[DUG]Scope

[Phil Middlemiss]

tbdata is a field of TForm1 so the code that uses it must have an 
instance of TForm1 to access tbdata.
So the code that uses it needs to have:

	    FormInstance.tbData.First;
	    while not FormInstance.tbData.eof do


etc.

John Bird wrote:
> This is my understanding of accessing variables and procedures and functions
> in other units and forms:
>
> Functions and Procedures I found summarised nicely in a post:
>
> "From: James Getz <supporti... at borland.com>
> Subject: Re: Calling a procedure in another form
>
>   The answer to your question depends on where you declare the function.
> If the function is declared as part of the form object, then you would use
> form.function (it is a method of the form class at that point) to access
> it.  If it's a freestanding function (not part of a class) then you would
> access it as unit.function."
>
> I have also found that if the other unit is in the uses clause, then a
> freestanding function or procedure does not even need the unit name - the
> compiler and linker can find it using the uses clause.  This is how I use a
> unit full of library procedures and functions, with just the procedure or
> function name.  Delphi also does this all the time, for example to find
> FieldbyName is defined in Delphi 2006 hovering over this statement reveals
> the tip "Declared in DB.TDataSet", and when using FieldbyName no unit prefix
> is required.
>
> Variables  - if declared in the interface section of say unit1, and unit2
> has a "uses unit1"  statement then unit2 can see these global variables in
> unit1.
>
> QUESTION:
>
> Now - I have moved some code from one unit to another and it won't compile
>
> Unit1 declares in the interface section
>
> type
>   TForm1 = class(TForm)
>     tbData: TClientDataSet;
>     DataSource1: TDataSource;
>     DBGrid1: TDBGrid;
>
>
> Unit2 declares
>
> implementation
>
> {$R *.dfm}
> uses Unit1,Unit3...etc;
>
>
> But statements in unit2 such as 
>
> 	    tbData.First;
> 	    while not tbData.eof do
> 	    begin
>             setfont('arial',8); 
> 	      printtab(tbData.fieldbyname('Field1').asString);
> 	      printtab(tbData.fieldbyname('Field2').asString);
>  	      printtab(tbData.fieldbyname('Field3').asString);
>  
>
> Are all giving errors about tbdata saying undeclared identifier and won't
> compile.  I am thinking Unit2 should be able to see tbData in Unit1.
> (I am trying to put some Rave Report code into a separate general printing
> routine so I can re-use it).
>
> John
>
>
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>
>
>   
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