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digitalmars.D - Binding D to C

reply Walter Bright <newshound2 digitalmars.com> writes:
http://www.gamedev.net/page/resources/_/technical/game-programming/binding-d-to-c-r3122

http://www.reddit.com/r/programming/comments/1eerd9/binding_d_to_c/

https://news.ycombinator.com/newest
May 15 2013
next sibling parent Walter Bright <newshound2 digitalmars.com> writes:
On 5/15/2013 5:37 PM, Walter Bright wrote:
 http://www.gamedev.net/page/resources/_/technical/game-programming/binding-d-to-c-r3122


 http://www.reddit.com/r/programming/comments/1eerd9/binding_d_to_c/

 https://news.ycombinator.com/newest

er, https://news.ycombinator.com/item?id=5716098
May 15 2013
prev sibling next sibling parent reply "Mike Parker" <aldacron gmail.com> writes:
On Thursday, 16 May 2013 at 00:37:55 UTC, Walter Bright wrote:
 http://www.gamedev.net/page/resources/_/technical/game-programming/binding-d-to-c-r3122

 http://www.reddit.com/r/programming/comments/1eerd9/binding_d_to_c/

 https://news.ycombinator.com/newest

Thanks! I never received any notification that it was publicly accessible now. Just a note for anyone who's already read the blog series. This is the same material, just updated, corrected and edited together. Please prefer this to the blog posts when referring people to it.
May 15 2013
parent Paulo Pinto <pjmlp progtools.org> writes:
Am 16.05.2013 08:15, schrieb Mike Parker:
 On Thursday, 16 May 2013 at 00:37:55 UTC, Walter Bright wrote:
 http://www.gamedev.net/page/resources/_/technical/game-programming/binding-d-to-c-r3122


 http://www.reddit.com/r/programming/comments/1eerd9/binding_d_to_c/

 https://news.ycombinator.com/newest

Thanks! I never received any notification that it was publicly accessible now. Just a note for anyone who's already read the blog series. This is the same material, just updated, corrected and edited together. Please prefer this to the blog posts when referring people to it.

I enjoyed reading it, quite nice.
May 16 2013
prev sibling parent reply Jacob Carlborg <doob me.com> writes:
On 2013-05-16 02:37, Walter Bright wrote:
 http://www.gamedev.net/page/resources/_/technical/game-programming/binding-d-to-c-r3122


 http://www.reddit.com/r/programming/comments/1eerd9/binding_d_to_c/

 https://news.ycombinator.com/newest

It's a good article. I haven't read it completely to the end but I would like to mention a few things. You didn't mention macros, global variables or inline functions. I think I've seen inline functions somewhere. Global Variables Global variables need to have an extra "extern" and the __gshared storage. Example in C: int a; Translated to D: extern (C) extern __gshared int a; For TLS variables __gshared is not used. Typedefs When I do a binding I'm trying to figure out why they used a typedef in the first place. There's a couple of reasons: * To get a fixed type on all platforms. In the C language there are no fixed types, it's just relations between the sizes of the types. I.e. long => int => short => char, or something like that. In this case, use the native D type. In D a given type has a fixed size on all platforms (except for real). Examples of these can be: "int8_t", "uint16_t", "uint32_t" and so on. * To get different sizes on different platforms. For example, a 32bit value of 32bit platforms and a 64bit value of 64bit platforms. In this case you're basically forced to use an alias. * Opaque types. Perhaps the API is hiding the actual type behind a void* or for other reasons uses a void*. Then it uses a tyepdef on top of that to give it an idea of what type we're dealing with. In this case use the typedef. * The typedef is well known in the API. Examples of this would be GLint. I don't remember why they use typedefs but if I recall correctly GLint is used in all examples, tutorials, books and so on. In this case it's best to the typedef. * Hiding a complex type. An example of this could be function pointers. In this case use the typedef. Function pointers With function pointers there are (at least) two cases where an alias have to be used, instead of a function pointer. * When declaring function parameters with a specific linkage. The following is syntactically invalid in D: void foo (extern(C) void function () callback); Use an alias: alias extern (C) void function () Callback; void foo (Callback callback); * When using a cast with a specific linkage. You won't see this in a binding, if you're not converting inline functions. This is invalid in D as well: void* foo; ... auto bar = cast(extern (C) void function ()) foo; Use the same approach as above. Structs/Unions You actually didn't mention unions at all but basically all the same rules that apply when translating structs apply to unions as well. Two other things that you didn't mention was nested structs and anonymous structs. Structs * For named structs in typedefs I feel a bit undecided of how I want to have it. You can either just use the name of the typedef in D when declaring the struct. Or you can use the real name of the struct and then use an alias as well. In some cases the actual name of the struct could be used, i.e. "struct foo". Anonymous Structs * If an anonymous struct is used directly to declare a variable you're forced to invent a name for the struct in D, since D doesn't support anonymous structs. Example: struct { int a; int b; } c; Translate to: struct _AnonymousStruct1 { int a; int b; } _AnonymousStruct1 c; Any name can be used in this case. In my tool, DStep, for automatically generating bindings I'm using names similar to above. * If an anonymous struct is used in a typedef just use the name of the typedef. No alias is required in the D code in this case. I actual noticed now that you have this example. Nested structs I always fail to remember how these should be translated to D. * For nested structs that are named. Example: struct Foo { int a; struct Bar { int b; } bar; } In this case translate it to a named struct in D as well: struct Foo { int a; struct Bar { int b; } Bar bar; } * For nested struct that are anonymous. Example: struct Foo { int a; struct { int b; } bar; } In this case you could translate it to an anonymous struct in D as well: struct Foo { int a; struct { int b; } } The problem with this is that the API changes. Instead of accessing "b" like this: struct Foo foo; foo.bar.b = 1; You would do like this: Foo foo; foo.b = 1; I actually looked at the documentation now and see that this example is not used anymore: http://dlang.org/interfaceToC.html http://dlang.org/htod.html It's still on the D1 page: http://digitalmars.com/d/1.0/htomodule.html -- /Jacob Carlborg
May 17 2013
next sibling parent reply "Regan Heath" <regan netmail.co.nz> writes:
On Fri, 17 May 2013 08:44:14 +0100, Jacob Carlborg <doob me.com> wrote:

