Laziness and magic bring defects
TL;DR: Be explicit with your attributes
Problems
Readability
Scope definition
Unnoticed typos
Solutions
- Favor languages forbidding dynamic properties
Context
Dynamic properties break type safety since it's easy to introduce typos or use the wrong property names accidentally.
This can lead to runtime errors that can be difficult to debug, especially in larger codebases.
They also hide possible name collisions since dynamic properties may have the same name as properties defined in the class or object, leading to conflicts or unexpected behavior.
Sample Code
Wrong
class Dream:
pass
nightmare = Dream()
nightmare.presentation = "I am the Sandman"
# presentation is not defined
# it is a dynamic property
print(nightmare.presentation)
# Output: "I am the Sandman"
Right
class Dream:
def __init__(self):
self.presentation = None
nightmare = Dream()
nightmare.presentation = "I am the Sandman"
print(nightmare.presentation)
# Output: "I am the Sandman"
Detection
[X] Automatic
Most languages have compiler options to avoid them.
Tags
- Metaprogramming
Conclusion
Dynamic properties are supported in many programming languages like PHP, Python, Ruby, JavaScript, C#, Objective-C, Swift, Kotlin, etc.
In these languages, dynamic properties can be added to objects at runtime, and accessed using the object's property accessor syntax.
Bear in mind that having public attributes favors Anemic Objects which is another smell.
Relations
Disclaimer
Code Smells are my opinion.
Credits
Photo by Karsten Würth on Unsplash
It's easy to cry "bug" when the truth is that you've got a complex system and sometimes it takes a while to get all the components to co-exist peacefully.
D. Vargas
This article is part of the CodeSmell Series.
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