Logos Assembly

03-code-and-comments

3 min read

This document was generated using AI and has yet to be human reviewed

Code & Comments

Implementation Layer — The executable realization of specification requirements

Definition

Code is the executable implementation of a system. Comments are the inline documentation that explains intent, constraints, and non-obvious decisions within that code. Together, they represent the most concrete artifact in the documentation chain.

Relationship to the Specification

Code is where specification requirements become operational. Every function, module, and line of logic should ultimately trace back to some aspect of the specification—whether implementing a required behavior, enforcing a constraint, or providing an interface.

Specification ElementCode Manifestation
Required behaviorFunction or method implementation
ConstraintValidation logic, assertions, guards
Interface definitionAPI signatures, type definitions
State machineControl flow, state variables
Data schemaStructs, classes, database models

The Role of Comments

Comments bridge the gap between what code does (readable from the code itself) and why it does it (requiring context from specification or design decisions).

Effective spec-grounded comments:

// validateMessageSize enforces SPEC-3.4.1: Messages must not exceed 64KB.
// This limit exists to ensure compatibility with legacy relay nodes.
func validateMessageSize(msg []byte) error {
    if len(msg) > 65536 {
        return ErrMessageTooLarge
    }
    return nil
}
/// Implements the handshake protocol per SPEC-2.1.
/// 
/// Note: The 3-second timeout (SPEC-2.1.4) is intentionally short
/// to prevent resource exhaustion under adversarial conditions.
pub async fn perform_handshake(peer: &Peer) -> Result<Session> {
    // ...
}

Dependency Chain

Specification
    ↓
Architecture Docs ← high-level structure
    ↓
Code & Comments ← executable implementation
    ↓
Test Suites ← verify code against spec
    ↓
Contribution Guidelines ← how to modify code correctly

Why Spec-Grounding Matters

Code without specification grounding is just “stuff that runs.” Problems emerge when:

  • Magic numbers: Values appear without explanation; are they arbitrary or mandated by spec?
  • Unexplained logic: Complex code paths exist without rationale; are they implementing requirements or working around bugs?
  • Unsafe refactoring: Developers change code without knowing which specification constraints it enforces
  • Lost intent: As teams change, the reasons behind implementations are forgotten

Anti-Patterns

Comments That Describe What (Useless)

# Increment counter
counter += 1

Comments That Describe Why Without Spec Reference (Better, but Incomplete)

# Prevent overflow
counter += 1

Comments That Ground in Specification (Ideal)

# Per SPEC-7.2: Counter must reset every 2^16 operations to maintain 
# compatibility with 16-bit observers.
counter = (counter + 1) % 65536

Best Practices

  • Reference specification sections in comments for non-obvious constraints
  • Use structured comment formats (@spec, SPEC-X.Y.Z) that tooling can extract
  • Distinguish between spec-mandated behavior and implementation choices
  • Keep spec references up to date when specifications are versioned
  • Consider generating code directly from specification where appropriate (schema compilers, protocol buffers)

Graph View

Backlinks