I was wondering, how are you supposed to use std.file : read in @safe code when it returns a void[] but you want to get all bytes in the file?

Is void[] really the correct type it should be returning instead of ubyte[] when it just reads a (binary) file to memory? Or should void[] actually be castable to ubyte[] in @safe code?

I would say it should return a ubyte[].

On Monday, 6 January 2020 at 10:07:37 UTC, WebFreak001 wrote:
> Or should void[] actually be castable to ubyte[] in @safe code?

Definitely not with the current semantics, since a void[] can alias pointers in @safe code.
See: https://issues.dlang.org/show_bug.cgi?id=20345

On Monday, 6 January 2020 at 10:07:37 UTC, WebFreak001 wrote:
> I was wondering, how are you supposed to use std.file : read in @safe code when it returns a void[] but you want to get all bytes in the file?
>
> Is void[] really the correct type it should be returning instead of ubyte[] when it just reads a (binary) file to memory? Or should void[] actually be castable to ubyte[] in @safe code?

I definitely think it should return ubyte[].
void[] is a very special abstraction that shouldn't be used at all if you don't know very well what you're doing.

On 1/6/20 5:07 AM, WebFreak001 wrote:
> I was wondering, how are you supposed to use std.file : read in @safe code when it returns a void[] but you want to get all bytes in the file?
> 
> Is void[] really the correct type it should be returning instead of ubyte[] when it just reads a (binary) file to memory? Or should void[] actually be castable to ubyte[] in @safe code?

I feel like this conversation has been had before. But I think it should be ubyte[]. Not sure why it's void[]. Perhaps for symmetry with write, which takes void[] (for good reason)?

-Steve

On 1/6/20 5:07 AM, WebFreak001 wrote:
> Or should void[] actually be castable to ubyte[] in @safe code?

No, because you can implicitly cast anything to void[], including pointer arrays.

Possibly const(ubyte[]).

-Steve

On Monday, January 6, 2020 8:52:01 AM MST Steven Schveighoffer via Digitalmars-d-learn wrote:
> On 1/6/20 5:07 AM, WebFreak001 wrote:
> > I was wondering, how are you supposed to use std.file : read in @safe code when it returns a void[] but you want to get all bytes in the file?
> >
> > Is void[] really the correct type it should be returning instead of ubyte[] when it just reads a (binary) file to memory? Or should void[] actually be castable to ubyte[] in @safe code?
>
> I feel like this conversation has been had before. But I think it should be ubyte[]. Not sure why it's void[]. Perhaps for symmetry with write, which takes void[] (for good reason)?

I think that in previous discussions, it was decided that in general, when you're dealing with something like reading from / write to a file or a socket, writing should accept void[], because then you can write any binary data to it without casting (including objects which are being serialized), whereas reading should give you ubyte[] or const(ubyte)[], because what you're getting from the OS is bytes of data, and it's up to the program to figure out what to do with them.

- Jonathan M Davis