.. lots of great things.  Can we get all the advice from the article and  
these replies onto a D wiki or howto page pls.  If someone can point me to  
where to add it, I can do a rough copy/paste.  Assuming both authors are  
happy with this..

R

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May 17 2013
parent reply Jacob Carlborg <doob me.com> writes:
On 2013-05-17 10:46, Regan Heath wrote:
 On Fri, 17 May 2013 08:44:14 +0100, Jacob Carlborg <doob me.com> wrote:

 .. lots of great things.  Can we get all the advice from the article and
 these replies onto a D wiki or howto page pls.  If someone can point me
 to where to add it, I can do a rough copy/paste.  Assuming both authors
 are happy with this..

See if you can find an existing page here: http://wiki.dlang.org Or create a new one. -- /Jacob Carlborg
May 17 2013
parent Jacob Carlborg <doob me.com> writes:
On 2013-05-17 16:48, Regan Heath wrote:

 Done.
 http://wiki.dlang.org/Bind_D_to_C

Hmm. I see you just copy pasted my answer. It fits as an answer in a newsgroup like this. But I don't think it fits in that format in the wiki. -- /Jacob Carlborg
May 18 2013
prev sibling next sibling parent "Regan Heath" <regan netmail.co.nz> writes:
On Fri, 17 May 2013 13:53:20 +0100, Jacob Carlborg <doob me.com> wrote:

 On 2013-05-17 10:46, Regan Heath wrote:
 On Fri, 17 May 2013 08:44:14 +0100, Jacob Carlborg <doob me.com> wrote:

 .. lots of great things.  Can we get all the advice from the article and
 these replies onto a D wiki or howto page pls.  If someone can point me
 to where to add it, I can do a rough copy/paste.  Assuming both authors
 are happy with this..

See if you can find an existing page here: http://wiki.dlang.org Or create a new one.

Done. http://wiki.dlang.org/Bind_D_to_C Linked into: http://wiki.dlang.org/Tutorials (under How To) http://wiki.dlang.org/Bindings (under Binding D to C) R -- Using Opera's revolutionary email client: http://www.opera.com/mail/
May 17 2013
prev sibling parent "Regan Heath" <regan netmail.co.nz> writes:
On Sat, 18 May 2013 14:10:07 +0100, Jacob Carlborg <doob me.com> wrote:

 On 2013-05-17 16:48, Regan Heath wrote:

 Done.
 http://wiki.dlang.org/Bind_D_to_C

Hmm. I see you just copy pasted my answer. It fits as an answer in a newsgroup like this. But I don't think it fits in that format in the wiki.

That's what I said I'd do.. it's all I have time for. I think having the info there, even if it doesn't necessarily "follow" is better than not. Someone with more time can improve upon it. R -- Using Opera's revolutionary email client: http://www.opera.com/mail/
May 20 2013