MOL (Marek Olszewski)

Contributed samples by MOL (Marek Olszewski)


Billing System ( definable buttons )


Copy To Clipboard

Deactivate menu

Debug Message

Download from www

EAN13 BarCode Generator

Filter in Browse

HMG with MS SQL server

Incremental Search in BROWSE 

Menu like ACHOICE

Moldruk (Print like DOS )

Set Status Bar Item

Send mails via SMTP

Using ProgressBar as a graph



  STAGFIELDS() Tag fields

  aTagged => an array of element #'s of the tagged items


  Tags selected items in an array of fields, returning
  an array of element #'s of tagged items in the array of fields.

  [aFieldNames] - an array of field names. Default -
  all fields

  [cTitle]      - title for the popup. Default none

  [cMark]       - character used to mark as tagged.

                          Default is checkmark chr(251)

   aTagged := STAGFIELDS()

   for i = 1 to len(aTagged)

     ?field(aTagged[i])   // fieldname




Coding Guidelines

Coding Guidelines

( by Greg Holmes )

Language Syntax 
The general rule of thumb is: built-in features in lowercase, and custom-written functions in mixed case. 
When specifying the complete syntax of a language element in documentation, the input items, parameters, and so on are referred to using the following symbols:

 Symbol  Description
< >  Indicates user input item
( )  Indicates function argument list
[ ]  Indicates optional item or list
{ }  Indicates code block or literal array
| |  Indicates code block argument list
–>  Indicates function return value
 Repeated elements if followed by a symbol
Intervening code if followed by a keyword
,  Item list separator
|  Indicates two or more mutually exclusive options
@  Indicates that an item must be passed by reference
*  Indicates a compatibility command or function

For example:

    len(<cString>|<aArray>) --> nLength

Metasymbols provide a place holder for syntax elements, and they describe the expected data types. A metasymbol consists of one or more lowercase data type designators followed by a mixed case description. This is known as Hungarian Notation.

 Designator  Description
a  Array
b  Code block
c  Character expression
d  Date expression
exp  Expression of any type
id  Literal identifier
l  Logical expression
m  Memo field
n  Numeric expression
o  Object
x  Extended expression

In this example, dnLower and dnUpper can be either date or numeric:

    @...get...range <dnLower>, <dnUpper>
Filenames and Aliases 
All filenames, in any context, are in upper case. Filenames follow DOS naming conventions (preferably limited to letters, numbers, and the underscore).

    use CUSTOMER
    nHandle := fopen('DATAFILE.DAT')

When referring to specific file types in documentation, include the period.
e.g. “A program is stored in a text file with a .PRG extension.” 
Alias names follow the same conventions as filenames, but are limited to A-Z, 0-9, and the underscore. If a filename begins with a number or contains unusual characters, an alias must be specified when the file is opened or an error will result. 
Note that CA-Clipper does not natively support Windows 95 long filenames, although third-party libraries are available to add the capability.

Fieldnames are all uppercase, and always include the alias of the table. Fieldnames may contain underscores, but should not begin with one (because the underscore is generally used to indicate an internal symbol).

    @ 10, 10 say BANKS->BRANCH
Memory Variables 
Memory variables consist of a lowercase type designator followed by a mixed case description (see Hungarian Notation). Although CA-Clipper only recognizes the first 10 characters as unique, variable names may be longer.

    cString := "Hello World"
    nYearlyAverage := CalcYearAvg()

If you use Hungarian Notation for your memory variable names and include the table alias with fieldnames, there will be no conflict between the two.

Commands, Functions, and Keywords 
All built-in commands, functions, and keywords are lowercase. In documentation, the font should be Courier or a similar font. If fonts are not available, then bold or CAPITALIZE the word for emphasis. 
Never use abbreviations — this practice is not necessary with a compiler, although it was common in the early days of dBase (which was an interpreter). 
There should never be a space between the function name and the opening parenthesis. Also, note that the iif() function should never be spelled if().

    replace CUSTOMER->CUSTNAME with cCustName
    nKey := inkey(0)

When specifying commands that have clauses in documentation, separate the keywords with an ellipsis (...) and do not include the to clause, unless it is followed by the file,print, or screen keywords.

