ExternalStructure with pointer to functions

[Dima Smirnov]

Hello! How can I describe a similar structure:

typedef struct _ISciterAPI {
UINT version; // is zero for now

LPCWSTR SCFN( SciterClassName )();
UINT SCFN( SciterVersion )(BOOL major);
} ISciterAPI;

in Dolphin?

[Udo Schneider]

Can't give you code - but I did this a few years back.

Create an external library and add an method with a call signature
matching the function you got below.

Then you need to get the ExternalMethod instance (e.g. UserLibrary
methodDictionary at: #blockInput:). This ExternalMethod instance
contains and ExternalDescriptor which contains the (for DLLs resolved)
proc address (check for #procAddress). You need to write the address you
got below into the descriptor literal. Then you can call the function
you got below by using an instance of your own lib. I /think/ there was
also some lazy/caching stuff going on. You might have to check.

Can't give you the exact code. But this is the rough outline.

CU,

Udo

[Dima Smirnov]

Thank you, Udo, for your answer.
I got the following code, I don’t know how correct it is,but it works :)

ExternalStructure subclass: #SCITERAPI
SCITERAPI class >> defineFields
self
defineField: #version type: WORDField new; "UINT version; // is zero for now"
defineField: #SciterClassName type: INT_PTRField new ;
defineField: #SciterVersion type: INT_PTRField new …


ExternalLibrary subclass: #SciterLibrary
instanceVariableNames: 'api'
SciterLibrary >> api
api := self SciterAPI.
^api

SciterLibrary >>SciterAPI
"Private - SciterAPI_ptr sciterAPI = (SciterAPI_ptr) GetProcAddress(hm, SciterAPI);"

<stdcall: SCITERAPI* SciterAPI>
^self invalidCall

SciterLibrary >> SciterClassName
| val |
val := self
runSciterMethod: 's <stdcall: byte* _ >'
address: api SciterClassName
arguments: #().
^Utf16String fromAddress: val

SciterLibrary >> runSciterMethod: aSource address: anAddress arguments: anArgs
| method val |
method := Compiler compile: aSource in: Object.
method descriptorLiteral dwordAtOffset: 0 put: anAddress.
val := method value: self withArguments: anArgs.
^val

And an example of use:
sc:= SciterLibrary default.
sc api.
sc SciterClassName. -> 'H-SMILE-CHILD'