Replace MappedWrite's magic u8 constant with byte string literal
#780
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The `NEWLINE_ASCII_BYTE` constant only really existed because it's otherwise not obvious that the `0x0Au8` u8 value represents an ASCII newline byte. However, we can replace the `0x0Au8` u8 with a byte string literal of `b'\n'` which is identical in it's value, but much easier to reason about. The byte string literal form is what the Rust stdlib uses in several places: https://github.com/rust-lang/rust/blob/1.76.0/library/core/src/num/mod.rs#L1023 https://github.com/rust-lang/rust/blob/1.76.0/library/core/src/escape.rs#L20 https://github.com/rust-lang/rust/blob/1.76.0/library/std/src/io/buffered/linewritershim.rs#L47
Malax
approved these changes
Feb 14, 2024
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The
NEWLINE_ASCII_BYTEconstant only really existed because it's otherwise not obvious that the0x0Au8u8 value represents an ASCII newline byte.However, we can replace the
0x0Au8u8 with a byte string literal ofb'\n'which is identical in it's value, but much easier to reason about.The byte string literal form is what the Rust stdlib uses in several places:
https://github.com/rust-lang/rust/blob/1.76.0/library/core/src/num/mod.rs#L1023
https://github.com/rust-lang/rust/blob/1.76.0/library/core/src/escape.rs#L20
https://github.com/rust-lang/rust/blob/1.76.0/library/std/src/io/buffered/linewritershim.rs#L46
(I spotted this whilst reviewing #721's usage of
MappedWrite- since I thinkBuildpackOutput::start_streammight also need to start handling newline bytes in the closure passed toline_mapped, and was otherwise thinking we'd need to expose theNEWLINE_ASCII_BYTEconstant tobuild_output, until I realised we didn't really need the magic0x0Au8value after all.)