Maxi Contieri
@maximilianocontieri.com
🎓Learn something new every day.📆
💻CS software engineer / Book Author
http://MaximilianoContieri.com
http://CleanCodeCookbook.com
💻CS software engineer / Book Author
http://MaximilianoContieri.com
http://CleanCodeCookbook.com
Refactoring 034 - Reify Parameters
Turn scattered inputs into one clear object
maximilianocontieri.com
October 7, 2025 at 12:53 PM
Refactor with AI 🤖
Ask AI to scan your codebase for functions that use two or more parameters of the same type.
Instruct it to propose an entity name, generate the type or class, and rewrite both the function and its callers to use the new entity.
Ask AI to scan your codebase for functions that use two or more parameters of the same type.
Instruct it to propose an entity name, generate the type or class, and rewrite both the function and its callers to use the new entity.
October 7, 2025 at 12:53 PM
Refactor with AI 🤖
Ask AI to scan your codebase for functions that use two or more parameters of the same type.
Instruct it to propose an entity name, generate the type or class, and rewrite both the function and its callers to use the new entity.
Ask AI to scan your codebase for functions that use two or more parameters of the same type.
Instruct it to propose an entity name, generate the type or class, and rewrite both the function and its callers to use the new entity.
When you ask someone to "search for products with a minimum price of 50 and a maximum price of 100," you use named concepts.
This refactoring mirrors that natural [language structure](maximilianocontieri.com/what-is-wron...) in your code.
This refactoring mirrors that natural [language structure](maximilianocontieri.com/what-is-wron...) in your code.
What is (wrong with) software?
Software is eating the world. Those of us who work, live, and love software do not usually stop by to think about its meaning. TL:DR: We will address current software design problems in a minimalist way. In university and industry, we use the follo...
maximilianocontieri.com
October 7, 2025 at 12:53 PM
When you ask someone to "search for products with a minimum price of 50 and a maximum price of 100," you use named concepts.
This refactoring mirrors that natural [language structure](maximilianocontieri.com/what-is-wron...) in your code.
This refactoring mirrors that natural [language structure](maximilianocontieri.com/what-is-wron...) in your code.
You stop treating the data as loose numbers and give them an [explicit identity](maximilianocontieri.com/code-smell-0...) that matches the domain.
In the real world, you describe searches using named criteria rather than ordered lists.
In the real world, you describe searches using named criteria rather than ordered lists.
Code Smell 01 - Anemic Models
Anemic Objects are a very common smell treating objects as data structures with few or missing behavior
maximilianocontieri.com
October 7, 2025 at 12:53 PM
You stop treating the data as loose numbers and give them an [explicit identity](maximilianocontieri.com/code-smell-0...) that matches the domain.
In the real world, you describe searches using named criteria rather than ordered lists.
In the real world, you describe searches using named criteria rather than ordered lists.
How Does it Improve the Bijection? 🗺️
You move closer to a [one-to-one map](maximilianocontieri.com/what-is-wron...) between the business concept of a "search request" and your code model.
You move closer to a [one-to-one map](maximilianocontieri.com/what-is-wron...) between the business concept of a "search request" and your code model.
What is (wrong with) software?
Software is eating the world. Those of us who work, live, and love software do not usually stop by to think about its meaning. TL:DR: We will address current software design problems in a minimalist way. In university and industry, we use the follo...
maximilianocontieri.com
October 7, 2025 at 12:53 PM
How Does it Improve the Bijection? 🗺️
You move closer to a [one-to-one map](maximilianocontieri.com/what-is-wron...) between the business concept of a "search request" and your code model.
You move closer to a [one-to-one map](maximilianocontieri.com/what-is-wron...) between the business concept of a "search request" and your code model.
You enable better IDE support with autocomplete showing parameter names.
You create opportunities to [reuse the parameter object type](maximilianocontieri.com/code-smell-1...) across related functions.
You create opportunities to [reuse the parameter object type](maximilianocontieri.com/code-smell-1...) across related functions.
Code Smell 194 - Missing Interval
From date should be lower than to date
maximilianocontieri.com
October 7, 2025 at 12:53 PM
You enable better IDE support with autocomplete showing parameter names.
You create opportunities to [reuse the parameter object type](maximilianocontieri.com/code-smell-1...) across related functions.
You create opportunities to [reuse the parameter object type](maximilianocontieri.com/code-smell-1...) across related functions.
You eliminate the risk of passing arguments in the wrong order since the object properties have explicit names.
You make function calls self-documenting because each value clearly indicates its purpose.
You simplify adding new optional parameters without breaking existing code.
You make function calls self-documenting because each value clearly indicates its purpose.
You simplify adding new optional parameters without breaking existing code.
October 7, 2025 at 12:53 PM
You eliminate the risk of passing arguments in the wrong order since the object properties have explicit names.
You make function calls self-documenting because each value clearly indicates its purpose.
You simplify adding new optional parameters without breaking existing code.
You make function calls self-documenting because each value clearly indicates its purpose.
You simplify adding new optional parameters without breaking existing code.
