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Discussion on: Are there things you see in others' code that just automatically makes you twitch/shudder

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sebbdk profile image
Sebastian Vargr

The i' infront of interface names some people add.

WHY. JEBUS. BRIST...just!... no!.. please?

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Carson Sturtevant

Can you share why you dislike that so much? I've seen it many times and thought it was the standard.

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sebbdk profile image
Sebastian Vargr • Edited on

Exactly, everyone think it’s the standard.
But very few really know why. :)

The i’ is not needed because you are denoting a subject type, like horse.

The actual class implementing class will always be a subtype with a more specific name like FastHorse, or IcelandicLeperHorse or some such.

If we actually had a horse’ class, then we would not really need a horse interface, because we would not have subtypes.

This makes the i’ entirely redundant, since interfaces serve like a type, similar to how variables and classes do.

I mean you would not prepend a number variable with n’ would you?

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sebbdk profile image
Sebastian Vargr

Counter argument here would be that sometimes knowing the structure type is practical, like if you are using inflection.

But inflection is bad, and again it’s a specific usecase. So making it a global rule’ is kinda overkill.

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Carson Sturtevant • Edited on

Interesting. I've seen the interface match the class when its a service. ex. IDataService and DataService. The 'I' is used to distinguish between the 2 files easily. The interface is needed for dependency injection.

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sebbdk profile image
Sebastian Vargr

I have seen that argument somewhere before, but i still wonder.
Would the class definition not suffice as the type?

I mean dependency injection systems usually just manage shared instances.

Maybe it's language dependent and i am just missing a piece of the puzzle. :/

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Abhinav Kulshreshtha

It's not standard, Hungarian notation was used back in the days when programming languages were very low level and IDE's were not a thing. It made a comeback these days because People wrongly assumed it was coding standard for android. Because people are more focused on coding than architectural understanding.

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Rachel Soderberg

I didn't know this was a bad thing! I was taught it in college a couple of years back when we covered design patterns...

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Abhinav Kulshreshtha

I hate them too. I have seen new typescript demos using it and I think it's stupid. I also don't like how some newer programming languages allows you to write implementation code in interfaces( looking at you kotlin ) . Interface should be used to only define structures. Implementations should be left to whatever implements it as the name suggests.