Anything defined in the interface section of a unit is visible and callable from another unit that uses that unit. This includes Types, Constants, Classes, Functions, and Procedures. You should simply add the unit's name you want to use to the uses clause of the unit you wish to use it from. Unless necessary, you should define the uses clause in the implementation section, to help avoid circular reference errors. This is where two units depend on each other in their interface sections.

If you have a function in the current unit that has the same name as a function in another unit your wish to call, you can preface the function name with the unit name to fully qualify it.

The following example demonstrates calling functions and procedures and accessing variables in another unit:

Example:

{Code for unit2}

unit Unit2;

interface

procedure SomeProcedure(i : integer); function SomeFunction(i : integer) : integer;

var SomeInteger : integer;

implementation

procedure SomeProcedure(i : integer); begin SomeInteger := i; end;

function SomeFunction(i : integer) : integer; begin Result := SomeInteger; SomeInteger := i; end;

end. {Code for unit 's implementation section:}

implementation uses Unit2;

{$R *.DFM}

procedure TForm .Button Click(Sender: TObject); begin SomeProcedure( 0); ShowMessage(IntToStr(SomeFunction( 2))); ShowMessage(IntToStr(SomeInteger)); end;

procedure TForm .Button2Click(Sender: TObject); begin {Lets do the same thing as Button Click but fully qualify the names} Unit2.SomeProcedure( 0); ShowMessage(IntToStr(Unit2.SomeFunction( 2))); ShowMessage(IntToStr(Unit2.SomeInteger)); end;

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