Why is the Code Better? ✨
You avoid order confusion and increase readability.
You make functions easy to extend with new parameters.
You bring semantic meaning to the input data.
You avoid order confusion and increase readability.
You make functions easy to extend with new parameters.
You bring semantic meaning to the input data.
October 7, 2025 at 12:53 PM
Why is the Code Better? ✨
You avoid order confusion and increase readability.
You make functions easy to extend with new parameters.
You bring semantic meaning to the input data.
You avoid order confusion and increase readability.
You make functions easy to extend with new parameters.
You bring semantic meaning to the input data.
Steps 👣
1. Identify multiple parameters of the same type
2. Create a meaningful entity to group them
3. Add missing validation rules to fail fast
4. Replace function signatures with the new entity
5. Adjust all callers to pass the entity
6. Add context-specific names to improve clarity
1. Identify multiple parameters of the same type
2. Create a meaningful entity to group them
3. Add missing validation rules to fail fast
4. Replace function signatures with the new entity
5. Adjust all callers to pass the entity
6. Add context-specific names to improve clarity
October 7, 2025 at 12:53 PM
Steps 👣
1. Identify multiple parameters of the same type
2. Create a meaningful entity to group them
3. Add missing validation rules to fail fast
4. Replace function signatures with the new entity
5. Adjust all callers to pass the entity
6. Add context-specific names to improve clarity
1. Identify multiple parameters of the same type
2. Create a meaningful entity to group them
3. Add missing validation rules to fail fast
4. Replace function signatures with the new entity
5. Adjust all callers to pass the entity
6. Add context-specific names to improve clarity
[Code Smell 93 - Send me Anything](maximilianocontieri.com/code-smell-9...)
[Code Smell 122 - Primitive Obsession](maximilianocontieri.com/code-smell-1...)
[Code Smell 122 - Primitive Obsession](maximilianocontieri.com/code-smell-1...)
Code Smell 93 - Send me Anything
Magic functions that can receive a lot of different (and not polymorphic arguments) TL;DR: Create a clear contract. Expect just one protocol. Problems Fail Fast principle violation Error prune Readability If polluting Nulls Bad Cohesion Sol...
maximilianocontieri.com
October 7, 2025 at 12:53 PM
[Code Smell 93 - Send me Anything](maximilianocontieri.com/code-smell-9...)
[Code Smell 122 - Primitive Obsession](maximilianocontieri.com/code-smell-1...)
[Code Smell 122 - Primitive Obsession](maximilianocontieri.com/code-smell-1...)
[Code Smell 01 - Anemic Models](maximilianocontieri.com/code-smell-0...)
[Code Smell 188 - Redundant Parameter Names](maximilianocontieri.com/code-smell-1...)
[Code Smell 188 - Redundant Parameter Names](maximilianocontieri.com/code-smell-1...)
Code Smell 01 - Anemic Models
Anemic Objects are a very common smell treating objects as data structures with few or missing behavior
maximilianocontieri.com
October 7, 2025 at 12:53 PM
[Code Smell 01 - Anemic Models](maximilianocontieri.com/code-smell-0...)
[Code Smell 188 - Redundant Parameter Names](maximilianocontieri.com/code-smell-1...)
[Code Smell 188 - Redundant Parameter Names](maximilianocontieri.com/code-smell-1...)
[Code Smell 46 - Repeated Code](maximilianocontieri.com/code-smell-4...)
[Code Smell 143 - Data Clumps](maximilianocontieri.com/code-smell-1...)
[Code Smell 40 - DTOs](maximilianocontieri.com/code-smell-4...)
[Code Smell 143 - Data Clumps](maximilianocontieri.com/code-smell-1...)
[Code Smell 40 - DTOs](maximilianocontieri.com/code-smell-4...)
Code Smell 46 - Repeated Code
DRY is our mantra. Teachers tell us to remove duplication. We need to go beyond. Problems Code Duplication Maintainability Don't Repeat Yourself Solutions Find repeated patterns (not repeated code). Create an abstraction. Parametrize abstract...
maximilianocontieri.com
October 7, 2025 at 12:53 PM
[Code Smell 46 - Repeated Code](maximilianocontieri.com/code-smell-4...)
[Code Smell 143 - Data Clumps](maximilianocontieri.com/code-smell-1...)
[Code Smell 40 - DTOs](maximilianocontieri.com/code-smell-4...)
[Code Smell 143 - Data Clumps](maximilianocontieri.com/code-smell-1...)
[Code Smell 40 - DTOs](maximilianocontieri.com/code-smell-4...)
[Code Smell 177 - Missing Small Objects](maximilianocontieri.com/code-smell-1...)
[Code Smell 194 - Missing Interval](maximilianocontieri.com/code-smell-1...)
[Code Smell 194 - Missing Interval](maximilianocontieri.com/code-smell-1...)
Code Smell 177 - Missing Small Objects
We see small primitive data everywhere
maximilianocontieri.com
October 7, 2025 at 12:53 PM
[Code Smell 177 - Missing Small Objects](maximilianocontieri.com/code-smell-1...)
