STANDARD INPUT

STANDARD INPUT (SET)

Set Subcommand

Specify the name of a file that will be equivalenced to standard input.

By default, Dataplot reads commands from standard input (in Fortran, this is typically unit 5). The SET STANDARD INPUT is used to specify the name of a file to read from when input is expected from standard input.

In it's simplest usage, this is essentially equivalent to using a CALL command (this is demonstrated in the Program 1 and Program 2 sections below).

However, the SET STANDARD INPUT is typically used in a different context than the CALL command. Specifcally, it is motivated by the idea of having an external program control the input to Dataplot in a dynamic fashion.

For example, suppose you have a Python script and you would like that script to use Dataplot to perform a certain analysis. Suppose further that the user of the Python script has interactive control over what analysis he would like Dataplot to perform and when he would like that analysis performed. A typical sequence would then be

1. The Python script initiates Dataplot and has Dataplot execute the commands
   SET MAXIMUM COUNTER STANDARD INPUT 0
   SET DELAY STANDARD INPUT 2
   SET STANDARD INPUT POLL file.dp
   

   When the POLL CLOSE option is used, Dataplot does the following

   • Check for the existence of the file. If the file exists, then execute the commands in "file.dp" (the file name does not have to be "file.dp").

   • If the file does not exist, wait for a specified time and then check for the existence of the file again. Repeat until the file is found.

     The wait time is specified by the SET DELAY STANDARD INPUT command. The value is specified in seconds. If this command is not given, the default value is 2. The SET MAXIMUM COUNTER STANDARD INPUT command can be used to specify a maximum number of iterations. If this command is omitted or a value of 0 is given, then Dataplot will keep repeating until the file is found.

   If the POLL option is omitted, then Dataplot will check for the existence of the file only once. If the file is not found, nothing is done and standard input is restored to unit 5.

2. The last line of the "file.dp" file will typically contain one of the following lines
   SET STANDARD INPUT
   SET STANDARD INPUT CLOSE
   SET STANDARD INPUT CLOSE POLL
   
   where
   • The SET STANDARD INPUT command closes "file.dp" and reverts standard input back to the terminal. The "file.dp" file is not deleted.

   • The SET STANDARD INPUT CLOSE command close and deletes the "file.dp" file. Standard input reverts back to the terminal.

     This option is useful when the external program will not subsequently send additional commands to Dataplot.

   • The SET STANDARD INPUT CLOSE POLL command close and deletes the "file.dp" file. However, it resumes polling mode. That is, it effectively enters the command
     SET STANDARD INPUT POLL file.dp

     This option is used when the external program expects to subsequently send additonal commands to Dataplot.

The external program is not limited to Python. A similar sequence can be used within Perl, Tcl/TK, or any number of other programs.

SET STANDARD INPUT <fname> where <fname> is a file name.

This syntax equates standard input to <fname> It will only search for the existence of one time.

SET STANDARD INPUT

This syntax closes the file equated to standard input and reverts standard input back to the terminal.

SET STANDARD INPUT POLL <fname> where <fname> is a file name.

This syntax equates standard input to <fname>. It will continually search for the existence of <fname> (based on the SET MAXIMUM COUNTER STANDARD INPUT and SET DELAY STANDARD INPUT commands).

SET STANDARD INPUT CLOSE <fname> where <fname> is a file name.

This syntax closes and deletes the <fname> file and reverts standard input back to the terminal.

SET STANDARD INPUT POLL CLOSE <fname> where <fname> is a file name.

This syntax closes and deletes the <fname> file and reverts POLL mode for <fname>.

SET STANDARD INPUT commands.dp
SET STANDARD INPUT POLL commands.dp

SET RESUME POLL is a synonym for SET STANDARD INPUT POLL. However, no file name is entered. The previously defined file name (from the most recent SET STANDARD INPUT POLL command) will be used.

None

SET SUSPEND POLL is a synonym for SET STANDARD INPUT.
SET POLL SUSPEND is a synonym for SET STANDARD INPUT.
SET POLL RESUME is a synonym for SET RESUME POLL.

CALL

=

Execute the commands from an external file.

Program Control

2016/01

 
.  Put these lines in the external file
.
.     stdin.dp
.
.  These commands will be executed by the Program 2 example.
.
print "in file stdin.dp"
let a = 3
let b = 4
set standard input
    

 
. Execute the commands in file stdin.dp
.
set standard input stdin.dp