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digitalmars.D.learn - safe std.file.read

reply WebFreak001 <d.forum webfreak.org> writes:
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?
Jan 06 2020
next sibling parent Dennis <dkorpel gmail.com> writes:
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
Jan 06 2020
prev sibling next sibling parent Dominikus Dittes Scherkl <dominikus.scherkl continental-corporation.com> writes:
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.
Jan 06 2020
prev sibling next sibling parent reply Steven Schveighoffer <schveiguy gmail.com> writes:
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
Jan 06 2020
parent Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:
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
Jan 06 2020
prev sibling parent Steven Schveighoffer <schveiguy gmail.com> writes:
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
Jan 06 2020