Programmer-Defined Functions & Procedures 
These begin with an uppercase letter, followed by mixed case letters as appropriate.

    ? StripBlanks("Hello there, this will have no spaces.")

Function and procedure names may contain underscores, but should not begin with one (they may conflict with internal functions which often start with an underscore). There should be only one return statement per function or procedure, and it should not be indented.

    function SomeFunc (...)
      . <statements>
    return cResult

The return value of a function is not enclosed in parentheses, although parentheses may be used to clarify a complex expression.

    return nValue
    return (nCode * 47) + nAnswer
Preprocessor Directives 
Preprocessor directives are lowercase and are preceded by the # sign.

    #include 'INKEY.CH'

Optionally, you may use single quotes around header files that come with CA-Clipper and double quotes around your own. This convention is purely voluntary, but it helps to distinguish between the two. For example:

    #include 'INKEY.CH'
    #include "MY_APP.CH"

Manifest constants are uppercase.

    #define ESCAPE   27
    if lastkey() == ESCAPE

Pseudo-function names should also be uppercase.

    #define AREA(length, width)   ((length)*(width))
Local variables are grouped according to functionality, and may be declared on one or more lines. The declarations appear as the first code at the beginning of a function or procedure.

    procedure Main ( )
    local nTop, nLeft, nBottom, nRight
    local cOldScreen, cOldColor, nOldCursor

Variables may be declared one per line and accompanied by a description.

    local nCount        // Number of records found.
    local nTotal        // Sum of dollars.

The description can be omitted if better variable names are chosen.

    local nRecordCount
    local nDollarTotal

Variables can be initialized when they are declared, although it is often clearer (and safer) to initialize them immediately before they are used.

    local nRecordCount:=0
    local nDollarTotal:=0
The .T. and .F. are typed in uppercase.
The in-line assignment operator (:=) is used for all assignments, and the exact comparison operator (==) is used for all comparisons.

    lContinue := .T.
    nOfficeTotal := nRegionTotal := 0
    lDuplicate := (CUSTFILE->CUSTNAME == cCustName)
    if nLineCount == 4  ...
    if left(PRODUCT->CODE, 3) == left(cProdCode, 3)  ...

Although the compound assignment operators (+=-=*=, etc.) are convenient, they should not be used if readability suffers.

    // The traditional way to accumulate:
    nTotal := nTotal + INVDETAIL->PRICE
    // A good use of a compound assignment operator:
    nTotal += INVDETAIL->PRICE
    // But what does this do?
    nVal **= 2

The increment (++) and decrement (--) operators are convenient, but can lead to obscure code because of the difference between prefix and postfix usage.

    nY := nX-- - --nX        // Huh?
Whenever a list of two or more items is separated by commas, the commas are followed by a space.

    MyFunc(nChoice, 10, 20, .T.)

Spaces may be used between successive parentheses.

    DoCalc( (nItem > nTotal), .F. )
    cNewStr := iif( empty(cStr), cNewStr, cStr + chr(13) )

Spaces should surround all operators for readability.

    nValue := 14 + 5 - (6 / 4)

In declarations, often spaces are not used around the assignment operator. This tends to make searching for the declaration of a variable easier.

    local lResult:=.F., nX:=0

Thus, searching for “nX :=” would find the lines where an assignment is made, while searching for “nX:=” would find the declaration line (such as the local above).

Indenting control structures is one of the easiest techniques, yet it improves the readability the most. 
Indent control structures and the code within functions and procedures 3 spaces.

    procedure SaySomething
       do while .T.
          if nTotal < 50
             ? "Less than 50."
          elseif nTotal > 50
             ? "Greater than 50."
             ? "Equal to 50."

