28.10.2012 23:52, Artie пишет:
I have a DLL with a C++ class and a factory function that creates it.
The aim is to load the DLL, get an instance of the class and use it.
The interface of the DLL is as follows:
-----------------
class IBank
{
public:
virtual const char* APIENTRY getLastError() = 0;
virtual const char* APIENTRY getDetail(char* detail) = 0;
virtual const bool APIENTRY deposit(unsigned long number,
double amount) = 0;
virtual const bool APIENTRY withdraw(unsigned long number,
double amount) = 0;
virtual const double APIENTRY getBalance(unsigned long number)
= 0;
virtual const bool APIENTRY transfer(unsigned long numberFrom,
IBank* bankTo, unsigned long numberTo, double amount) = 0;
virtual const bool APIENTRY transferAccept(IBank* bankFrom,
unsigned long numberTo, double amount) = 0;
};
-----------------
I've followed the instructions given at dlang.org to interface to C/C++
code but got no success. If I use extern(C++) at the place in D code
where extern declaration is required I get an access violation when
calling any method. On the other hand, if I use extern(Windows, C or
Pascal) I can call a method successfully, except that I get wrong return
value.
The D interface is declared as follows:
-----------------
extern (Windows) interface IBank
{
const char* getLastError();
const char* getDetail(char* detail);
const bool deposit(uint number, double amount);
const bool withdraw(uint number, double amount);
const double getBalance(uint number);
const bool transfer(uint numberFrom, IBank* bankTo, uint numberTo,
double amount);
const bool transferAccept(IBank* bankFrom, uint numberTo, double
amount);
}
export extern (C) IBank Get();
-----------------
And the main program in D that uses the DLL:
-----------------
module main;
import std.stdio;
import core.runtime;
import core.sys.windows.windows;
import std.string;
import std.conv;
import ibank;
int main()
{
alias extern(C) IBank function() getBankInstance;
FARPROC pDllFunctionVBank, pDllFunctionSberbank;
// Load DLL file
void* handleVBank = Runtime.loadLibrary("vbank.dll");
void* handleSberbank = Runtime.loadLibrary("sberbank.dll");
if ( (handleVBank is null) || (handleSberbank is null) )
{
writeln("Couldn't find necessary DLL files");
return 1;
}
getBankInstance get1 = cast(getBankInstance)
GetProcAddress(handleVBank, "Get".toStringz);
getBankInstance get2 = cast(getBankInstance)
GetProcAddress(handleSberbank, "Get".toStringz);
if ( get1 is null || get2 is null )
{
writeln("Couldn't load factory functions");
return 2;
}
getBankInstance get;
IBank vbank = (*get1)();
IBank sberbank = get2();
uint sbnum = 100500;
uint vbnum = 128500;
writeln("You have an account in Sberbank (100500)");
auto balance = sberbank.getBalance(sbnum);
writefln("getBalance(%d) = %s", sbnum, balance);
bool res = sberbank.withdraw(sbnum, 500.0);
writefln("withdraw(%d, %f) = %s", sbnum, 500.0, res);
writeln("You got it!");
...
-----------------
The output I get is (in case I use extern (Windows, C or Pascal)):
-----------------
You have an account in Sberbank (100500)
getBalance(100500) = -nan
got into GenericBank::getBalance() // this is an output from a method
called inside the DLL
account number = 100500 // inside the DLL
balance is 1100 // inside the DLL
withdraw(100500, 500.000000) = false
You got it!
-----------------
First, to interact with C++ `interface` you need:
---
extern(C++) interface Ixxx
{
...
}
---
Your `IBank` C++ functions are declared as `APIENTRY` which is almost
definitely defined as `__stdcall`. So the correct interface declaration is:
---
extern(C++) interface IBank
{
extern(Windows) const char* getLastError();
...
}
---
As all your functions are `APIENTRY`, write `extern(Windows):` before
them. And use `c_ulong` as analogue of `unsigned long`. So full correct
`IBank` interface declaration here:
---
import core.stdc.config: c_ulong;
extern(C++) interface IBank
{
extern(Windows):
const char* getLastError();
const char* getDetail(char* detail);
bool deposit(c_ulong number, double amount);
bool withdraw(c_ulong number, double amount);
double getBalance(c_ulong number);
bool transfer(c_ulong numberFrom, IBank* bankTo, c_ulong numberTo,
double amount);
bool transferAccept(IBank* bankFrom, c_ulong numberTo, double amount);
};
---
--
Денис В. Шеломовский
Denis V. Shelomovskij
