Consider adding runtime-defined endianness about byteorder HOT 8 CLOSED

@netvl Hmm, is there any particular reason why NativeEndian doesn't work for you? (This otherwise looks like a dupe of #18.)

from byteorder.

@netvl Oh, I misread your question. I guess I'm not following. What code have you tried? You should be able to invoke either endianness by calling e.g., BigEndian::read_u32 or LittleEndian::read_u32.

from byteorder.

I'd like to pass the actual endianness to read functions at runtime, something like

let byte_order = if <some check> { LittleEndian } else { BigEndian };
let n = source.read_u16(byte_order);

Here the required byte order is determined at runtime. I also can't use ByteOrder as a trait object because all its methods are static (and anyway, they don't work with Read directly).

from byteorder.

@netvl Define some helper functions? e.g.,

enum Endian { Little, Big }

fn read_u16(source: &[u8], endian: Endian) -> byteorder::Result<u16> {
    match endian {
        Endian::Little => byteorder::LittleEndian::read_u16(source),
        Endian::Big => byteorder::BigEndian::read_u16(source),
    }
}

read_u16(&[...], Endian::Little)

from byteorder.

Well, yes, that's what I've done. I've written an extension trait for Read and a macro which generates all the necessary methods. I just think that this should be provided by the library :)

from byteorder.

@netvl I see. I'm not totally convinced the added API surface is really worth it ("I'm trying to use byteorder but there are three different ways to read a big endian number, which one should I use?"). I can see how they would be useful occasionally though.

from byteorder.

Maybe this problem is solved by the proper documentation. Something along the following lines:

There are three ways to read a number in a specific endianness:

• by using methods of ByteOrder trait, like BigEndian::read_u16(buf), if you need to read a number from a byte slice with a statically known byte order;
• by using methods of ReadBytesExt extension trait, like source.read_u16::<BigEndian>(), if you need to read a number from a Read instance with a statically known byte order;
• or by using methods of ReadBytesDynamicExt extension trait, like source.read_u16(byte_order), if you need to read a number from a Read instance when the byte order is determined at runtime.

from byteorder.

I still personally feel like expecting one to write a helper function for this is perfectly fine. I'd really rather not make the API more complex than it already is.

from byteorder.