Case statements in a do…case structure are also indented 3 spaces.

    do case
       case nChoice == 1
          ? "Choice is 1"
       case ...
Do not use tabs in source code — insert spaces instead. Tabs cause problems when printing or when moving from one editor to another, because of the lack of a standard tab width between editors and printers. Typically, printers expand tabs to 8 spaces which easily causes nested control structures to fall off the right-hand side of the page. Commonly, a source code editing program will insert the appropriate number of spaces when the <TAB> key is hit.
Line Continuation 
When a line of code approaches the 80th column, interrupt the code at an appropriate spot with a semicolon and continue on the next line. Indent the line so that it lines up in a readable manner.

    set filter to CUSTFILE->NAME  == 'John Smith  ';
            .and. CUSTFILE->STATE == 'OR'

To continue a character string, end the first line with a quote and a plus sign and place the remainder on the next line. Try to choose a logical place in the string to break it, either at a punctuation mark or after a space.

    @ 10, 10 say "The lazy brown fox tripped over " + ;
                 "the broken branch."
Use double quotes for text that needs to be translated (will appear on the screen), and single quotes for other strings.

    ? "Hello World!"
    cColor := 'W+/B'

This is a simple but extremely effective technique because translation departments often want to see the messages in context (in the source code), so the different quote types indicate which messages are to be translated and which should be left alone.

Comments are structured just like English sentences, with a capital letter at the beginning and a period at the end.

    // Just like a sentence.
    /* This comment is longer. As you
       can see, it takes up two lines */

You may encounter old-style comment indicators if you maintain older (Summer’87 and earlier) code.

    && This is an older-style of comment indicator.
    *  The asterisk is also old.

For in-line comments, use the double slashes.

    use CUSTOMER            // Open the data file.
    goto bottom             // The last record.

Note that the ‘//‘ of in-line comments begins at column 40, if possible. This leaves enough room for a useful comment.

Source :

Basic Controls – 3

( Status Bar, Check Box )

We are continuing with Viva_HMG.hbp, Main.prg and Main.fmg.

While using a table and while navigating between its records, we need some extra info to show to user: Name of table, current record and record count in the table. So user always feels comfortable by knowing where is he / she; which table, which record?

The status bar control is convenient for this purpose and though this is a quite simple control, IDE has a builder for it: Status bar builder.

When you choose this builder ( after open the .fmg file by IDE of course ), a dialog box will open:

By using this dialog box we can define a status bar. We can prefer define status bar manually too:

        STATUSITEM "" WIDTH 300
        STATUSITEM "" WIDTH 40
        DATE         WIDTH 90
        CLOCK             WIDTH 90

After define status bar, we need assign values to its items. We don’t need assign values to DATE and CLOCK items, because these items will be updated by system (HMG) automatically.

First a little procedure :


EditReco.StatusBar.Item( 1 ) := cTableFNam


RETURN // InitEdit()

Change ON INIT event of  EditReco form from ReadData() to InitEdit(.

And add this line at end of ReadData() procedure.

 EditReco.StatusBar.Item( 2 ) := LTRIM( STR( RECN() ) ) + "\" + ;
                                 LTRIM( STR( LASTREC() ) )

Let’s look at the result :

Whenever active record change, Item( 2 ) of Status Bar will be updated ( 5/25 ) in above picture.

In this step, user must use “Save” button every time current record edited.  Whereas “Read” process is different; whenever current record changed, values of text boxes automatically updated. What about automatic save? May be, we can do this; but user may don’t want such automation. Asking a question like “Do you want save?” every change doesn’t a good way.

The better way may be: put a control to form such “Auto save” with On / Off option.

Yes, fortunately we have such control: Check Box.

We can replace a Check Box control to EditReco form with chbAutoSave name and Auto Save caption:

Now, how we will implement Auto Save process?.

