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digitalmars.D.bugs - [Issue 2545] New: write(f)(ln) throws StdioException("Bad file descriptor") when no console is available

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2545

           Summary: write(f)(ln) throws StdioException("Bad file
                    descriptor") when no console is available
           Product: D
           Version: 2.022
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: 2korden gmail.com


It throws an exception at first call to flush when no stdout is a available
(e.g. code compiled for SUBSYSTEM WINDOWS) and it causes some problems for GUI
apps. I believe it should fail immediately (at the very first call to write) or
(preferably) never fail at all. Otherwise, it leads to problem that are hard to
track (e.g. all the unittests pass, but an application fails silently with no
reason after a few hours of execution). I think its behavior should be close to
printf which suppresses an error and goes on.

Test code:

import std.stdio;

void main()
{
    while(true) {
        //printf("!"); // works forever
        write("!");    // fails at first call to flush
    }
}


--
Dec 29 2008
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2545


smjg iname.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |smjg iname.com
            Summary|write(f)(ln) throws         |write(f)(ln) delays throwing
                   |StdioException("Bad file    |StdioException("Bad file
                   |descriptor") when no console|descriptor") when no console
                   |is available                |is available





How can it never fail at all?  Or are you confusing "fail" with "throw an
exception"?

In any case, failing silently is completely the wrong approach.  If there is no
stdout to write to, it should throw an immediate exception.  That's what
exceptions are there for.

printf doesn't suppress errors.  It returns a value that indicates success or
failure.  This is because C doesn't have exception handling, and so C functions
have to improvise.  In D, OTOH, the only right thing to do is use exceptions to
indicate failure.
http://www.digitalmars.com/d/1.0/errors.html


--
Dec 29 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2545






Currently write forwards calls to the corresponding system routines and
faithfully transforms their error codes into exceptions. I agree with Steward
that non-failure is not an option :o), but I also agree that this state of
affairs may also cause problems. 

I could put a check in write to make it fail sooner, but I'm thinking that
maybe that behavior on Windows is intentional, e.g. to allow users to create
their own console and flush to them or whatnot.


--
Dec 29 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2545








 Currently write forwards calls to the corresponding system routines and
 faithfully transforms their error codes into exceptions. I agree with Steward


I meant Stewart, sorry. -- Andrei


--
Dec 29 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2545








 I could put a check in write to make it fail sooner, but I'm thinking that
 maybe that behavior on Windows is intentional, e.g. to allow users to create
 their own console and flush to them or whatnot.


What do you mean by this?


--
Dec 29 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2545


Andrei Alexandrescu <andrei metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |andrei metalanguage.com
         AssignedTo|nobody puremagic.com        |andrei metalanguage.com


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Oct 11 2009
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2545


Andrei Alexandrescu <andrei metalanguage.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |WONTFIX



12:07:13 PDT ---
I think the behavior is as designed now. If not, please reopen.

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Sep 26 2010