PureBasic Forums - English

I just purchased PureBasic this past weekend so I’m still new to the language. I’m trying to use PureBasic to interface with other programs. I was using the very cool Interface Generator tool, but I’m having some problems.

Here’s an example of the C++ function I’m trying to access:

[VOffset($24)] HRESULT LogMessage([in] BSTR in_Message,
[in, optional, defaultvalue=8] siSeverity in_Severity)

The interface generator creates code that looks like this:

Interface Application Extends IDispatch
LogMessage(a,b)
EndInterface


I did some searches on the forums and I found some info about converting strings to BSTR, but nothing that works so far. If I try and pass it a string I get an error: “Bad parameter type, number expected instead of string” so I think I need to pass it a pointer, but I’m not sure.

Does anyone know how I can convert a string into a BSTR (a Unicode string?) and get the pointer?

did you try the prototype with 'p-bstr' type of purebasic 4 ?
something like that:

p-bstr is a pointer to a bstr.
Correct if I am not wrong.

Flype is right, using this pseudo-type will automatically convert PB string in a BSTR one, so it should work.

Thank you! Prototypes look like the way to go

I was reading about prototypes in the readme file and it's still not clear to me how to use it with a DLL. Could I do something like this? not that this works, I really don't understand how this should come together just yet.
also, can I use 'Interface' like I was before to access COM objects? If so how do I prototype the COM object? I guess I would still need to lookup the required types for the parameters.
sample interface:

kyleh wrote:

Code: Select all

OpenLibrary(0, "core.dll")
Prototype.l LogMessage(InMessage.p-bstr,DefaultValue=8)
LogMessage ( "test...",8 )

About the prototype, it just define a new type (like a structure, interface etc.). So you have to affect this type to a variable, and use GetFunction() to get the address of the real function:

When I use this I'm getting an Assembler Error.
PureBasic.asm [68]:
CALL _SYS_ToUnicode@4
error: undefined symbol

I'm sure I'm still missing something, but I can't find any information on this error.

Code: Select all

Prototype.l LogMessagePrototype(InMessage.p-bstr,DefaultValue=8)

OpenLibrary(0, "core.dll")

LogMessage.LogMessagePrototype = GetFunction(0, "LogMessage")
if LogMessage ; is the function really found ?
  LogMessage ( "test...")
endif 

[/code]

You found a bug, it will be fixed for the next beta, thanks !

Thanks for all your help! I'm looking forward to the next update

So, it turns out I really need to get a program done for work soon and I would like to use Purebasic. Since I don't know when the next beta is going to be released is there an easy way to do the same thing without Prototype?

Sure, you just have to use 'MultiByteToWideChar' to convert your string in unicode (not needed if you compile with 'unicode' mode) and then call SysAllocString() to create a BSTR string. (and then SysFreeString() to free it).