On 2019-05-01 14:23:37 +0000, Alex said:
On Wednesday, 1 May 2019 at 12:47:22 UTC, Robert M. Münch wrote:
I use some C library that uses structs and many functions that use
pointer to structs as arguments:
struct A {...};
myfunc(A *myA);
In C you can do this to get a lvalue:
myfunc(&(A){...});
In D this doesn't work and I get an "is not an lvalue and cannot be modified".
What's the correct D-ish way in such a case?
Look, even in C you have to workaround the case, where you want to pass
a value instead of a pointer.
That's not a workaround in C, it's the way to do it.
However, to rebuild the same structure, auto ref parameters may be appropriate.
https://dlang.org/spec/template.html#auto-ref-parameters
That would need me to change myfunc which is not possible because the D
binding is all generated from C code.
or you new A(...) in place
Doesn't work because this seems to kick in some D releated run-time
stuff which lead to unresolved externals during linking:
error LNK2001: Nicht aufgelöstes externes Symbol "...__initZ".
error LNK2001: Nicht aufgelöstes externes Symbol
"...__xtoHashFNbNeKxSQBtQBoQBfZm".
error LNK2001: Nicht aufgelöstes externes Symbol
"...__xopEqualsFKxSQBsQBnQBeKxQmZb".
Not sure, why this happens.
or you use the byRef-pattern as shown in d-idioms
https://p0nce.github.io/d-idioms/#Rvalue-references:-Understanding-auto-ref-and-then-not-using-it
This again would need my to change the C bindings, which are generated.
--
Robert M. Münch
http://www.saphirion.com
smarter | better | faster
