bug: Console buffer not flushed at right time

[Jonathan M Davis]

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- Jonathan M Davis

On Tuesday, February 07, 2012 15:49:19 Kevin Brogan wrote:
> ==========================================================
> Bug:
> ----------------------------------------------------------
> 
> 1) Console output buffer is not flushed when it should be.
> 
> ==========================================================
> Example Code:
> ----------------------------------------------------------
> 
> import std.stdio;
> 
> extern (Windows): uint GetConsoleOutputCP();
> extern (Windows): bool SetConsoleOutputCP(uint codePageId);
> 
> void main()
> {
> auto oldCP = [GetConsoleOutputCP(),SetConsoleOutputCP(65001)];
> scope(exit) if(oldCP[1]) SetConsoleOutputCP(oldCP[0]);
> 
> string str = "H\u266a!";
> 
> foreach (wchar c; str)
> {
> write(c,' ');
> }
> }
> 
> 
> ==========================================================
> What should happen:
> ----------------------------------------------------------
> 
> When main starts, the console codepage is set to UTF 8. Characters are then
> output to the console, and then the console codepage is reset to what it
> was prior to program execution. The reset is neccessary to preserve the
> console environment that exists prior to the program being run.
> 
> ==========================================================
> What happens instead:
> ----------------------------------------------------------
> 
> Instead of outputting the characters while the console is in the requested
> codepage, output is buffered. When main exits, the buffer is flushed, but
> after the scope(exit) statement has reset the codepage, so the flushed
> output is output while the wrong codepage is selected.
> 
> ==========================================================
> Work arounds:
> ----------------------------------------------------------
> 
> a) Get console input first - Buffer appears to be flushed before accepting
> input from the console.
> 
> b) Output a carriage return - Buffer appears to be flushed after every
> carriage return
> 
> c) Explicit flush in scope(exit) - import std.cstream, call dout.flush() in
> the scope(exit) statement
> 
> d) Patch the runtime to set the console codepage to unicode after opening a
> console and then set it back to what it was on program exit - Makes sense
> since all strings are output in unicode, and I wouldn't have to use win32
> apis to get logical behavior.
> 
> 
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