• Nick (24/24) Aug 12 2004 I've been having some problems with getting writef() to work properly. T...
• h3r3tic (5/18) Aug 12 2004 the same on winxp, it doesnt flush, thats the problem.
• Lars Ivar Igesund (7/33) Aug 12 2004 This is apparantly neither a D nor a writef problem, but a 'feature' of
• h3r3tic (7/12) Aug 13 2004 Mostly, yip... however there should be a nicer function than calling
• Dawid =?UTF-8?B?Q2nEmcW8YXJraWV3aWN6?= (5/10) Aug 13 2004 Something like "tie()" in C++ streams.
• Nick (8/15) Aug 13 2004 The simplest solution would be to add a flushWhatever() call to the end ...
• Nick (14/14) Aug 13 2004 Another problem is that std.stream.stdout and writef(ln) use different p...

Nick <Nick_member pathlink.com> writes:

I've been having some problems with getting writef() to work properly. The
following example illustrates the problem:

writef("Computing:");
// Some time consuming calculation
for(int i; i<5000; i++)
for(int j; j<10000; j++)
floor(1.23);
writefln(" done.");

This seems to do the entire calculation before writing anything to screen. In
other words, writef doesn't actually write anything to screen until writefln is
called. (I'm on linux, btw.)

This is especially a problem with prompts:

// Btw this line should have been unnecessary :)
alias std.stream.stdin stdin;

writefln("On the next line you are asked to type your name");
writef("Type your name here: ");
char[] name = stdin.readLine();
writefln("Hello ", name, ", that is a nice name!");

The output I get is:

On the next line you are asked to type your name
Nick
Type your name here: Hello Nick, that is a nice name!

I have no idea what the cause of this problem is.

Nick

h3r3tic <h3r3tic dev.null> writes:

Nick wrote:
 I've been having some problems with getting writef() to work properly. The
 following example illustrates the problem:
 
 writef("Computing:");
 // Some time consuming calculation
 for(int i; i<5000; i++)
 for(int j; j<10000; j++)
 floor(1.23);
 writefln(" done.");
 
 This seems to do the entire calculation before writing anything to screen. In
 other words, writef doesn't actually write anything to screen until writefln is
 called. (I'm on linux, btw.)

the same on winxp, it doesnt flush, thats the problem.
atm the best solution i can come up with is probably calling

fflush(std.stdio.stdout);

just after writef("Computing:");

Lars Ivar Igesund <larsivar igesund.net> writes:

This is apparantly neither a D nor a writef problem, but a 'feature' of 
some (most?) consoles. It's the consoles that don't flush until they 
stumble upon a newline. Either add \n to the output of your writef or 
change it to a writefln. I remember this happening when using printf in 
C a long time ago.

Lars Ivar Igesund

h3r3tic wrote:

 Nick wrote:
 
 I've been having some problems with getting writef() to work properly. 
 The
 following example illustrates the problem:

 writef("Computing:");
 // Some time consuming calculation
 for(int i; i<5000; i++)
 for(int j; j<10000; j++)
 floor(1.23);
 writefln(" done.");

 This seems to do the entire calculation before writing anything to 
 screen. In
 other words, writef doesn't actually write anything to screen until 
 writefln is
 called. (I'm on linux, btw.)

 
 
 the same on winxp, it doesnt flush, thats the problem.
 atm the best solution i can come up with is probably calling
 
 fflush(std.stdio.stdout);
 
 just after writef("Computing:");

h3r3tic <h3r3tic dev.null> writes:

Lars Ivar Igesund wrote:
 This is apparantly neither a D nor a writef problem, but a 'feature' of 
 some (most?) consoles. It's the consoles that don't flush until they 
 stumble upon a newline. Either add \n to the output of your writef or 
 change it to a writefln. I remember this happening when using printf in 
 C a long time ago.

Mostly, yip... however there should be a nicer function than calling 
file flush on a C output buffer :] and input should be synchronized with 
output so that when one wants to read from the keybrd, everything is 
flushed to the console... maybe also adding a special flush object to 
the stream could be nice... like writef("foobar", flush); and the 
toStream of instance flush would flush the buffers :>

Dawid =?UTF-8?B?Q2nEmcW8YXJraWV3aWN6?= <arael fov.pl> writes:

h3r3tic wrote:
 ...
 file flush on a C output buffer :] and input should be synchronized with
 output so that when one wants to read from the keybrd, everything is
 flushed to the console... maybe also adding a special flush object to
 ...

Something like "tie()" in C++ streams.
-- 
Dawid Ciężarkiewicz | arael
jid: arael fov.pl

Nick <Nick_member pathlink.com> writes:

In article <cfimuh$oak$1 digitaldaemon.com>, Dawid
=?UTF-8?B?Q2nEmcW8YXJraWV3aWN6?= says...
h3r3tic wrote:
 ...
 file flush on a C output buffer :] and input should be synchronized with
 output so that when one wants to read from the keybrd, everything is
 flushed to the console... maybe also adding a special flush object to
 ...

Something like "tie()" in C++ streams.

The simplest solution would be to add a flushWhatever() call to the end of
writef's definition, would it not? Buffering screen output can't be much of a
time saver anyway.

(Well unless you are writing megabytes of output and redirecting to file/pipe,
and I guess that is done sometimes. Hmm.)

Nick

Nick <Nick_member pathlink.com> writes:

Another problem is that std.stream.stdout and writef(ln) use different paths for
outputing to the same device, which is can cause problems.

std.stream.stdout actually does the job correctly (flushes even without the
newline), but independently of writef.

writef("snap ");
std.stream.stdout.writeString("crackle ");
writef("pop ");

Output is: "crackle snap pop ". Inserting a printf() into the mess is left as an
exercise for the reader ;-) Perhaps it would be possible to rewrite writef/ln to
just use std.stream.stdout? I.e.

// Pseudo-code
writef(...) { stdout.writeString(format(...)); }
writefln(...) { stdout.writeLine(format(...)); }

Nick