Every problem can be solved by adding another level of indirection (except
perhaps having too many levels of indirection :-) ). You can put the code
below in a separate file:
(define (make-info-menu-item parent target-table)
(new menu-item%
(label "info")
(parent parent)
(callback (lambda (menu-item event)
(message-box "Info"
(~a "You have selected " (length (send target-table get-
selected-row-indexes)) " rows")
#f)))))
And use it like so:
(require "info-menu-item.rkt")
(define row-edit-menu (new popup-menu% ))
(define table3 ...)
(define info-menu (make-info-menu-item row-edit-menu table3)
You could also have just one "make-row-edit-menu" function which creates
all menu items.
Alex.
On Thursday, May 7, 2020 at 7:50:01 AM UTC+8, James Platt wrote:
>
> I'm working on organizing and documenting some things and I have some
> code, below, which works but I don't understand why. Specifically, why
> don't I get an error about table3 not being defined?
>
> This is a very simplified version of what I'm working on. What I actually
> want to do is put all the code related to creating a standard table editing
> menu in a file which I can then include wherever I want that menu. The
> full menu will be a lot of code. Unfortunately I can't seem to get this to
> work without either getting an error that row-edit-menu is not defined or
> that table3 is not defined. In other words, I want to be able to define
> table3 in one file which requires the file where row-edit-menu is defined
> but I can't seem to figure out how to get this to work. It works just fine
> when all the code is in one file, however.
>
> James
>
>
> #lang racket
> (require racket/gui/base
> qresults-list
> )
>
> ;set up columns
> (define (column1 data) (vector-ref data 0))
> (define (column2 data) (vector-ref data 1))
>
> (define my-columns
> (list
> (qcolumn "Column1" column1 column1)
> (qcolumn "Column2"
> (lambda (row)
> ;(displayln row)
> ;(displayln (db-row-ref row "Column2" headers 1))
> (if (number? (column2 row)) (number->string (column2 row))
> "");This allows a cell to be blank.
> ;(number->string (column2 row))
> )
> column2)
>
> )
> )
>
> (define frame3 (new frame%
> [label "myTable 3"]
> [width 800]
> [height 600]
> ))
>
>
> (define row-edit-menu (new popup-menu% ))
>
> (define info-menu-item (new menu-item%
> (label "info")
> (parent row-edit-menu)
> (callback (lambda (menu-item event)
> (message-box "Info"
> (~a "You have
> selected " (length (send table3 get-selected-row-indexes)) " rows")
> #f)
> ))
> ))
>
> (define table3
> (new (class qresults-list% (init) (super-new)
> [parent frame3]
> [pref-tag 'preferences-tag]
> [selection-type 'multiple]
> [right-click-menu row-edit-menu])
> )
>
> (send table3 setup-column-defs my-columns)
>
> (send frame3 show #t)
>
> (send table3 add-row (vector "R1C1" 10))
> (send table3 add-row (vector "R2C1" 11))
> (send table3 add-row (vector "R3C1" 12))
> (send table3 add-row (vector "R4C1" 13))
>
>
>
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