[Libssh] Enhancements proposals

[Rodolphe Rocca]

Aris Adamantiadis wrote:
> Rodolphe Rocca a écrit :
>> Aris Adamantiadis wrote:
>>> Rodolphe Rocca a écrit :
>>>> On Wed, 27 Feb 2008 23:38:02 +0100
>>>> Aris Adamantiadis <aris at 0xbadc0de.be> wrote:
>>>>
>>>> Are you sure you want to switch to a C++ version ? I mean, libssh has
>>>>  already a good OO design in C, it is not so far from a _very good_
>>>> OO design. Furthermore, there is the classical argument in favor of C :
>>>> everything can link to it. Personnally I don't see a very strong reason
>>>> for a protocol library to use C++.
>>> The ease of development ? Doing a good OO design is C is nearly 
>>> impossible. There is no inheritence, no virtual methods,... 
>> Off course I wasn't talking about strict OO but more of using OO 
>> notation as in the linux kernel or many C libraries (cairo, gnutls are 
>> very good examples of this). A big part of libssh already uses 00 
>> notation, I was just talking about making libssh use OO notation everywhere.
>>
>> However I understand that C++ allows for much cleaner design than C.
>>
>>> look at the 
>>> mess in error.c to support inheritence (ssh_set_error that works on two 
>>> datastructure) and the mess in crypt.c to support virual methods.
>> Are you talking about multiple #ifdef ? I agree it's not the cleanest 
>> thing ever. However libssh could probably integrate a much cleaner 
>> crypto backend framework along with a libcrypto and libgcrypt backends.
>>
> Not really, i'm talking about the C structure, the function pointers in 
> it, the functions that try to mimic virtual methods and inheritence.

Ok I did not see those function pointers.

>>> C and C++ are completely compatible : it's easy to build a C stub which 
>>> runs the C++ methods behind.
>> Well I know that C is compatible with C++, but not C++ with C, unless by 
>> using very complex technics. So I'm very curious how you would do your 
>> stub in such a way that any native C library could compile and link 
>> against it.
> Just compile with g++ a code like
> extern "C" {
>   struct my_c_struct {
>      myClass *c;
>   };
>   int C_function_do_this(struct my_c_struct *this, int arg){
>     return this->c->do_this(arg);
>   }
> }
 > it works, I've tested it.

Yes, if you compile with g++. Are you sure a native C library (compiled 
with gcc) will be able to link to such object file containing C++ data 
structures ? I'm quite perplex.

>> And even if it's possible, you'll still have to design your C API...
> that's right. It will follow the external C++ api. But it's much less 
> hasle than having to design the whole code with these tricks.
>> Notice that I don't have any personal interest in keeping C for libssh : 
>> my application is written in C++. However I'm seriously thinking about 
>> the wide amount of applications written in C that could not use libssh.
>>
> or the applications that won't want to use libssh because it's C++ and 
> c++ is the root of all evil. Bad for them.

It's not my case :-)

> The only industry that will prefer the C version for good reasons is the 
> embedded industry. I think they can use the 0.2* versions because they 
> won't need the 0.3 features.

So you're telling them to use a deprecated unmaintained version... maybe 
some will stick to a version they're already using, but I doubt any 
company would get interested in starting with an already unmaintained 
library.

Rodolphe