What happens when you launch a D application ?

[John Colvin via Digitalmars-d-learn]

On Friday, 22 May 2015 at 11:51:01 UTC, John Colvin wrote:
> On Friday, 22 May 2015 at 11:13:43 UTC, Suliman wrote:
>> Am I right understand that that:
>> 1. every App start from main()
>> 2. Dmain is function that run after main is started and it's 
>> run GC, unit-tests and so on?
>
> Not really, it depends what you mean by main, the function 
> called main that you write in your source code or the function 
> called main that ends up in the actual program?
>
> Here's an example:
>
> int a;
>
> static this()
> {
>   a = 4;
> }
>
> void main() //
> {
>   a = 5;
> }
>
> Conceptually speaking, the compiler turns this in to:
>
> int a;
>
> extern(C) int main()
> {
>     a = 4;
>     return _Dmain();
> }
>
> int _Dmain()
> {
>     a = 5;
>     return 0;
> }
>
> I think that in practice it's more like this:
>
> int a;
>
> void staticConstructor1()
> {
>     a = 4;
> }
>
> //actually in druntime
> int _d_run_main(int function() sourceCodeMain)
> {
>     staticConstructor1();
>     // and all the other necessary setup
>     // for the program and runtime
>
>     sourceCodeMain();
> }
>
> extern(C) int main()
> {
>     _d_run_main(&_Dmain);
> }
>
> int _Dmain
> {
>     a = 5;
>     return 0;
> }

Give or take a few return statements, not that it matters.