From: "nobu (Nobuyoshi Nakada) via ruby-core" Date: 2025-12-19T03:56:41+00:00 Subject: [ruby-core:124312] [Ruby Feature#21796] unpack variant that returns the final offset Issue #21796 has been reported by nobu (Nobuyoshi Nakada). ---------------------------------------- Feature #21796: unpack variant that returns the final offset https://bugs.ruby-lang.org/issues/21796 * Author: nobu (Nobuyoshi Nakada) * Status: Open ---------------------------------------- mame (Yusuke Endoh) wrote in #note-4: > It's a shame `unpack` doesn't tell you how many bytes it read. You'd probably want a `unpack` variant that returns the final offset too, or a specifier that returns the current offset (like `o`?). > > ```ruby > bytes = "\x01\x02\x03" > offset = 0 > leb128_value1, offset = bytes.unpack("Ro", offset: offset) #=> 1 > leb128_value2, offset = bytes.unpack("Ro", offset: offset) #=> 2 > leb128_value3, offset = bytes.unpack("Ro", offset: offset) #=> 3 > ``` mame (Yusuke Endoh) wrote in #note-6: > > You could tell how many bytes you read based on the size of the leb128_value returned. > > That apparoach is unreliable because LEB128 is redundant. For example, both `"\x03"` and `"\x83\x00"` are valid LEB128 encodings of the value 3. > See the note of the section Values - Integers, in the Wasm spec. > https://webassembly.github.io/spec/core/binary/values.html#integers -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/