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digitalmars.D.learn - Delay function?

reply Brendan <brenzie gmail.com> writes:
I looked through the Phobos page, but haven't found anything like it. Is there
a sort of delay function anywhere in Phobos?
Sep 02 2008
parent reply Brendan <brenzie gmail.com> writes:
Brendan Wrote:


 I looked through the Phobos page, but haven't found anything like it. Is there
a sort of delay function anywhere in Phobos?



Well, I just used 'sleep' from the Linux shell instead. I don't understand yet
what I'm doing wrong with the following function, though. Could someone explain
and advise?


void scrollString( char[] s ) {
    for ( int i = 0; i < s.length; i++ )
      writef( s[i] );
      system( "sleep 0.2" );
  }
Sep 02 2008
next sibling parent reply "Jarrett Billingsley" <jarrett.billingsley gmail.com> writes:
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Content-Transfer-Encoding: 7bit
Content-Disposition: inline

On Tue, Sep 2, 2008 at 7:11 AM, Brendan <brenzie gmail.com> wrote:


 Brendan Wrote:


 I looked through the Phobos page, but haven't found anything like it. Is




 Well, I just used 'sleep' from the Linux shell instead. I don't understand
 yet what I'm doing wrong with the following function, though. Could someone
 explain and advise?


 void scrollString( char[] s ) {
    for ( int i = 0; i < s.length; i++ )
      writef( s[i] );
      system( "sleep 0.2" );
  }



around the body of the for loop, this isn't Python ;)
Sep 02 2008
parent reply Brendan <brenzie gmail.com> writes:
Jarrett Billingsley Wrote:



 </blockquote></div><br>If you're expecting it to pause after each character..
you're missing braces around the body of the for loop, this isn't Python
;)<br></div>
 



Oooooh, what a foolish mistake! How could I forget that? Thanks for pointing it
out.

But the result isn't fruitful, though. When I run it, all I get is an empty
screen, then after many seconds the whole string is displayed at once (not to
mention I set the sleep time to 0.1 seconds). I'm probably missing something.
Any idea?
Sep 02 2008
next sibling parent reply "Chris R. Miller" <lordSaurontheGreat gmail.com> writes:
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Content-Transfer-Encoding: quoted-printable

Brendan wrote:

 Jarrett Billingsley Wrote:
=20
=20

 </blockquote></div><br>If you're expecting it to pause after each char=






 Python ;)<br></div>



 Oooooh, what a foolish mistake! How could I forget that? Thanks for poi=




=20
 But the result isn't fruitful, though. When I run it, all I get is an e=



e (not to mention I set the sleep time to 0.1 seconds). I'm probably miss=
ing something. Any idea?

Flush the output?



 Sep 02 2008



  parent reply Brendan <brenzie gmail.com>  writes:


Jarrett Billingsley Wrote:


 On Tue, Sep 2, 2008 at 1:37 PM, Chris R. Miller <
 lordSaurontheGreat gmail.com> wrote:
 

 Brendan wrote:

 Jarrett Billingsley Wrote:



 </blockquote></div><br>If you're expecting it to pause after each






 isn't Python ;)<br></div>



 Oooooh, what a foolish mistake! How could I forget that? Thanks for




 But the result isn't fruitful, though. When I run it, all I get is an



 (not to mention I set the sleep time to 0.1 seconds). I'm probably missing
 something. Any idea?

 Flush the output?



 
 foreach(ch; s) { write(ch); fflush(stdout); system("pause 0.2"); }



Thanks! With a little quick tweaking it worked. But, even though I see the
effective result, I don't entirely understand what it means "to flush" the
output. I've never heard of this concept before and Google doesn't seem to
return any useful answers. Could you explain?



 Sep 02 2008



 next sibling parent reply BCS <ao pathlink.com>  writes:


Reply to Brendan,


 Jarrett Billingsley Wrote:
 

 On Tue, Sep 2, 2008 at 1:37 PM, Chris R. Miller <
 lordSaurontheGreat gmail.com> wrote:

 Brendan wrote:
 

 Jarrett Billingsley Wrote:
 

 </blockquote></div><br>If you're expecting it to pause after each
 






 this isn't Python ;)<br></div>
 

 Oooooh, what a foolish mistake! How could I forget that? Thanks for
 



 

 But the result isn't fruitful, though. When I run it, all I get is
 an
 



 at once (not to mention I set the sleep time to 0.1 seconds). I'm
 probably missing something. Any idea?
 
