Ruby / Contracts: callables, evaluation, failures, and value models

Ruby β€” Contracts: callables, evaluation, failures, and value models

Use callbacks, Enumerable, exceptions, mixins, Data/Struct, and patterns without hidden lifetime or validation assumptions.

6 lessons Β· No account required

What you will learn

  • Preserve data meaning and behavior across reusable method and model boundaries.

  1. Control block, Proc, and lambda lifetimes

    Read closure capture, argument handling, non-local return, and synchronous invocation before storing or reusing callbacks.

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  2. Build Enumerable pipelines with deliberate evaluation

    Use selection, mapping, grouping, aggregation, and lazy enumeration while preserving false values, bounded work, and effect ownership.

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  3. Translate exceptions without hiding failures

    Use narrow rescue clauses, explicit rejection, preserved causes, and ensure cleanup while keeping successful data distinct from fallback.

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  4. Compose modules through a visible method lookup contract

    Distinguish namespaces, include, extend, prepend, and super while avoiding broad monkey patches and hidden lifecycle changes.

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  5. Choose Data or Struct with explicit value semantics

    Understand generated members, shallow value objects, with copies, eql?/hash contracts, and stable collection keys.

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  6. Match structured data without overclaiming validation

    Use case/in, type and hash patterns, guards, pins, and explicit mismatch policy under the selected Ruby 3.3 baseline.

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