[Code Smell 194 - Missing Interval](maximilianocontieri.com/code-smell-1...)
[Code Smell 194 - Missing Interval](maximilianocontieri.com/code-smell-1...)
Related Code Smells 💨
[Code Smell 87 - Inconsistent Parameters Sorting](maximilianocontieri.com/code-smell-8...)
[Code Smell 10 - Too Many Arguments](maximilianocontieri.com/code-smell-1...)
[Code Smell 87 - Inconsistent Parameters Sorting](maximilianocontieri.com/code-smell-8...)
[Code Smell 10 - Too Many Arguments](maximilianocontieri.com/code-smell-1...)
Code Smell 87 - Inconsistent Parameters Sorting
Be consistent with parameters sorting to avoid mistakes
maximilianocontieri.com
October 7, 2025 at 12:53 PM
Related Code Smells 💨
[Code Smell 87 - Inconsistent Parameters Sorting](maximilianocontieri.com/code-smell-8...)
[Code Smell 10 - Too Many Arguments](maximilianocontieri.com/code-smell-1...)
[Code Smell 87 - Inconsistent Parameters Sorting](maximilianocontieri.com/code-smell-8...)
[Code Smell 10 - Too Many Arguments](maximilianocontieri.com/code-smell-1...)
- Missing [Small Objects](maximilianocontieri.com/code-smell-1...)
- Missing [Intervals](maximilianocontieri.com/code-smell-1...)
- Missing [Intervals](maximilianocontieri.com/code-smell-1...)
Code Smell 177 - Missing Small Objects
We see small primitive data everywhere
maximilianocontieri.com
October 7, 2025 at 12:53 PM
- Missing [Small Objects](maximilianocontieri.com/code-smell-1...)
- Missing [Intervals](maximilianocontieri.com/code-smell-1...)
- Missing [Intervals](maximilianocontieri.com/code-smell-1...)
- Accidental [argument swapping](maximilianocontieri.com/code-smell-8...)
- [Primitive Obsession](maximilianocontieri.com/code-smell-1...)
- [Data Clumps](maximilianocontieri.com/code-smell-1...)
- Weak type safety
- [Primitive Obsession](maximilianocontieri.com/code-smell-1...)
- [Data Clumps](maximilianocontieri.com/code-smell-1...)
- Weak type safety
Code Smell 87 - Inconsistent Parameters Sorting
Be consistent with parameters sorting to avoid mistakes
maximilianocontieri.com
October 7, 2025 at 12:53 PM
- Accidental [argument swapping](maximilianocontieri.com/code-smell-8...)
- [Primitive Obsession](maximilianocontieri.com/code-smell-1...)
- [Data Clumps](maximilianocontieri.com/code-smell-1...)
- Weak type safety
- [Primitive Obsession](maximilianocontieri.com/code-smell-1...)
- [Data Clumps](maximilianocontieri.com/code-smell-1...)
- Weak type safety
- Low readability
- Hard extension
- [DTOs](maximilianocontieri.com/code-smell-4...)
- Weak semantics
- Repeated [validations](maximilianocontieri.com/code-smell-4...)
- Hard extension
- [DTOs](maximilianocontieri.com/code-smell-4...)
- Weak semantics
- Repeated [validations](maximilianocontieri.com/code-smell-4...)
Code Smell 40 - DTOs
Data Transfer Objects (DTOs) are widely used, and they 'solve' real problems, do they? Problems Anemic Object Inconsistent Data Duplicated logic Duplicated structure Class Polluting Information Hiding Violation Code repeated among mutators, ac...
maximilianocontieri.com
October 7, 2025 at 12:53 PM
- Low readability
- Hard extension
- [DTOs](maximilianocontieri.com/code-smell-4...)
- Weak semantics
- Repeated [validations](maximilianocontieri.com/code-smell-4...)
- Hard extension
- [DTOs](maximilianocontieri.com/code-smell-4...)
- Weak semantics
- Repeated [validations](maximilianocontieri.com/code-smell-4...)
Problems Addressed 😔
- Parameter [overload](maximilianocontieri.com/code-smell-1...)
- [Order confusion](maximilianocontieri.com/code-smell-8...)
- [Anemic Models](maximilianocontieri.com/code-smell-0...)
- Parameter [overload](maximilianocontieri.com/code-smell-1...)
- [Order confusion](maximilianocontieri.com/code-smell-8...)
- [Anemic Models](maximilianocontieri.com/code-smell-0...)
Code Smell 10 - Too Many Arguments
Don't pass more than three arguments to your functions.
maximilianocontieri.com
October 7, 2025 at 12:53 PM
Problems Addressed 😔
- Parameter [overload](maximilianocontieri.com/code-smell-1...)
- [Order confusion](maximilianocontieri.com/code-smell-8...)
- [Anemic Models](maximilianocontieri.com/code-smell-0...)
- Parameter [overload](maximilianocontieri.com/code-smell-1...)
- [Order confusion](maximilianocontieri.com/code-smell-8...)
- [Anemic Models](maximilianocontieri.com/code-smell-0...)