betterC DLL in Windows
Adam D Ruppe
destructionator at gmail.com
Sun Feb 5 00:20:24 UTC 2023
On Saturday, 4 February 2023 at 18:40:51 UTC, Tamas wrote:
> I do take your word for it, but now I have to re-evaluate my
> expectations towards D and perhaps use it for another project.
> I've got most of my project working in C already, but I was
> hoping to add some safety and better readability/managability
> by using some of the convenient features D offers over C.
This is achieved without the betterC switch, and severely limited
> Also, your words give me the impression that I cannot trust the
> documentation; which isn't a great start into the learning
There's a lot of things described in the documentation that don't
actually work. D can be an *extremely* productive language if you
know which parts to focus on, but most the newer hyped features
just don't deliver.
The table of contents on the left side of the site is in roughly
chronological order. The things near the top are pretty reliable,
with a few exceptions (which are generally called out in the
documentation if you read it carefully, like how the "static
initialization of associative arrays" is "not yet implemented",
or misuse of shared is "is not an error yet by default").
The things near the bottom are not reliable. The C++ interface
works in some cases but you aren't likely to get far using it in
any real world project; the C++ stdlib bindings are extremely
minimal and Windows-only. The Objective-C interface works
beautifully on dmd.... which cannot target the new Apple devices.
ldc can generate code for those arm chips, but the Objective-C
interface is not implemented on ldc.
The portability guide and named character entities are pretty
The memory safety `@safe` stuff only actually works if you 1) opt
into it in the functions and 2) opt into it on command line
params. This is mentioned in the docs as a small note near the
bottom. The design of @safe also allows several things that can
escape it on certain systems.
The ABI page is ok, but there are several bugs in the debug info
output. I find it good enough but it can be annoying.
The vector extensions work on dmd if you can piece together the
magic but the other compilers do it differently.
The betterC page has several falsehoods on it, including the
misinformation that you need to use it to link into C
applications. This is just 100% nonsense. It also claims nearly
the full language remains available, but this is also simply
false. Some of the things listed there can be made to work with a
bunch of code, but many things just plain don't work, even if you
add the small amounts of code necessary to enable them.
For example, interfaces don't work, even if you implement your
own dynamic cast function. It just doesn't let them link. It
claims constructors and destructors work, which is true, unless
they're `static`, in which case you get random errors. Delegates
and lambdas work if you manage captured variables in your own
functors, but otherwise are simply disabled, even if you had your
own backing system.
Even module imports can fail because betterC disables outputting
the module data info, even if it would otherwise be required by
language rules, despite it not using the druntime.
Then importC only works for toy examples. Using two separate
headers or modules will result in spurious compile errors (and
bugs detailing how to address this have been closed WONTFIX), and
there's several kinds of C apis it just doesn't support.
And finally, the @live functions also only work in toy examples
and the design is fundamentally limited to only direct function
calls, no struct aggregation is supported at all. It is a
complete dead end.
On the other hand, if you avoid most the compiler switches and
stick to the more solid features - "Interfacing to C" and above
on the list, for the most part - you'll find D is a very capable
More information about the Digitalmars-d-learn