Strategy Pattern (Symfony)
Use when
- One operation has several interchangeable algorithms chosen at runtime, such as payment providers or export formats.
- A
switch or match on a type string keeps growing.
- New variants must be added without editing the code that selects them.
Default workflow
- Define the strategy interface, with a
supports() method or a key per strategy.
- Tag every implementation through
#[AutoconfigureTag] on the interface or on each class.
- Inject them with
#[AutowireIterator] to try each in order, or #[AutowireLocator] to fetch one by key.
- Set priorities where evaluation order matters, and register a fallback strategy.
- Test each strategy alone, and the selector with fakes.
Guardrails
- The selector fails explicitly when no strategy supports the input.
- Keep strategies stateless and independent of each other.
- Two cases that will not grow do not need the pattern: a
match is enough.
Progressive disclosure
- Use this file for execution posture and risk controls.
- Open references when deep implementation details are needed.
Output contract
- The interface and its tagged implementations.
- The selector, with its order and its fallback.
- Tests per strategy and for the no-match case.
References
