[fpc-pascal] Pascal and static executable

[Jonas Maebe]

On 18 Jul 2011, at 10:03, ik wrote:

> Let's say that I write the following code:
> 
> program say_hello;
> 
> begin
>  writeln('Hello');
> end.
> 
> program say_helloworld;
> 
> begin
>  writeln('Hello World');
> end.
> 
> They both have the same size and the same memory footprint.
> So what exactly is going on ?

Alignment/rounding of section sizes.

> Why does Pascal compiler generate static
> linked executable while C/++ compiler will generate dynamic executable ?
> 
> What are the benefits in this approach and what are the bad things with it ?

With static linking, you can copy the program to other systems and it will normally just work. With dynamic linking, the target systems needs a version of the same dynamic library (or a compatible version for the program to run. The advantage of dynamic linking is that shared libraries can be loaded in memory just once, and then the same copy of the library can be used by all programs that link to it (with copy-on-write for writable sections of the data, so that programs won't influence each other when writing).

FPC's rtl interface is not very stable, so using a shared library approach would probably cause lots of compatibility problems (or require the installation of many different version of the FPC rtl shared library, with most programs using a different version). The interface of libstdc++ changes less often.


Jonas