 Flush the output?
 



 
 foreach(ch; s) { write(ch); fflush(stdout); system("pause 0.2"); }
 



 the effective result, I don't entirely understand what it means "to
 flush" the output. I've never heard of this concept before and Google
 doesn't seem to return any useful answers. Could you explain?
 



The act of making the screen show text is rather costly in time, so generally 
libs buffer your output, often until a newline or some preset amount. Flush 
just forces a buffer flush and the resultant output.



 Sep 02 2008



  parent reply Brendan <brenzie gmail.com>  writes:


BCS Wrote:


 Reply to Brendan,
 

 Jarrett Billingsley Wrote:
 

 On Tue, Sep 2, 2008 at 1:37 PM, Chris R. Miller <
 lordSaurontheGreat gmail.com> wrote:

 Brendan wrote:
 

 Jarrett Billingsley Wrote:
 

 </blockquote></div><br>If you're expecting it to pause after each
 






 this isn't Python ;)<br></div>
 

 Oooooh, what a foolish mistake! How could I forget that? Thanks for
 



 

 But the result isn't fruitful, though. When I run it, all I get is
 an
 



 at once (not to mention I set the sleep time to 0.1 seconds). I'm
 probably missing something. Any idea?
 
 Flush the output?
 



 
 foreach(ch; s) { write(ch); fflush(stdout); system("pause 0.2"); }
 



 the effective result, I don't entirely understand what it means "to
 flush" the output. I've never heard of this concept before and Google
 doesn't seem to return any useful answers. Could you explain?
 



 The act of making the screen show text is rather costly in time, so generally 
 libs buffer your output, often until a newline or some preset amount. Flush 
 just forces a buffer flush and the resultant output.
 
 



Thanks for your responses, BCS. This is the first time I'm kind of
communicating through a newsgroup such as this, as I'm normally used to a
forum. Why are your two messages separate from the thread?



 Sep 02 2008



  parent reply BCS <ao pathlink.com>  writes:


Reply to Brendan,


 Thanks for your responses, BCS. This is the first time I'm kind of
 communicating through a newsgroup such as this, as I'm normally used
 to a forum. Why are your two messages separate from the thread?
 



If you are using the D web site interface, because it's broken (and has been 
for years). Best approach is to get a "real" newsgroup client program,
thunderbird 
works, I use Omea by jetbrains and IIRC Outlook also does newsgroups.



 Sep 02 2008



  parent  Brendan <brenzie gmail.com>  writes:


BCS wrote:

 Reply to Brendan,
 

 Thanks for your responses, BCS. This is the first time I'm kind of
 communicating through a newsgroup such as this, as I'm normally used
 to a forum. Why are your two messages separate from the thread?



 If you are using the D web site interface, because it's broken (and has 
 been for years). Best approach is to get a "real" newsgroup client 
 program, thunderbird works, I use Omea by jetbrains and IIRC Outlook 
 also does newsgroups.
 
 






 Sep 03 2008



prev sibling  parent  Brendan <brenzie gmail.com>  writes:


Denis Koroskin Wrote:


 Google for "buffering". When you print something, it doesn't get displayed  
 immediately. Instead, the string is copied to some internal buffer and  
 when it gets full (or close to full) it is then flushed, i.e. its contents  
 copied to the console and buffer size reset. Something like this:
 
 char[] buffer;
 
 void writefln(char[] str)
 {
    buffer ~= str;
    if (buffer.length > 1024) {
      doTheRealPrinting(buffer);
      buffer.length = 0;
    }
 }



Ahhh, a buffer!

So basically, in the correct piece of code (the scroll function) a few messages
back, in the for loop, the buffer is constantly unloading the characters from
itself? It is so beautiful. Thanks :)



 Sep 02 2008



prev sibling  parent reply bearophile <bearophileHUGS lycos.com>  writes:


Brendan:

 Oooooh, what a foolish mistake! How could I forget that? Thanks for pointing
it out.



