<?fishup>
Description
When a <?fishup> processing instruction is used, the values of all existing FISH variables is preserved. This will take into account all set/reset actions that follow the command and change the value of the variable(s). When PTC ALD encounters a subsequent <?fishdown> command the FISH variables are reset to the values they held when the last up was made. These commands enable PTC ALD to capture a set of variables and their values and use them for the purposes of inheritance.
<?fishup [hashno]> <?fishdown [hashno]>
Example 460. Preserve variable values using <?fishup> and <?fishdown>
<?show"^[fish0,test]"hello>
<?show$^[fish0, test]
These two lines will firstly set the value of a FISH variable called test in hash 0 to "hello", then return the value of the FISH variable test from hash 0. Here the output will be "hello".
<?fishup0>
<?show"^[fish0,test]"world>
<?show$^[fish0, test]
Whereas these three lines, with the inclusion of the <?fishup> command, will reset the value of the same variable in hash 0 to "world".
<?fishdown 0>
<?show$^[fish0, test]>
Following the <?fishup> command with these two lines will reset the value of the same variable to the value it held before the <?fishup> command was processed. The output here will now be "hello".
Syntax
<?fishup hash_num:n>
<?fishup>
|
[no parameter]
|
Preserve values of FISH variables.
|
|
hash_num
|
The hash number to which the operation should write the new value of the FISH variables. As with setting or retrieving variables, the hash number is optional. If it not present, the actions are carried out on hash 0.
|
Additional Information
Format Inheritable String Hashes (FISH) provide a mechanism for storing variables in a stack based system, with the ability to allow for inheritance of the values down through the stack. This is useful when processing data in a tree structure, i.e. XML, where the properties of an element need to be retained and inherited by its children.
For more information, see Technote 0087: Format Inheritable String Hashes (FISH).
Related Links