Difference: PUSHPOPILFStatements (9 vs. 10)

Revision 102008-06-18 - JeffPrentice

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META TOPICPARENT	name="APPX43Features"

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New ILF Statements

Application designers gain more control through these new ILF statements.

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The TYPE field is used to specify either FIELD or RECORD, and load/retrieve accordingly. Scanning on the TYPE field displays six possible values (FIELD, DEFAULT FIELD, ORIGINAL FIELD, RECORD, DEFAULT RECORD, ORIGINAL RECORD), apparently because the structure of the statement was taken from the STORE/RESTORE statements. However, it is important to note that there is only one stack for each FIELD, and one for each RECORD; therefore specifying DEFAULT FIELD or ORIGINAL FIELD is no different than specifying FIELD. Note, though, that an error will occur if you specify ORIGINAL FIELD on something other than the Process Control File.

The POP statement retrieves values in the reverse order that they were PUSHED, i.e. a LIFO function, and returns a TRUE flag if a value was successfully POPped, and a FALSE flag if the stack was empty. There is no automatic way to empty a stack, other than to repeat the POP statement in a loop until it returns a FALSE.

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A sub-string field and a synonym field will each have their own stack. This is because the field names in the data dictionary are unique. A field with multiple occurrences will have one stack. For example, a field named MYFILE FLD is defined with 2 occurrences. If you pushed MYFILE FLD (001) then pushed MYFILE FLD (002) the data will be saved in the stack named MYFILE FLD. To retrieve the saved values you would POP MYFILE FLD twice. The first POP would return MYFILE FLD (002), the second POP would return MYFILE FLD (001) as described above.

An ideal use for PUSH and POP is to load virtual keystrokes (user options) into a stack, and have them executed automatically and sequentially. See the section on SELECT below for an example of this usage.

SELECT

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