Parameter Data

Parameter data typically comes from any of three general sources: command line, CFG file, or DOS environment variables. The first two are straightforward. DOS environment variables are easily acquired by capturing the output of the DOS set command with the following line of Perl code:

$dos_env_vars_str = `set`;
Note: The special characters preceding and following the word "set" are not single quote characters; they are "backtick" characters.

The parameter values that drive a BRP run are made available to a user exit via DOS environment variables. BRP generates a DOS batch file that contains commands to set DOS environment variables. The user exit command is added to the end of the generated batch file and the batch file is executed using the backtick operator in Perl. The backtick operator executes a DOS command (in BRP the path to a batch file) in a shell "nested" inside of the shell of the BRP executable. The environment variables set up for a user exit only exist during the execution of that user exit. The environment variable commands are re-generated and run for each user exit.

In general, the format of parameter names and values should be standardized. BRP job parameters are of the form:
Parameter Name = Parameter Value

DOS environment variables and CFG file parameters are formatted in the same way. Command line parameters should follow the same standard. In general, command line parameters need to override the same named parameter from a CFG file or DOS environment. This allows a way to alter behavior in cases where the user may not have direct control over all the values.