Trying to understand Destructors

rtcary

I have a class that is created when the page opens. It contains the code to open a database and a table(s) as well as methods to query the table(s). There is a destructor in the class, but it does not appear to be called I have put a print statement in the destructor).

Could it be that using a print statement is not the way to see if the destructor is being called?

Many thanks....

Todd

rtcary

Yes, a print statement is not the way to verify that the destructor is being called; I wrote to a file and it is being called. Now I have a question that created this thread:

I use the destructor to close the database: open once and close once. So far, so good. However, if I introduce an error (e.g. give the query a name of a table that does not exist), the connection object when used in the close (e.g. mysql_close($connection) throws an error.

How can I code around this?

Thank you...

Todd

NogDog

I have no idea why an invalid query should invalidate your connection object, other than if the connection and the query are in some way too closely coupled in your class/object design. (I know that's very vague, but without any code, that's all I've got. 🙂 )

jgetner

can you supply a preview of the code? there could be various options on the reason your code is not working. but by your previous thread i'am so confused.... so you get error when you try access a table that does not exist?. well i would hope you get some kind of error for that.

rtcary

Programmer error! My apologies!

A technique I have used for some time is to daisy chain the opening of the table classes so the DB is opened only one time. Each major table has it's own class that contains the special queries and they are opened like this:

$ses = new sessions($link, $gvars[host], $gvars[user], $gvars[password], $gvars[database]);
$link = $ses->link;
$fam = new families($link, $gvars[host], $gvars[user], $gvars[password], $gvars[database]);
$peo = new people($link, $gvars[host], $gvars[user], $gvars[password], $gvars[database]);

The $link for the first table class is null, so the first class creates the $link (DB connection). In cloning the classes for a new project, I left out the statement that checks to see if the class created the $link: if it did, then it will close the DB else ignore the mysql_close().

The table classes, other than the first, were trying to close the DB that had already been closed!!