What exactly is the o. file?

[Danail]

So?

[Marc]

a .o file is a so called object file.
This file contains compiled code. FPC compiles every unit into a .o (and a .ppu, containing info needed for fpc). After compilation, all .o files get linked together through a linker (ld or the internal linker) into a executable.

[Danail]

Then can I use a the o. file of some of my units in another program. If I can, then how?

[abb]

Then can I use a the o. file of some of my units in another program. If I can, then how?

I'd look at the compiler directives. Borland pascal compilers have {$L} directive for object files linking. Hope Free Pascal also has similar directive. Please take a look at the docs.

HTH!

[Danail]

I used the {$L} option and the program compiled successfuly, so it is supported. However it remained to me unclear how to use the functions and the procedures there (in the linked o. file). Trying to call them provokes error.

[Bart]

Did you declare the functions you want to use from the .o file like

Code: [Select]

{$L someunit.o}
procedure foo; external;
This is the old TP style of linking in external object files.

Bart

[Marc]

And now the question.....
Why do you want to do this ?

[Danail]

It has many advantages. Now I can think out for two: you can use units without revealing your code; use code compiled with GCC and other languages creating o. files without even knowing the language that they are made.

[abb]

I used the {$L} option and the program compiled successfuly, so it is supported. However it remained to me unclear how to use the functions and the procedures there (in the linked o. file). Trying to call them provokes error.

Do you know the calling model type of your external procedure? May be it it is a C procedure? It's worth to know it.

[Danail]

Er... by the way does anyone know a java compiler that makes o. files?

[abb]

Er... by the way does anyone know a java compiler that makes o. files?

Offtopic....

Java COMPILER??? Java is not a compiler. It works a p-code, which Java RTE interpets and executes. This is the reason why Java is platform-independent.

[felipemdc]

If you want to convert java code to .o files, I would say you shouldn't be using Java in the first place.

[Marc]

Bewarned that you cannot export any class, ansistring or dynarray this way.

[Danail]

If the o. file is a readily compiled output, so it is supposed to be a platform dependant. So o. file compiled for windows may not be useful on Linux, Is it right?

[felipemdc]

If the o. file is a readily compiled output, so it is supposed to be a platform dependant. So o. file compiled for windows may not be useful on Linux, Is it right?

Yes, exactly.