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Example

Suppose the parameters of DISP are specified as follows:
INTERFACE DISP
   .
   PARAMETER IMAGE
         .
      VPATH GLOBAL
      ASSOCIATION <->GLOBAL.IMAGE
         .
   ENDPARAMETER
   PARAMETER DISPLAY
         .
      VPATH 'CURRENT,DEFAULT'
      DEFAULT XWINDOWS
         .
   ENDPARAMETER
   PARAMETER LIMITS
         .
      VPATH DYNAMIC
         .
   ENDPARAMETER
      .
ENDINTERFACE
Then, if the user just types:
disp
(i.e. does not give any parameter values), the following actions occur:

When the program asks for the value of the IMAGE parameter, no value has been given so the first part of the VPATH specification is extracted (GLOBAL). This path specifier tells the system to look for a value of the associated parameter (GLOBAL.IMAGE). If it has a value, this value is taken as the value of IMAGE; if not, the resolution path is exhausted so the user will be prompted for a value for IMAGE.

When the program asks for a value of DISPLAY, the specifier CURRENT is extracted from the VPATH. If DISPLAY has a current value, the same value is used again; if not, the static default value (XWINDOWS) specified in the Interface File is taken.

Similarly, when the program asks for the value of LIMITS, the system attempts to use the dynamic default suggested by the program. If no dynamic default has been set, the user is prompted for a value for LIMITS.



next up previous 63
Next: Run-time Modification of VPATH Action
Up: The VPATH Field
Previous: The VPATH Field

ADAM Interface Module Reference Manual
Starlink User Note 115
A J Chipperfield, B D Kelly, S L Wright
3 September 2002
E-mail:ussc@star.rl.ac.uk

Copyright © 2002 Council for the Central Laboratory of the Research Councils