--- title: Clean code tip: Principle of Least Surprise | daily.dev description: The Principle of Least Surprise (or Least Astonishment) states that a function or class should behave exactly as its name suggests, with no hidden side... canonical: https://daily.dev/posts/clean-code-tip-principle-of-least-surprise-dpbbwo0q3 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Clean code tip: Principle of Least Surprise | daily.dev og:description: The Principle of Least Surprise (or Least Astonishment) states that a function or class should behave exactly as its name suggests, with no hidden side... og:url: https://daily.dev/posts/clean-code-tip-principle-of-least-surprise-dpbbwo0q3 og:image: https://api.daily.dev/og/posts/DpBbWO0q3.png og:image:alt: Clean code tip: Principle of Least Surprise og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Clean code tip: Principle of Least Surprise **[Code4IT](https://daily.dev/sources/code4it)** · 3 min read · 0 upvotes · 0 comments ## Summary The Principle of Least Surprise (or Least Astonishment) states that a function or class should behave exactly as its name suggests, with no hidden side effects. Examples in C# illustrate a Concatenate method that silently lowercases output, an InsertItem method that secretly updates existing records, and a class named RepositoryFactory that actually implements a Singleton pattern instead. The fix in each case is choosing clearer, more honest names like ConcatenateInLowerCase, InsertOrUpdate/Upsert, and naming classes after the pattern they actually implement. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Refactoring with Convergence Rules](https://daily.dev/posts/refactoring-with-convergence-rules-6ofmsa39f) · Ruby Flow · 0 upvotes · 0 comments - [DRY Is the Most Misunderstood Rule in Programming](https://daily.dev/posts/dry-is-the-most-misunderstood-rule-in-programming-ithr21mpi) · Milan Jovanović · 11 upvotes · 0 comments - [Abstraction Is Not Merely Hiding Complex Code](https://daily.dev/posts/abstraction-is-not-merely-hiding-complex-code-tvfkgxuc9) · Medium · 0 upvotes · 1 comments - [You're Not Building Netflix: Stop Coding Like You Are](https://daily.dev/posts/you-re-not-building-netflix-stop-coding-like-you-are-fvaumfnpy) · DEV · 673 upvotes · 55 comments --- Tags: [#general-programming](https://daily.dev/tags/general-programming), [#c#](https://daily.dev/tags/c#), [#design-patterns](https://daily.dev/tags/design-patterns) [View this post on daily.dev](https://daily.dev/posts/clean-code-tip-principle-of-least-surprise-dpbbwo0q3) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Clean code tip: Principle of Least Surprise","url":"https://daily.dev/posts/clean-code-tip-principle-of-least-surprise-dpbbwo0q3","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/clean-code-tip-principle-of-least-surprise-dpbbwo0q3"},"datePublished":"2026-10-04T13:07:33.966Z","dateModified":"2026-10-04T13:17:53.120Z","description":"The Principle of Least Surprise (or Least Astonishment) states that a function or class should behave exactly as its name suggests, with no hidden side...","image":"https://media.daily.dev/image/upload/s--OHB84bZF--/f_auto/v1722860399/public/Placeholder%2010","thumbnailUrl":"https://media.daily.dev/image/upload/s--OHB84bZF--/f_auto/v1722860399/public/Placeholder%2010","isAccessibleForFree":true,"articleSection":"Code4IT","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Code4IT","logo":"https://media.daily.dev/image/upload/s--OaaG4G10--/f_auto,q_auto/v1791119049/logos/code4it?_a=BAMAMicg0","url":"https://daily.dev/sources/code4it"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/clean-code-tip-principle-of-least-surprise-dpbbwo0q3","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"general-programming,c#,design-patterns","timeRequired":"PT3M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Code4IT","item":"https://daily.dev/sources/code4it"},{"@type":"ListItem","position":3,"name":"Clean code tip: Principle of Least Surprise"}]} ```