Redirecting stdout

[Nathan Reed]

Robert Fraser wrote:
> Bill Baxter wrote:
>> Robert Fraser wrote:
>>> I'd like at a particular point in my program to temporarily ignore 
>>> all stdout (i.e. not have it written to the stream)... is there a way 
>>> to do this? I want my program to work under both Phobos & Tango, so a 
>>> way for both libraries would be great.
>>>
>>
>> Phobos just uses the underlying C stream objects in the end, so you 
>> can use freopen on those.  Note that std.cstream functions will throw 
>> exceptions if the standard output streams are not open, so the code 
>> below freopens them to point to /dev/null or Nul.
>>
>> Don't know if there's a better way, but this way has been working for me.
>>
>> version(Tango) {
>>     ??
>> }
>> else {
>>     static this() {
>>         // redefine dout,derr,dlog to prevent IO exceptions
>>         version(Windows) {
>>             std.c.stdio.freopen("Nul", "w", dout.file);
>>             std.c.stdio.freopen("Nul", "w", derr.file);
>>         }
>>         else {
>>             std.c.stdio.freopen("/dev/null", "w", dout.file);
>>             std.c.stdio.freopen("/dev/null", "w", derr.file);
>>         }
>>     }
>> }
> 
> Thanks; that's what I needed! But how do I capture the current 
> stdout/stderr so I can get them back (I've never done these scary stream 
> thing before, obviously).

I think you can just save the old values of dout.file and derr.file, and 
restore them later on (remembering to close the 'reopened' streams when 
you do so).

Thanks,
Nathan Reed