Element <flow>

The <flow> element is used to alter the natural execution sequence of IsisScript instructions. It allows creating conditional jumps (jump), terminating execution (exit), or controlling loop iterations (skip).

The specific behavior is determined by the action attribute and the content (argument) of the element.

Usage

• Allowed content: <pft> (defining the argument for the action).
• Parent elements: <do>, <function>, <hl>, <loop>, <section>, <update>

Syntax

<flow action="...">
    </flow>

Attributes

Attribute	Description
action	Required. Defines the type of flow control (exit, jump, skip).

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Action Details

action="jump" (GOTO)

Branches the execution of IsisScript to the corresponding <label> element.

• Argument: The name of the target label.

<flow action="jump">
    <pft>if p(v1) then 'GO' fi</pft>
</flow>

<label>GO</label>

action="exit"

Terminates the execution of the current IsisScript immediately.

• Argument: A numeric return code passed back to the operating system.

<flow action="exit">1</flow>

action="skip"

Controls the flow within a loop or scope. Its behavior depends strictly on the argument provided (Next or Quit).

• **Argument Next**: Branches execution to the beginning of the current <loop> (starts the next iteration). Equivalent to continue in C/PHP.
• **Argument Quit**: Abandons the current scope entirely and returns to the previous scope (breaks the loop). Equivalent to break in C/PHP.

Example: Conditional Loop Control In this example, the script skips to the next record if field v24 is absent. If field v26^c is greater than 1989, it stops the loop entirely.

<do>
   <parm name="db">CDS</parm>
   <loop>
      <flow action="skip">
         <pft>
            if a(v24) then 
               'Next' 
            else 
               if val(v26^c) > 1989 then 'Quit' fi 
            fi
         </pft>
      </flow>
      
      <display><pft>@CDS.PFT</pft></display>
   </loop>
</do>