By adding a little IF clause to ACTION events of navigation buttons:

Top : (IF(EditReco. chbAutoSave.Value , SaveData(), ), DBGOTOP(), ReadData() )

Next : (IF(EditReco. chbAutoSave.Value , SaveData(), ), DBSKIP(), ReadData() )

Previous : ( IF(EditReco. chbAutoSave.Value , SaveData(), ), DBSKIP( -1 ), ReadData() )

Last : (IF(EditReco. chbAutoSave.Value , SaveData(), ), DBGOBOTTOM(), ReadData() )

To be continued …

Download source files

Message multiple values

MsgMulti ( aka MsM) is a message function accept multiple and any type of data.

Download here ( source only ).

StatusBar Control

HMG Tutor 19

Showing Status (Statusbar Control)

This control creates a bar at window’s bottom, used to show information (usually status information)

#include ""
Function Main
   AT 0,0 ;
   WIDTH 400 ;
   HEIGHT 200 ;
   TITLE 'Tutor 19 StatusBar Test' ;

      POPUP '&StatusBar Test'
         ITEM 'Set Status Item 1' ACTION ;
               Win_1.StatusBar.Item(1) := "New value 1"
         ITEM 'Set Status Item 2' ACTION ;
               Win_1.StatusBar.Item(2) := "New value 2"

      STATUSITEM "Item 1" ACTION MsgInfo('Click! 1')
      STATUSITEM "Item 2" WIDTH 100 ACTION MsgInfo('Click! 2')
      STATUSITEM "Item 5" WIDTH 100




HMG Tutor 7 — More Choices

HMG Tutor 7

More Choices

There is various alternatives to get an user’s choice besides RadioGroup.

One of them is the ListBox Control

@ 10, 10 LISTBOX List_1 ITEMS {'Option 1','Option 2','Option 3'}

Using a Listbox, you can add, change or remove items at runtime.

#include ""
Function Main
   AT 0,0 ;
   WIDTH 400 ;
   HEIGHT 200 ;
   TITLE 'Tutor 07 - ListBox Test' ;
      POPUP "First Popup"
         ITEM 'Change ListBox Value' ACTION ;
               Win_1.List_1.Value := 2
         ITEM 'Retrieve ListBox Value' ACTION ;
               MsgInfo ( Str(Win_1.List_1.Value))
         ITEM 'Add List Item' ACTION ; 
               Win_1.List_1.AddItem ('New List Item')
         ITEM 'Remove List Item' ACTION ;
               Win_1.List_1.DeleteItem (2)
         ITEM 'Change List Item' ACTION ;
               Win_1.List_1.Item (1) := 'New Item Text'
         ITEM 'Get List Item Count' ACTION ;
               MsgInfo (Str(Win_1.List_1.ItemCount))
   @ 10, 10 LISTBOX List_1 ITEMS {'Option 1','Option 2','Option 3'}

Main Menu

HMG Tutor 2

Adding The Main Menu

We add a main menu to the program now:

#include ""
Function Main
   AT 0,0 ;
   WIDTH 400 ;
   HEIGHT 200 ;
   TITLE 'Tutor 02 - Main Menu Test' ;
      POPUP "First Popup"
         ITEM 'Change Window Title' ACTION  Win_1.Title := 'New Title'
         ITEM 'Retrieve Window Title' ACTION  MsgInfo ( Win_1.Title )

As you can see it is pretty easy and intuitive.

All the main menu stuff will be between DEFINE MAIN MENU / END MENU statements.
Each individual menu popup will be between POPUP / END POPUP statements.
Each individual menu item will be coded via the ITEM statement.

You can use as popups as you need and you can nest it without any limit.

By the way, another handy feature, a Message function used here :

The MsgInfo() Function

This is a very useful function. It will show a little message window (with the system information icon) and a message (character type) passed as parameter.

You can optionally add a title (passed as the second parameter).

Note: By nature, Message function uses options in local language. Here “Tamam” means “Ok” in my language ( Turkish).