Terms starting with "C"
CQRS Pattern
PHP 7.0+
1
Command Query Responsibility Segregation — separating the write model (commands that change state) from the read model (queries that return data), allowing each to be optimised independently.
6mo ago
Messaging advanced
CRDTs — Conflict-Free Replicated Data Types
Data structures designed to be replicated across multiple nodes where concurrent updates are automatically merged without conflicts — no coordination or consensus required, enabling high availability with eventual consistency.
6mo ago
Architecture advanced
create_function() — The Dynamic Code Smell
PHP 4.0+
8
create_function() created anonymous functions from strings — deprecated PHP 7.2, removed PHP 8. It used eval() internally, risked code injection, and was always replaceable with proper closures.
6mo ago
PHP intermediate
Cross-Version Compatibility Testing
PHP 7.0+
Testing PHP code across multiple versions uses CI matrix builds, phpenv/phpbrew, Docker multi-version setups, and static analysis to catch compatibility issues before deployment.
6mo ago
PHP intermediate
CSS :has() Selector
CSS :has() is a parent selector — .card:has(.badge) matches a .card that contains a .badge — enabling styles that depend on children or siblings, which previously required JavaScript.
6mo ago
Frontend intermediate
CSS Nesting (Native)
Native CSS nesting lets you write nested selectors directly in CSS without a preprocessor — &:hover inside .card applies to .card:hover — available in all modern browsers since 2023 without any build step.
6mo ago
Frontend beginner
Call to Undefined Function/Method
PHP 4.0+
1
'Call to undefined function' means the function wasn't declared, the file wasn't loaded, or the PHP extension providing it isn't installed.
6mo ago
PHP beginner
callable vs Closure vs First-Class Callable
PHP 7.1+
PHP has three callable forms: loose callable (string/array), typed Closure, and PHP 8.1 first-class callables (strlen(...)) — prefer Closure or first-class callables for type safety.
6mo ago
PHP intermediate
Cannot Redeclare Function/Class Errors
PHP 4.0+
PHP throws a fatal error when a function or class is declared twice in the same request — use autoloading and function_exists() guards to prevent it.
6mo ago
PHP beginner
Circular References & Memory Implications
PHP 5.3+
1
Circular references between objects prevent PHP's reference counting GC from freeing memory — PHP's cycle collector handles them but with overhead.
6mo ago
PHP intermediate
Class Not Found / Autoloader Failures
PHP 5.3+
'Class not found' errors mean the autoloader couldn't locate the class file — usually a namespace mismatch, missing composer install, or PSR-4 misconfiguration.
6mo ago
PHP beginner
Classic Closure-in-Loop Bug (var vs let)
ES2015
The most common JavaScript closure bug: using var in a for loop captures the loop variable by reference so all callbacks see the final value — fixed by using let which creates a new binding per iteration.
6mo ago
JavaScript intermediate
Constructor Promotion + readonly Together
PHP 8.1+
PHP 8.1+ allows readonly in constructor promotion: public function __construct(public readonly string $name) — the cleanest way to write immutable value objects.
6mo ago
PHP intermediate
Custom Error Handlers (set_error_handler)
PHP 5.0+
2
set_error_handler() lets you replace PHP's default error handling with a custom callback — essential for logging, alerting, and graceful degradation.
6mo ago
PHP intermediate
Client-Side Sanitisation
ES2015
5
DOMPurify and the Sanitizer API remove dangerous HTML before insertion — complementing PHP's server-side htmlspecialchars for rich-text scenarios.
6mo ago
JavaScript intermediate
CSRF Token Handling in Fetch & Axios
ES2017
Including PHP-generated CSRF tokens in JavaScript requests — reading from meta tags or cookies and attaching to every state-changing request.
6mo ago
JavaScript intermediate
Cache Warming Strategies
PHP 5.0+
Pre-populating a cache before traffic arrives — preventing the cold-start thundering herd where every request misses a cold cache simultaneously after a deploy.
6mo ago
Performance intermediate
Cache-Timing Side-Channel Attacks
PHP 5.6+
Attacks that infer secret information from response time differences — cached responses arrive faster than uncached ones, leaking whether a resource exists or a secret was correct.
6mo ago
Security advanced
Certificate Transparency Logs
1
Public append-only logs of all issued TLS certificates — enabling detection of misissuance and rogue certificates within hours rather than months.
6mo ago
Cryptography advanced
Character Encoding
PHP 5.0+
3
How text is stored as bytes — ASCII (128 chars), Latin-1 (256 chars), UTF-8 (1-4 bytes, backwards compatible), and UTF-16 are the key encodings developers encounter.
6mo ago
i18n intermediate