Re: Why cani i initialize "prefix" with a default string?

[Gary Kline <kline thought org>]

On Sat, Dec 10, 2011 at 03:23:10AM +0100, David Ne??as wrote:
> Date: Sat, 10 Dec 2011 03:23:10 +0100
> From: David Ne??as <yeti physics muni cz>
> Subject: Re: Why cani i initialize "prefix" with a default string?
> To: Gary Kline <kline thought org>
> Cc: GTK Devel List <gtk-app-devel-list gnome org>
>
> On Fri, Dec 09, 2011 at 05:40:09PM -0800, Gary Kline wrote:
> >     guys, i am appending a piece of gtk test code.  it saves the
> >     internal filename buffer for "espeak -f %s ifbuf" to run
> >     on--to be the user's voice.  if i set 
> >
> >     static char *prefix = "talk"; 
> >
> >     then back up and enter another string in the box at the
> >     bottom, strange things happen.  Anybody know where i am
> >     messing up?
>
> Strange things most likely occur after attempting to free the const
> string in entry_changed_cb()
>
>     g_free(prefix);
>
> which was fine if prefix was NULL initially.  You can use -Wwrite-strings
> to catch that.  

        your advice was right on target.  i changed the gcc line,
        then checked 

        if (prefix == NULL)
                printf("NOT NULL\n")

        early in main().  since i set prefix , the string printed to
        stdout.  long-story-short, my test program works the way i 
        want.

> Unforutnately, passing constant strings as various
> user-data-kind arguments or to g_hash_table_insets() then produces
> warnings too.

        okay; i'll watch out!

> Also learn to use valgrind; it would show you this problem immediately.

        a couple hours ago i installed valgrind and a front end.

        The next thing on my to-try list is to get the
        increase/decrease buttons together;  this means reading up
        on the hbox stuff.  i found one example somewhere last week
        and it looks tricky.  --anyhow, thans for your keen
        insights.  

        gary


> Yeti

-- 
 Gary Kline  kline thought org  http://www.thought.org  Public Service Unix
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