently discover or install third-party strategy plugins at runtime.

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Continue

🚀Related Commands

Commands commonly used together with this command.

Git Operations

See where existing tags are read, sorted, created, and pushed.

Workflow Engine

Inspect the active dispatch and downstream release phases.

Versioning Concept

Compare strategies, version-file formats, and user-facing behavior.

Adding Version Strategies

Follow the complete contributor checklist for a new implementation.