From: John Mastro <john.b.mastro@gmail.com>
To: Emacs <help-gnu-emacs@gnu.org>
Cc: Christopher Wellons <wellons@nullprogram.com>
Subject: Re: emacsql-mysql - best way to close connection?
Date: Sat, 1 Apr 2017 12:52:10 -0700 [thread overview]
Message-ID: <CAOj2CQR-4Qn-w67MuBXq_9UPge7YVh4_0fiCHT24_jj3V_ogzg@mail.gmail.com> (raw)
In-Reply-To: <CAEySM9F2GFsyVOYDQLeiuNeuuq3qZN6RL-Zc4Zk7bX0=n3L-7w@mail.gmail.com>
Guido Van Hoecke <guivho@gmail.com> wrote:
>> I create a mysql connection in a let* form:
>>
>> (let* ((host "mysql.host.com")
>> (dummy (netrc-credentials host)) ;; needed to define remaining netrc stuff
>> (info (netrc-machine (netrc-parse (expand-file-name "~/.netrc")) host))
>> (id (cdr (assoc "login" info)))
>> (pw (cdr (assoc "password" info)))
>> (db (emacsql-mysql "database" :user id :password pw :host host)))
>> ....)
>>
> I added (delete-process "emacsql-mysql") as last elisp form of the let*
> form. This does kill the process. Still I wonder if this is the way to go?
It looks like there's a function `emacsql-close' for that.
If your code that uses the connection may raise an error (which would
cause evaluation to never reach the call to `emacsql-close' or similar),
then you may want to wrap it in `unwind-protect':
(let* (...
(db (emacsql-mysql "database" :user id :password pw :host host)))
(unwind-protect
(progn ...)
(emacsql-close db)))
Where you code that uses the connection would go inside the `progn'.
There's also a macro `emacsql-with-connection' that encapsulates this
pattern: create a connection, evaluate some forms, then ensure
`emacsql-close' is called even in the event of an error.
John
next prev parent reply other threads:[~2017-04-01 19:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-01 7:14 emacsql-mysql - best way to close connection? Guido Van Hoecke
2017-04-01 9:54 ` Guido Van Hoecke
2017-04-01 19:52 ` John Mastro [this message]
2017-04-02 11:31 ` Guido Van Hoecke
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