CODEWITHSUNDEEP
postscript
juFo
juFo

Reputation: 18577

PostScript control loop - server loop

I'm investigating the start/server loop. The Insi de Postscript book explains the /start procedure. One part of that procedure is the control loop:

...
{
  //serverdict /server get exec

  //serverdict begin

  setstreams
  setnulldevice
  /execjob
  load

  end
  exec
} loop
...

Now i'm trying to find out what /server exactly does and how it might look like (in its most simple form).

//serverdict /server get exec

This line above gets the server procedure and executes it immediately.

Now I have a server loop like this:

/server {
 { % server loop
    (i'm in a server loop) print flush
    (%stdin) run
 }
 loop
} def

but i'm stuck in an infinite loop. How and when can the server loop ever go to the next step (//serverdict begin setstreams etc...) as it is currently in an infinite loop?

Upvotes: 1

Views: 271

Answers (1)

Jim DeLaHunt
Jim DeLaHunt

Reputation: 11405

In the control loop you show, the object bound to the name server does not seem to loop the way your code does. It seems to do some initialisation and then return. The expression /execjob load seems to run the current job. Outside of all that is a { ... } loop expression which seems to be the server loop which you implemented.

If you want to insert your own server code into the supplied loop, you need to work with the contents of //serverdict which your interpreter supplies. If you want to write your own server loop, it seems like you need to go out one level, and replace that entire { ... } loop expression, and maybe //serverdict as well.

If you want to "find out what /server exactly does and how it might look like…", how about looking at it? The moral equivalent of:

//serverdict /server get == flush

Upvotes: 1

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