defensive-programming-framework

import { cannotBeNull, mustBeGreaterThanOrEqualTo, whenIsNull, whenIsLessThan, ArgumentError } from 'defensive-programming-framework'; /** * Example function demonstrating defensive programming with the framework. * Validates and potentially corrects input parameters. */ export function write(buffer: number[], startIndex: number, data: number[]): void { // Unconditional validation - throws ArgumentError on failure cannotBeNull(buffer); // Throws if buffer is null cannotBeNull(data); // Throws if data is null // Corrective validation - attempts to fix input, returns corrected value // If startIndex is less than 0, it's corrected to 0. startIndex = whenIsLessThan(startIndex, 0, 0); // If data is null, it's corrected to an empty array. data = whenIsNull(data, []); // Mixed validation - ensuring corrected values meet further conditions mustBeGreaterThanOrEqualTo(startIndex, 0); // Re-validate startIndex (now guaranteed >= 0 if corrected) // Custom conditional check (can be wrapped in a framework function if frequently used) if (data.length >= buffer.length - startIndex) { throw new ArgumentError(`Length of data cannot be greater than remaining buffer space (${buffer.length - startIndex}).`); } console.log('Validation passed. Proceeding with actual write operation...'); // Actual execution code would go here // For demonstration, let's just log the validated inputs console.log('Buffer:', buffer); console.log('StartIndex:', startIndex); console.log('Data:', data); } // Example usage: try { console.log('\n--- Valid Case ---'); write([1, 2, 3, 4, 5], 1, [10, 20]); // Valid inputs console.log('\n--- Corrective Case ---'); write([1, 2, 3, 4, 5], -5, null); // startIndex corrected to 0, data corrected to [] console.log('\n--- Error Case ---'); write([1, 2], 0, [10, 20, 30]); // Data length too large for buffer } catch (e) { if (e instanceof ArgumentError) { console.error('Validation Error (caught):', e.message); } else { console.error('Unexpected Error (caught):', e); } }