Crystal is a programming language with Ruby-like syntax and static type checking. It aims to have the elegance and productivity of Ruby combined with the speed, efficiency, and type safety of a compiled language.
Crystal Anti-Patterns Overview
Crystal, despite being a modern language with many safeguards, has several common anti-patterns that can lead to performance issues, maintainability problems, and bugs. Here are the most important anti-patterns to avoid when writing Crystal code.
Not Leveraging the Type System
Leverage Crystal’s type system instead of using generic Object types. Use union types, generics, and type restrictions to make your code more type-safe and efficient. This helps catch errors at compile time rather than runtime.
Using Exceptions for Control Flow
Avoid using exceptions for normal control flow. Exceptions should be reserved for exceptional conditions. Instead, use nil or Result types to represent the possibility of failure in a type-safe way.
Not Using Proper Nil Handling
Use proper nil handling techniques like the safe navigation operator (&.
), nil checks, or the try
method. This makes your code more robust and prevents nil-related runtime errors.
Mutable Global State
Avoid using mutable global state. Global variables make code harder to reason about, test, and maintain. Instead, use dependency injection, class variables with controlled access, or dedicated configuration objects.
Not Using Named Arguments for Clarity
Use named arguments for methods with many parameters or boolean flags. This makes your code more readable and less prone to errors from mixing up argument order.
Inefficient String Concatenation
Avoid inefficient string concatenation in loops. Instead, use String.build
, array joining, or string interpolation for better performance and readability.
Not Using Crystal's Concurrency Features Properly
Use Crystal’s concurrency features properly. When using fibers with spawn
, ensure proper synchronization for shared resources using channels, mutexes, or other synchronization primitives.
Not Using Proper Error Handling
Implement proper error handling in your code. Don’t ignore exceptions; catch and handle them appropriately. Use specific rescue clauses for different error types to provide better error messages and recovery strategies.
Not Using Crystal's Standard Library
Leverage Crystal’s rich standard library instead of reinventing the wheel. The standard library provides efficient, well-tested implementations for common tasks like JSON parsing, HTTP requests, file I/O, and more.
Not Using Type Annotations When Helpful
Add type annotations to method signatures when it helps with clarity, especially for public APIs. While Crystal can often infer types, explicit annotations make your code more self-documenting and can catch type errors earlier.
Not Using Proper Abstractions
Use proper abstractions like modules, inheritance, and generics to avoid code duplication. This makes your code more maintainable and extensible.
Not Using Proper Immutability
Consider using immutability for your data structures when appropriate. Immutable objects are easier to reason about, especially in concurrent contexts. Use methods that return new instances instead of modifying existing ones.
Not Using Proper Enums
Use enums for fixed sets of related values instead of strings or integers. Enums provide type safety, better documentation, and prevent invalid values.
Not Using Proper Macros
Use macros judiciously. While Crystal’s macro system is powerful, overusing macros can make code harder to understand and debug. Use simpler constructs like methods, constants, or classes when they suffice, and reserve macros for cases where metaprogramming is truly needed.
Not Using Proper Testing
Write comprehensive tests for your code. Crystal’s spec framework makes it easy to write and run tests. Test different scenarios, edge cases, and error conditions to ensure your code works correctly in all situations.
Not Using Proper Documentation
Document your code properly, especially public APIs. Include descriptions of classes, methods, parameters, return values, and any exceptions that might be raised. Good documentation makes your code more accessible to others and to your future self.
Not Using Proper Resource Management
Use proper resource management techniques. When working with resources like files, database connections, or network sockets, use blocks that automatically handle closing the resource, or ensure you close them manually in a begin
/ensure
block.