Am 01.09.2010 23:58, schrieb José Mejuto:
Hello Lazarus-List,
Wednesday, September 1, 2010, 11:21:54 PM, you wrote:
FC> When you put a number of files in a package will the units that are not
used
FC> by compiled into the program?
If they do not have initialization or finalization sections, and no
functions are being used I think they are compiled but not linked in.
The initialization and finalization usually introduce non expected
code in the final program. Example, think in an unit like:
-------------------------------
unit DoNothing
uses someuses...;
type
TMyUselessObject=class(TObject);
T: TreeView;
end;
var
MyUselessObject: TMyUselessObject;
initialization
MyUselessObject=nil;
-------------------------------
The simple reference in the initialization pulls in all the code in
the unit related to TMyUselessObject even when you do not use
TMyUselessObject in you code. And as TMyUselessObject uses a TreeView
(in example) all the TreeView code is pulled in, which finally will
pull in almost all the LCL even if your code does not use LCL at all.
I'm quite sure about this, but maybe a more authorized voice can
confirm.
PS: I'm not sure about non referenced global arrays or variables :-?
Let's describe this a bit easier (without smartlinking):
All units in a package are compiled, but only units that are directly
(in uses clause of one of your project units) or indirectly (in uses
clause of a package unit which is used by your program) used by your
program are linked into the resulting binary.
Example:
You have a package that contains the following units:
- UnitA (uses no units of the package)
- UnitB (uses UnitC)
- UnitC (uses no units of the package)
- UnitD (usen no units of the package)
Now you have a program that uses the units UnitA and UnitB. Thus the
units UnitA, UnitB and UnitC are linked into your program, but UnitD is not.
Don't interpret to much "magic" into the packages of Lazarus. It's the
same as a unit search path, but automatically managed by the IDE and
only compiled if needed.
Is it clear now?
Regards,
Sven
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