Re: [Vala] Unnecessary g_strdup and compile error.

[Aleksander Wabik <alex wabik gmail com>]

Hi,

please see a comment inline,

> Hello,
> (sorry, my English is not so good ;)
>
> I often write the following codes.
> ----------------------------------------------------------------
> void main () {
>    var home = Environment.get_home_dir ();
>    print ("%s\n", home);
> }
> ----------------------------------------------------------------
>
> Then, unnecessary g_strdup is generated. 
> ----------------------------------------------------------------
> void _vala_main (void) {
>    const gchar* _tmp0_ = NULL;
>    gchar* _tmp1_;
>    gchar* home;
>    _tmp0_ = g_get_home_dir ();
>    _tmp1_ = g_strdup (_tmp0_);
>    home = _tmp1_;
>    g_print ("%s\n", home);
>    _g_free0 (home);
> }
> ----------------------------------------------------------------
>
> It is necessary to write a tedious following codes to avoid it. 
> ----------------------------------------------------------------
> void main () {
>    unowned string home = Environment.get_home_dir ();
>    print ("%s\n", home);
> }
> ----------------------------------------------------------------

If get_home_dir() returns unowned string, and you make assignment to
owned string reference, you get a copy of this string. Each owned
reference of a string will delete the string when it goes out of scope,
that's why this strdup is needed (note: most objects don't behave that
way). Please see that the value returned by g_get_home_dir(), _tmp0_,
is not freed in the C code.

best regards,

> Is not unnecessary g_strdup generated without writing a tedious code?
>
> After that, if the following codes are written, it becomes a compile error. (Vala 0.11.2)
> ----------------------------------------------------------------
> void main () {
>    const string home = Environment.get_home_dir ();
>    print ("%s\n", home);
> }
> ----------------------------------------------------------------
>
> /home/kentaro/work/VALA/unnecessary_strdup.vala.c: In function '_vala_main':
> /home/kentaro/work/VALA/unnecessary_strdup.vala.c:18: error: invalid initializer
> error: cc exited with status 256
> Compilation failed: 1 error(s), 0 warning(s)
>
> Best regards,
>
> -- 
> Kentaro NAKAZAWA (from Japan)
> _______________________________________________
> vala-list mailing list
> vala-list gnome org
> http://mail.gnome.org/mailman/listinfo/vala-list


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