Vala binding: how to pass args to free_function?

Platform Language bindings
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1

Hi guys,

Met a big stone on the way: how to pass args to free_function

[CCode (cname = "SQLFreeHandle")]
public Return free_handle(HandleType handle_type, void* handle);

[CCode (cname = "void", free_function = "SQLFreeHandle", has_type_id = false)]
[Compact]
public class Statement {
}

Anybody could give me a hand? Thanks in advanced.

2

As far as I know this is not possible. I would create your own free function without parameters in the vapi, that calls free_handle with the right handle.

3 
[CCode (cname = "SQLFreeHandle")]
public Return free_handle(HandleType handle_type, void* handle);

public void free_stmt(void* handle)
{
    free_handle(HandleType.STMT, handle);
}

[CCode (cname = "void", free_function = "free_stmt", has_type_id = false)]
[Compact]
public class Statement {
}

I’ve tried this solution, then ld command failed: undefined reference to `free_stmt’

4

I would add a [CCode (cname = "mylib_free_stmt to the free_stmt function. Then you can use “mylib_free_stmt” in free_function = ...

5

Maybe mark with attribute CCode with the final function is the rightt way to solve this problem.

6

I’v tried your solution, compile failed.

7

What was the compilation error and can you show the source code you used now?

8

The ODBC vapi source： odbc.vapi ( simplified model)

[CCode (cheader_filename = "windows.h,sqlext.h")]
namespace Odbc {
    [CCode (cname = "ODBCVER")]
    public const int VERSION;

    [CCode (cname = "SQLHANDLE", has_type_id = false)]
    public struct Handle : long {}

    [CCode (cname = "SQLHWND", has_type_id = false)]
    public struct Hwnd : long {}

    [CCode (cname = "SQLPOINTER", has_type_id = false)]
    public struct Pointer : long {}

    // Global function -------------------------------------------------------
    [CCode (cname = "SQLAllocHandle")]
    public Return alloc_env(HandleType handle_type, void* input_handle, out Environment output_handle);

    [CCode (cname = "SQLAllocHandle")]
    public Return alloc_dbc(HandleType handle_type, void* input_handle, out Connection output_handle);

    [CCode (cname = "SQLAllocHandle")]
    public Return alloc_stmt(HandleType handle_type, void* input_handle, out Statement output_handle);

    [Version (since = "3.8")]
    [CCode (cname = "SQLCancelHandle")]
    public Return cancel_handle(HandleType handle_type, void* handle);

    [CCode (cname = "SQLFreeHandle")]
    public Return free_handle(HandleType handle_type, void* handle);
    
    [CCode (cname = "void", free_function = "SQLFreeEnv", has_type_id = false)]
    [Compact]
    public class Environment {
        public static Environment @new()
        {
            Environment env;
            var retval = alloc_env(HandleType.ENV, null, out env);
            GLib.assert(succeeded(retval));

            return env;
        }
    }
    
    [CCode (cname = "void", free_function = "SQLFreeConnect", has_type_id = false)]
    [Compact]
    public class Connection {
        public static Connection @new(Environment env)
        {
            Connection connection;
            var retval = alloc_dbc(HandleType.DBC, env, out connection);
            GLib.assert(succeeded(retval));

            return connection;
        }
    }
    
    public void free_stmt(void* handle)
    {
        free_handle(HandleType.STMT, handle);
    }
    
    [CCode (cname = "void", free_function = "odbc_free_stmt", has_type_id = false)]
    [Compact]
    public class Statement {
        public static Statement @new(Connection connection)
        {
            Statement statement;
            var retval = alloc_stmt(HandleType.STMT, connection, out statement);
            GLib.assert(succeeded(retval));

            return statement;
        }
    }
}

Test function source code: odbc_vapi.vala( simplified model)

public void odbc_connection_test_alloc_statement()
{
    Odbc.Environment env = Odbc.Environment.new();

    Odbc.Return retval = env.set_attribute(Odbc.Attribute.ODBC_VERSION, (void *)Odbc.OdbcVersion.ODBC3, Odbc.ValueType.INTEGER);
    GLib.assert(Odbc.succeeded(retval));

    Odbc.Connection connection = Odbc.Connection.new(env);
    retval = connection.connect("Northwind".data, null, null);
    GLib.assert(Odbc.succeeded(retval));

    Odbc.Statement stmt;
    retval = connection.alloc_stmt(out stmt);
    GLib.assert(Odbc.succeeded(retval));

    retval = connection.disconnect();
    GLib.assert(Odbc.succeeded(retval));
}

the output message:

"cc" @Illuminate/libilluminate.dll.rsp
C:/msys/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: Illuminate/libilluminate.dll.p/meson-generated_Supports_Providers_Odbc_provider_odbc.c.obj: in function `odbc_statement_new':
D:\Codelabs\GitHub\kangaroo\build/../vapi/odbc.vapi:738: undefined reference to `odbc_free_stmt'
C:/msys/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.2.0/../../../../x86_64-w64-mingw32/bin/ld.exe: Illuminate/libilluminate.dll.p/meson-generated_Supports_Providers_Odbc_provider_odbc.c.obj: in function `kangaroo_illuminate_supports_providers_odbc_provider_test':
D:\Codelabs\GitHub\kangaroo\build/../Illuminate/Supports/Providers/Odbc/provider_odbc.vala:11: undefined reference to `odbc_free_stmt'
collect2.exe: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.

Use free_stmt to generate the code body: free_stmt((void*)0); 

[CCode (cname = "void", free_function = "odbc_free_stmt", has_type_id = false)]
[Compact]
public class Statement {
    public static Statement @new(Connection connection)
    {
        Statement statement;
        var retval = alloc_stmt(HandleType.STMT, connection, out statement);
        GLib.assert(succeeded(retval));
        free_stmt((void*)0);

        return statement;
    }
}

The output message:

odbc_vapi.c:1101:1: error: static declaration of 'odbc_free_stmt' follows non-static declaration
tests/kangaroo.exe.p/odbc_vapi.c:41:63: note: previous implicit declaration of 'odbc_free_stmt' with type 'void(void *)'
   41 | VALA_EXTERN void odbc_environment_test_datasources (void);
      |                                                               ^         
tests/kangaroo.exe.p/odbc_vapi.c:41:63: note: in definition of macro '_odbc_free_stmt0'
   41 | VALA_EXTERN void odbc_environment_test_datasources (void);
      |                                                               ^         
[5/12] Linking target Illuminate/libilluminate.dll
ninja: build stopped: subcommand failed.
9

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