Re: [Dbmail-dev] dynamic library loading

[Dan Weber]

Aaron Stone wrote:

If the code is changed to authdb->this()  and msgdb->that(), then using two
different databases is *not* any more complicated *at all*. Just check the
config file, and either open up two libraries or open one and copy the struct.

I'm not enthused by the wrapper functions, can't we just import the symbol
db_whatever directly? Granted that means that you'd have to call the libtool
dl functions one at a time, it's uglier, imho, to have these wrappers.

To immeaditely simplify this, I used the magic of the preprocessor. See attachment.

Dan Weber

Aaron


Paul J Stevens <[EMAIL PROTECTED]> said:

Allowing people to use different sql backends for auth and storage was my idea iirc. It was more a logical conclusion following from clean separation of both code bases - implied by the auth-ldap code, rather than a serious feature request.

Dan Weber wrote:

On Sat, May 29, 2004 at 08:33:10AM -0000, Aaron Stone wrote:

This is probably the cleanest way to do it. Renaming all of the function
calls to reference struct members shouldn't be too hard. I believe that
you could instead load in the symbols for each function one at a time,
but then it's not clear that you're working with an external symbol
within the code. Since some people also suggested being able to use a
different sql database for auth a storage, the struct would make it much
easier to separate them.

Having people use a different sql database for auth, adds a lot of
complexity.  I personally don't think it is a good idea.  So for
making compatibility functions, something like this.

int db_check_connection(void)
   foo->db_check_connect(void);

Don't forget to define a versioning scheme. The library should export a
dbmail_api_version symbol with some kind of major.minor.micro scheme or
rev.compat scheme so that before you import the structure with all of the
functions you know that it will be the size and signature you're expecting.

Good call, that way we can create compatibility versioning scheme.

Dan Weber


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  Paul Stevens                                  mailto:[EMAIL PROTECTED]
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#if !defined(DBCOMPAT_H) && !defined(NO_DBCOMPAT_MACROS)
#define DBCOMPAT_H
#include "dbmailtypes.h"
#include "dbapi.h"
#include "dbmail.h"

extern struct db_api *dbcalls;
#define TO_CHAR (dbcalls->TO_CHAR)
#define TO_DATE (dbcalls->TO_DATE)

#define db_check_connection() (dbcalls->db_check_connection())
#define db_connect() (dbcalls->db_connect())
#define db_num_rows() (dbcalls->db_num_rows())
#define db_num_fields() (dbcalls->db_num_fields())
#define db_free_result() (dbcalls->db_free_result())
#define db_get_result(r,f) (dbcalls->db_get_result(r,f))
#define db_disconnect() (dbcalls->db_disconnect())
#define db_insert_result(x) (dbcalls->db_insert_result(x))
#define db_query(q) (dbcalls->db_query(q))
#define db_escape_string(to,from,len) (dbcalls->db_escape_string(to,from,len))
#define db_do_cleanup(tables,num) (dbcalls->db_do_cleanup(tables,num))
#define db_get_length(r,f) (dbcalls->db_get_length(r,f))
#define db_get_affected_rows() (dbcalls->db_get_affected_rows())
#define db_use_msgbuf_result() (dbcalls->db_use_msgbuf_result())
#define db_store_msgbuf_result() (dbcalls->db_store_msgbuf_result())
#define db_get_result_set() (dbcalls->db_get_result_set())
#define db_set_result_set(set) (dbcalls->db_set_result_set(set))

#endif

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