It's a mistake, but in the past years I have seen several similar mistakes in
real programs written in C-like languages. That's why I'm a fan of semantically
significant indentations :-) (Or of a built-in lint-like capability of the
language that signals such indentation errors are syntax errors).

Bye,
bearophile



 Sep 02 2008



  parent  "Steven Schveighoffer" <schveiguy yahoo.com>  writes:


"bearophile" wrote

 Brendan:

 Oooooh, what a foolish mistake! How could I forget that? Thanks for 
 pointing it out.



 It's a mistake, but in the past years I have seen several similar mistakes 
 in real programs written in C-like languages. That's why I'm a fan of 
 semantically significant indentations :-) (Or of a built-in lint-like 
 capability of the language that signals such indentation errors are syntax 
 errors).



Any reasonable syntax highlighting editor should show you that you forgot 
something.

In vim, if I forget something like this, the second statement's indent jumps 
back to the same level as the if statement, signalling that I forgot to add 
the curly brace.

-Steve 



 Sep 02 2008



prev sibling next sibling parent  BCS <ao pathlink.com>  writes:


Reply to Brendan,


 Brendan Wrote:
 

 I looked through the Phobos page, but haven't found anything like it.
 Is there a sort of delay function anywhere in Phobos?
 



 understand yet what I'm doing wrong with the following function,
 though. Could someone explain and advise?
 
 void scrollString( char[] s ) {
 for ( int i = 0; i < s.length; i++ )
 writef( s[i] );
 system( "sleep 0.2" );
 }



IIRC the are the standard sleep and usleep functions in std.c.something



 Sep 02 2008



prev sibling next sibling parent  "Jarrett Billingsley" <jarrett.billingsley gmail.com>  writes:


Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

On Tue, Sep 2, 2008 at 1:37 PM, Chris R. Miller <
lordSaurontheGreat gmail.com> wrote:


 Brendan wrote:

 Jarrett Billingsley Wrote:



 </blockquote></div><br>If you're expecting it to pause after each






 isn't Python ;)<br></div>



 Oooooh, what a foolish mistake! How could I forget that? Thanks for




 But the result isn't fruitful, though. When I run it, all I get is an



 (not to mention I set the sleep time to 0.1 seconds). I'm probably missing
 something. Any idea?

 Flush the output?




foreach(ch; s) { write(ch); fflush(stdout); system("pause 0.2"); }



 Sep 02 2008



prev sibling  parent  "Denis Koroskin" <2korden gmail.com>  writes:


On Wed, 03 Sep 2008 00:24:02 +0400, Brendan <brenzie gmail.com> wrote:


 Jarrett Billingsley Wrote:


 On Tue, Sep 2, 2008 at 1:37 PM, Chris R. Miller <
 lordSaurontheGreat gmail.com> wrote:


 Brendan wrote:

 Jarrett Billingsley Wrote:



 </blockquote></div><br>If you're expecting it to pause after each










 isn't Python ;)<br></div>



 Oooooh, what a foolish mistake! How could I forget that? Thanks for




 But the result isn't fruitful, though. When I run it, all I get is  







 empty screen, then after many seconds the whole string is displayed  




 (not to mention I set the sleep time to 0.1 seconds). I'm probably  




 something. Any idea?

 Flush the output?




 foreach(ch; s) { write(ch); fflush(stdout); system("pause 0.2"); }



 Thanks! With a little quick tweaking it worked. But, even though I see  
 the effective result, I don't entirely understand what it means "to  
 flush" the output. I've never heard of this concept before and Google  
 doesn't seem to return any useful answers. Could you explain?



Google for "buffering". When you print something, it doesn't get displayed  
immediately. Instead, the string is copied to some internal buffer and  
when it gets full (or close to full) it is then flushed, i.e. its contents  
copied to the console and buffer size reset. Something like this:

char[] buffer;

void writefln(char[] str)
{
   buffer ~= str;
   if (buffer.length > 1024) {
     doTheRealPrinting(buffer);
     buffer.length = 0;
   }
}



 Sep 02 2008