This content originally appeared on DEV Community and was authored by Areeba Farooq
๐๐ผ๐ ๐๐ฎ๐๐ฒ ๐ฉ๐ฎ๐ฟ๐ถ๐ฎ๐ฏ๐น๐ฒ๐ ๐ฐ๐ฎ๐ป ๐ฏ๐ฒ ๐ฉ๐๐น๐ป๐ฒ๐ฟ๐ฎ๐ฏ๐น๐ฒ?
Instance fields can be initialized in 4 ways:
- At the point of protestation
- In a constructor argument using 'this'
- In the constructorโs initializer list before the law in braces starts.
- Anywhere Differently
4 is problematic since the preface of null safety. By the time the constructor body( the law in braces) starts, the object must be completely initialized so each of its fields are usable. So if it isn't initialized in 1, 2, or 3, it fails to collect.
๐๐ ๐๐๐ง ๐๐ข๐ฑ ๐ญ๐ก๐ข๐ฌ ๐๐ฒ' ๐ฅ๐๐ญ๐' ๐ค๐๐ฒ๐ฐ๐จ๐ซ๐.๐
It literally means โ I'll initialize it latterly โ. And you got no error.
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โ ๏ธ ๐๐ฎ๐ญ ๐ก๐๐ซ๐ ๐๐ซ๐ ๐ญ๐ก๐ ๐ซ๐๐๐ฌ๐จ๐ง๐ฌ ๐ฐ๐ก๐ฒ ๐ฌ๐ก๐จ๐ฎ๐ฅ๐ ๐ฐ๐ ๐ฌ๐ก๐จ๐ฎ๐ฅ๐ ๐๐ฏ๐จ๐ข๐ ๐ฅ๐๐ญ๐ ๐ฏ๐๐ซ๐ข๐๐๐ฅ๐๐ฌ:
๐- ๐๐จ ๐๐จ๐ฆ๐ฉ๐ข๐ฅ๐ - ๐ญ๐ข๐ฆ๐ ๐๐ก๐๐๐ค ๐๐จ๐ซ ๐ข๐ง๐ข๐ญ๐ข๐๐ฅ๐ข๐ณ๐๐ญ๐ข๐จ๐ง
Still, you only know this at runtime when the program fails, If you forget to initialize a late variable. Basically, you say โ Trust me to initialize d ever before it's read for the first time โ. So the compiler skips the initialization check and inserts a runtime check.
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๐- ๐๐ฎ๐ง๐ญ๐ข๐ฆ๐ ๐๐ก๐๐๐ค๐ฌ ๐๐ซ๐ ๐ฌ๐ค๐ข๐ฉ๐ฉ๐๐ ๐๐ญ ๐ก๐ข๐ ๐ก๐๐ซ ๐จ๐ฉ๐ญ๐ข๐ฆ๐ข๐ณ๐๐ญ๐ข๐จ๐ง ๐ฅ๐๐ฏ๐๐ฅ๐ฌ
There's a stir to allow skipping the initialization checks in some shapes. This may beget segfault which is harder to probe than an ordinary exception.
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๐- ๐๐๐ค๐๐ฌ ๐ฆ๐จ๐ซ๐ ๐ฆ๐๐ฆ๐จ๐ซ๐ฒ
Your program needs to know if a late variable has been initialized or not. For this, the compiler frequently creates a retired internal variable that takes memory.
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๐- ๐๐๐๐ข๐ญ๐ข๐จ๐ง๐๐ฅ ๐ซ๐๐๐ ๐๐ง๐ โ ๐ข๐ โ ๐๐๐๐จ๐ซ๐ ๐๐๐๐ก ๐ซ๐๐๐
Every time you read a late variable the program must insure it's initialized, so a redundant check is added.
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๐- ๐๐๐๐ข๐ญ๐ข๐จ๐ง๐๐ฅ ๐ฐ๐ซ๐ข๐ญ๐ ๐๐๐๐จ๐ซ๐ ๐๐๐๐ก ๐ฐ๐ซ๐ข๐ญ๐.
Every time you write to a late variable the program sets the internal flag to note that it's initialized.
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Hopefully, that helped. Did it? ๐
Follow for further ๐
This content originally appeared on DEV Community and was authored by Areeba Farooq
Areeba Farooq | Sciencx (2022-07-12T10:21:08+00:00) Why Avoid Late Variables in Dart ??. Retrieved from https://www.scien.cx/2022/07/12/why-avoid-late-variables-in-dart/
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