Writing a library

[David Gileadi]

Mn wrote:
> David Gileadi Wrote:
> 
>> Jarrett Billingsley wrote:
>>> "Mn" <mn at mailinator.com> wrote in message 
>>> news:er492f$1sti$1 at digitalmars.com...
>>>> Hello World!
>>>>
>>>> Is it possible to write a library in D that can be used by other 
>>>> programming languages? And if yes, how to do it? I can think of two ways 
>>>> of "using" a lib in general:
>>>>
>>>> 1. The OOP way: use a class of the lib, then its functions, dunno how its 
>>>> called.
>>>> 2. The Un-OOP way: use a function of a lib, its called P/Invoke in C#.
>>>>
>>>> I am only interested in the more popular languages like C, C++, Java, C#, 
>>>> PHP.
>>>>
>>>> Greetings and thank you.
>>>> -- Mn
>>> No other languages understand D calling or mangling conventions, but D can 
>>> make functions with C, Windows, and Pascal calling conventions.  If you just 
>>> do something like:
>>>
>>> extern(C) export void func(int x) { ... }
>>>
>>> You can then, maybe, make a DLL or something out of it which can be called 
>>> from virtually any other mainstream language, since most things understand 
>>> the C calling convention. 
>>>
>> I tried this very thing about a year ago, creating a DLL in D with 
>> extern(C) functions which was imported and called by a C# program.  It 
>> passed data back and forth via simple structs, defined on both the C# 
>> and D side.  It worked great when called via a D host, but would 
>> segfault every time I tried it from the C# host.  I never did figure out 
>> what was going on (and since it was a school project I just gave up and 
>> ported the code to C#).  I suspected it was the fault of the garbage 
>> collector running in a separate thread, and at the time the calls to 
>> disable/enable the GC didn't do anything, so I didn't get to test if my 
>> suspicion was true.
>>
>> I'd be very interested to hear of your success with this.
> 
> You said you wrote a DLL in D and tried to access it via C#, ok. But what do you mean with "D host" and "C# host" then?? Accessing a .NET Assembly is unlikely to be possible that easy from D, although C# offers COM support. I will post a seperate reply for this topic.
> 
> As far as I know there is a way to disable GC for parts of or the whole program.
> 
> I will of course continue to look into this, but as of now I just started with D. Although it looks wonderful and its steep learning curve should be conquered in zero time.

Maybe "host" wasn't the best choice of words.  I meant the .exe which 
loads the DLL and calls the code--i.e. in this case the C# program was 
the "host".  I also had a program written in D to call the code in the 
DLL.  I never tried to load a DLL written in C# from D code--as you say, 
this is not likely possible, at least not without some massive effort.