[sqlite] question on sqlite3 api
I am creating a Delphi wrapper for sqlite 3 API. I am having some trouble interpeting the documentation and c header files. specifically, I am not sure how to handle these: int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*)); int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*)); with regard to the last parameter. I am reading it as being a pointer to a function that takes a pointer and returns nothing (a procedure). but, nowwhere is it mentioned what this function is supposed to do... also, the documentation in sqlite3.h mentions a parameter eCopy, which defines whether bound parameters are static or volatile. but, I cannot see where this is declared and/or passed. I am guessing that this has to do with this last weird parameter. Could somebody, preferably DRH, step in and explain, please ?
Re: [sqlite] question on sqlite3 api
CARIOTOGLOU MIKE wrote: I am creating a Delphi wrapper for sqlite 3 API. I am having some trouble interpeting the documentation and c header files. specifically, I am not sure how to handle these: int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*)); int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*)); with regard to the last parameter. I am reading it as being a pointer to a function that takes a pointer and returns nothing (a procedure). but, nowwhere is it mentioned what this function is supposed to do... also, the documentation in sqlite3.h mentions a parameter eCopy, which defines whether bound parameters are static or volatile. but, I cannot see where this is declared and/or passed. I am guessing that this has to do with this last weird parameter. Could somebody, preferably DRH, step in and explain, please ? I asked the same queston, check out: http://article.gmane.org/gmane.comp.db.sqlite.general/6453 -Andy
Re: [sqlite] question on sqlite3 api
CARIOTOGLOU MIKE wrote: I am creating a Delphi wrapper for sqlite 3 API. I am having some trouble interpeting the documentation and c header files. specifically, I am not sure how to handle these: int sqlite3_bind_blob(sqlite3_stmt*, int, const void*, int n, void(*)(void*)); int sqlite3_bind_text(sqlite3_stmt*, int, const char*, int n, void(*)(void*)); with regard to the last parameter. I am reading it as being a pointer to a function that takes a pointer and returns nothing (a procedure). but, nowwhere is it mentioned what this function is supposed to do... also, the documentation in sqlite3.h mentions a parameter eCopy, which defines whether bound parameters are static or volatile. but, I cannot see where this is declared and/or passed. I am guessing that this has to do with this last weird parameter. Could somebody, preferably DRH, step in and explain, please ? Another documentation bug The void(*)(void*) is indeed a pointer to a procedure that takes a single void* argument. This is a pointer to a destructor for the text or blob you pass in. SQLite will invoke the destrutor on the text or blob passed in when SQLite has finished using it. There are two special values for this destructor argument: SQLITE_STATIC and SQLITE_TRANSIENT. If the destructor is set to SQLITE_STATIC, then SQLite assumes that the string or blob being passed in is permanently and statically allocated and does not need to be destroyed, ever. If the argument is SQLITE_TRANSIENT, then SQLite immediately makes its own private copy of the string or blob before it returns and no destructor is ever called on the original. Example: If you have a string held in memory obtained from malloc(), you can pass that string to sqlite3_bind_text() and give it a pointer to free() as the destructor. Then SQLite will free() the string when it has finished using it. -- D. Richard Hipp -- [EMAIL PROTECTED] -- 704.948.4565
