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Principles

Error handling

Let failures reach the code that can handle them, without every caller checking.

Pick your language

Error handling: replace error codes with exceptions in Kotlin, step 2: Freeze accountsKotlin · ~6 minError handling in KotlinError handling: replace error codes with exceptions in C++, step 2: Freeze accountsC++ · ~5 minError handling in C++Error handling: replace error codes with exceptions in Ruby, step 2: Freeze accountsRuby · ~5 minError handling in RubyError handling: replace error codes with exceptions in Go, step 2: Freeze accountsGo · ~5 minError handling in GoError handling: replace error codes with exceptions in Rust, step 2: Freeze accountsRust · ~5 minError handling in RustError handling: replace error codes with exceptions in Swift, step 2: Freeze accountsSwift · ~6 minError handling in Swift

When to use it

Use it when

A failure starts deep in a call chain, and only a caller near the top knows how to answer it.

Skip it when

The direct caller answers the failure, like a lookup that often finds nothing. No chain to skip, so a nullable result and an elvis do it. Distance decides, not rarity.

Spot it by

Constants like minus one for failure, if (code != OK) return code passed up the chain, or an else branch that treats unknown codes as success.