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Citat:Delphi Help:
The main source for a dynamically loadable library is identical to that of a program, except that it begins with the reserved word library (instead of program).
Only routines that a library explicitly exports are available for importing by other libraries or programs. The following example shows a library with two exported functions, Min and Max.
library MinMax;
function Min(X, Y: Integer): Integer; stdcall;
begin
if X < Y then Min := X else Min := Y;
end;
function Max(X, Y: Integer): Integer; stdcall;
begin
if X > Y then Max := X else Max := Y;
end;
exports
Min,
Max;
begin
end.
If you want your library to be available to applications written in other languages, it's safest to specify stdcall in the declarations of exported functions. Other languages may not support Delphi's default register calling convention.
Note
If your application includes VisualCLX components, you must use packages instead of DLLs or shared objects. Only packages can manage the startup and shutdown of the Qt shared libraries.
Libraries can be built from multiple units. In this case, the library source file is frequently reduced to a uses clause, an exports clause, and the initialization code. For example,
library Editors;
uses EdInit, EdInOut, EdFormat, EdPrint;
exports
InitEditors,
DoneEditors name Done,
InsertText name Insert,
DeleteSelection name Delete,
FormatSelection,
PrintSelection name Print,
...
SetErrorHandler;
begin
InitLibrary;
end.
You can put exports clauses in the interface or implementation section of a unit. Any library that includes such a unit in its uses clause automatically exports the routines listed the unit's exports clauses--without the need for an exports clause of its own.
The directive local, which marks routines as unavailable for export, is platform-specific and has no effect in Windows programming.
On Linux, the local directive provides a slight performance optimization for routines that are compiled into a library but are not exported. This directive can be specified for stand-alone procedures and functions, but not for methods. A routine declared with local--for example,
function Contraband(I: Integer): Integer; local;
does not refresh the EBX register and hence
cannot be exported from a library.
cannot be declared in the interface section of a unit.
cannot have its address taken or be assigned to a procedural-type variable.
if it is a pure assembler routine, cannot be called from another unit unless the caller sets up EBX.
Porgledaj malo help... sve je lepo i detaljno objasnjeno.
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