Thank you very much Ian!
I am using a pointer to the map because i want to pass the map by
reference, not by value.
Those maps can become pretty large and are being handed down through a
couple of function calls and i don't want them to be copied over and over
again.
I read the document you referenced, but am not able to understand…
So i can use interface{} or any just to generalize simple types?
Why is the compiler accepting then a p_Values map[string]interface{} as a
parameter of a function? - What would be a compatible data-type to pass as
this parameter?
Thank you very much in advance for your help.
Best regards from Charleston (WV),
Frank/2
Ian Lance Taylor schrieb am Dienstag, 14. März 2023 um 21:40:27 UTC-4:
> On Tue, Mar 14, 2023 at 6:27 PM Frank Jüdes <jue...@gmail.com> wrote:
> >
> > i still somewhat new with Go and need a little tutoring: I have to
> create Excel files, using the excelize package and wrote a little function
> to store data from a map[string]int64 into a column within the worksheet:
> >
> > //
> -------------------------------------------------------------------------------------------------
> > // Store a slice of int64 data items into the cells of a column
> > //
> -------------------------------------------------------------------------------------------------
> > func SetColumnValuesInt64(xf *excelize.File,
> > p_SheetName string,
> > p_StartRow int,
> > p_Column rune,
> > p_CellStyle *excelize.Style,
> > p_Keys *UTL_StringSlice.T_StringSlice,
> > p_Values *map[string]int64) {
> > Row := p_StartRow
> > StyleID,_ := xf.NewStyle(p_CellStyle)
> > for _,Key := range(*p_Keys) {
> > CellAddress := fmt.Sprintf("%c%d",p_Column,Row)
> > xf.SetCellValue(p_SheetName,CellAddress,(*p_Values)[Key])
> > xf.SetCellStyle(p_SheetName,CellAddress,CellAddress,StyleID)
> > Row++
> > } // END for
> > } // END SetColumnValuesInt64
> >
> > Basically the function iterates through a slice of strings, containing
> the key-values for the data-map and then calls the SetCellValue function
> from the excelize package to store the number into the cell.
> > Now i have another set of data, stored into a map[string]float64 …
> > So i duplicated the above function, just replacing the red line with
> > p_Values *map[string]float64) {
> >
> > Basically it is the same code, just the parameter-type is different. I
> looked into the definition of the function SetCellValue and saw that it is
> using the empty interface as parameter for the value, so i tried to define
> my function with
> > p_Values *map[string]interface{}) {
> >
> > The function compiles fine, but if i try to use it with a
> *map[string]int64 as a parameter, the compiler objectst with the message
> »cannot use Amounts (variable of type *map[string]int64) as type
> *map[string]interface{} in argument to ExcelFormats.SetColumnValues«
> >
> > Can somebody please give me hint what i am doing wrong?
>
> First I'll note that it's quite unusual to use a pointer to a map.
> Maps are reference types. If you pass a map to a function, and that
> function adds values to the map, the caller will also see the new map
> entries.
>
> That said, the error message seems clear enough: a function that
> expects a pointer to map[string]any can't take an argument that is a
> pointer to map[string]int64. The types any and int64 are different
> types. You can't interchange them. See
> https://go.dev/doc/faq#covariant_types for a related issue.
>
> Ian
>
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