isCOBOL Evolve : Language Reference : Procedure Division Statements : DESTROY
DESTROY
Format 1
DESTROY { Screen-Name-1 } ... [ UPON Screen-Group ]
        { Handle-1      }
Format 2
DESTROY ALL CONTROLS
Format 3
DESTROY CONTROL
Remaining phrases are optional, can appear in any order.
  AT Screen-Location
 
  AT LINE NUMBER Line-Num [CELL  ]
                          [CELLS ]
                          [PIXEL ]
                          [PIXELS]
 
  AT {COLUMN  } NUMBER Col-Num [CELL  ]
     {COL     }                [CELLS ]
     {POSITION}                [PIXEL ]
     {POS     }                [PIXELS]
Syntax rules
1. Screen-name-1 is the name of a screen description entry found in the Screen Section.
2. Handle-1 is a USAGE HANDLE or PIC X(10) data item.
3. Screen-location is an integer data item or literal that contains exactly 4 or 6 digits.
4. Line-num and col-num are numeric data items or literals. These may contain non-integer values.
5. Screen-group is a group item in Screen Section, so a Screen-name that is not associated to a control-class.
General rules
Format 1
1. The DESTROY verb clears the screen of active controls and removes the assigned handle(s) from memory and sets the value to binary zeroes.
2. If Handle-1 refers to a sub-window, the result is the same as a CLOSE WINDOW, causing all controls on that window to be DESTROYed. All child windows are also DESTROYed.
3. If Handle-1 is a handle of a menu or layout manager, the controlling window should be DESTROYed before the handle
4. The DESTROY verb as no effect on the main window, that is destroyed only when the runtime terminates.
5. If Handle-1 is a handle of bitmap or menu, the DESTROY verb has no effect. Use WBITMAP-DESTROY to destroy a bitmap handle and WMENU-DESTROY to destroy a menu handle.
6. If Handle-1 is a handle of one of the system pre-defined font (fixed-font, traditional-font, default-font, small-font, medium-font or large-font) the DESTROY verb has no effect.
7. If the UPON clause is followed by a Screen-group, the item is removed from that group and the screen is updated to reflect the change.
Format 2
1. DESTROY ALL CONTROLS destroys all controls created for the current window.
Format 3
1. Format 3 DESTROY uses the LINE/COLUMN phrases to indicate which control to DESTROY.
Examples
Format 1 - Destroy a screen.
display input-screen-1
perform until esc-pressed
  accept input-screen-1
end-perform
destroy input-screen-1
Format 1 - Destroy window.
display initial  window 
        screen line 10 screen column 10
        size 40.0 lines 25.0
        cell width 10 cell height 10
        title "Customer Information"
        handle cust-win-handle
...
destroy cust-win-handle
Format 3 - Destroy controls by line and col position.
display entry-field line 5.0 col 20.0
display label line 5.0 col 3.0 title "Customer code: "
...
destroy control line 5.0 col 3.0
destroy control line 5.0 col 20.0