CODEWITHSUNDEEP
flutterdartsyntax
Koorb Notsyor
Koorb Notsyor

Reputation: 5

Flutter use of variable <T> : context.read() instead of context<T>.read()

I consistently see code such as the following in Flutter example code:

sharedPreferencesService: context.read()

I understand that this must be a syntactical shortcut for

sharedPreferencesService: context<SharedPreferenceService>.read(),

Where is this feature of Dart documented?

Upvotes: 0

Views: 40

Answers (2)

Mahmoud Vakili
Mahmoud Vakili

Reputation: 26

This feature is made possible by extension methods in Dart, which were introduced in version 2.7. In packages like provider, an extension method (for example, read()) is defined on the BuildContext. This allows you to use a syntax like:

sharedPreferencesService: context.read()

This is essentially a syntactical shortcut where the generic type is inferred, similar to explicitly writing:

sharedPreferencesService: context.read<SharedPreferenceService>()

For more detailed information, you can refer to the following documentation: Extension Methods – Dart Language Tour Generics – Dart Language Tour

Upvotes: 0

Reza Farjam
Reza Farjam

Reputation: 1105

It is called type inference in the Dart language.

What’s happening here is that the analyzer can infer the type of the generic based on the parameter type.

You can find more examples and explanations about it here:
https://dart.dev/language/type-system#type-inference

Upvotes: 0

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