Extract method refactoring

Extract method refactoring moves a coherent chunk of operations into a separately named method so the caller reads as a clearer story. The extracted name should reveal the chunk’s purpose, reducing the decoding work required of a reader. section 2.3.5

if (isEligible(user)) { ... }

A complex eligibility condition becomes a single named question. The caller can focus on the decision instead of reconstructing its Boolean details. section 2.3.5

Extract when code becomes cognitively heavy: a long method, deep nesting, a complex or repeated expression, or a group of operations that expresses one business concept. Extraction also helps keep a caller at a uniform level of abstraction. A method name that remains hard to choose is a signal that the chunk may contain more than one responsibility. section 2.3.5 section 2.5

Use the size and role of a chunk to decide where a method boundary belongs:

• Keep an action-level method narrow: it performs a low-level operation such as validating one field. section 2.3.5 section 2.5
• Build a scene-level method from actions and modest supporting logic, such as a small number of conditionals, a loop, or error handling. section 2.5
• Let the original, chapter-level method coordinate scene-level methods into the main flow. section 2.5

 if (isUserEligible(user)) { 
        handleUserPermissions(user);        
 }

Moving nested permission handling behind a purpose-revealing call flattens the visible control flow. The outer method states the main decision; the helper owns the detailed branch. section 2.3.5

Do not extract mechanically. Leave code in place when the caller is already short, readable, and at one level of abstraction; when the new method would merely wrap one simple chunk; or when it would not improve readability. Extraction is most valuable in complex business logic, maintainability-focused work, and legacy code, but may be unnecessary for simple logic, prototypes, or performance-critical low-level sections. section 2.5

A useful heuristic is simple: extract a method when its name makes the caller easier to understand. The result should expose the main story while leaving each helper responsible for one recognizable step. section 2.3.5 section 2.5