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From:Warren Young Date:July 13 2007 3:20am
Subject:Connection::connect() interface is changing
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I have started work on MySQL++ v3.0.

My task at the moment is cleaning up the connection establishment 
interface.  I have something I like, but I thought I'd run it past the 
list just in case.

The first thing is that we're dropping the parameters for turning on 
compression and setting the connection timeout.  You can set those 
through Connection::set_option() instead.

The parameters for the communication channel are a mess.  In v2 there 
are three of them, you can't use all of them at once, and together they 
select among at least four different types of IPC.  (See the 
mysql_real_connect() docs if you disbelieve!)  I've pushed this 
complexity out of the interface and into the implementation of 
Connection; there's now just one string parameter for all of this, with 
a bit of clever parsing within the class to figure out what you mean.

None of that should cause problems.

I am less sanguine about the next one, however.  I want to reorder the 
parameters to be in order of likelihood of use.  I wouldn't have any 
qualms about doing this if it would cause compilation problems, but the 
compiler won't see any difference: all I'm doing is swapping two const 
char* parameters.  I figure it'll be common for people to fail to notice 
the interface difference until they try to find out why their program 
stopped working when rebuilding it for v3.

The final interface looks like this:

     Connection(cchar* db, cchar* passwd = 0, cchar* user = 0,
             cchar* server = 0, unsigned long client_flag = 0);

db is first because 99% of uses will need to specify a database.  The 
only use I can think of where you don't specify a database up front is 
when creating databases programmatically, and that happens only once 
during setup in a typical system.

The next parameter used to be host, but I figure the default works in 
the majority of cases.  Far more likely is the need to give a password. 
  A controversial aspect of this change is that the default value for 
password used to be "", and is now 0 (NULL).  The C API makes no 
distinction between these values, for most parameters.  But for 
password, the former means an empty password, and the latter means the C 
API library is supposed to go and read the value from a defaults file. 
I figure having a defaults file is more likely than having a blank 
password in this security-conscious era.

The user parameter hasn't changed, except for "" becoming 0, which is 
just for stylistic consistency.

Then there's server, which stands in for the old host, port and 
socket_name arguments.  I figure this is less likely to be specified 
than user.  I know in my programs, I almost always use different user 
names in my database than my login name, since database user names are 
more about data access roles than overall data ownership.  And, I almost 
always just take the default on server address; it's running on the same 
machine as the client program in most cases.

Everything else remains the same.

I'm also changing the examples' command line interfaces to match.

Complaints, comments, kudos?
Thread
Connection::connect() interface is changingWarren Young13 Jul
  • Re: Connection::connect() interface is changingDrew M.13 Jul
    • Re: Connection::connect() interface is changingWarren Young13 Jul
  • RE: Connection::connect() interface is changingYuantu.Huang13 Jul
    • Re: Connection::connect() interface is changingWarren Young13 Jul
      • RE: Connection::connect() interface is changingJoel Fielder13 Jul
        • RE: Connection::connect() interface is changingWilliam F. Dowling13 Jul
        • Re: Connection::connect() interface is changingWarren Young14 Jul
          • Re: Connection::connect() interface is changingWarren Young14 Jul
            • Re: Connection::connect() interface is changingAlex Burton15 Jul
              • Re: Connection::connect() interface is changingPeter Garner15 Jul
              • Re: Connection::connect() interface is changingWarren Young16 Jul
          • RE: Connection::connect() interface is changingJoel Fielder16 Jul
            • Re: Connection::connect() interface is changingWarren Young16 Jul
              • Re: Connection::connect() interface is changingAxel Howind16 Jul
                • Re: Connection::connect() interface is changingWarren Young16 Jul
  • Re: Connection::connect() interface is changingAxel Howind13 Jul
    • Re: Connection::connect() interface is changingWarren Young14 Jul
      • Re: Connection::connect() interface is changingAxel Howind16 Jul
  • Re: Connection::connect() interface is changingAlex Burton13 Jul
    • Re: Connection::connect() interface is changingWarren Young14 Jul
  • RE: Connection::connect() interface is changingJim Wallace13 Jul
    • Re: Connection::connect() interface is changingWarren Young14 Jul