Re: [Vala] A few newbie's questions

[Giulio Paci <giuliopaci gmail com>]

Hi!
Il 04/02/2011 01:16, Sandino Flores Moreno ha scritto:
> To use PACKAGE and VERSION  declare them as extern in your vala source code.
>    
  You are a life saver! :-) I was not aware of the "extern" keyword in 
Vala.
> Sorry, I pasted the man page of gets but FileStream.gets is the
> wrapper of fgets.
>
> char *fgets(char *s, int size, FILE *stream);
>         fgets() reads in at most one less than size characters from stream  and
>         stores  them  into  the buffer pointed to by s.  Reading stops after an
>         EOF or a newline.  If a newline is read, it is stored into the  buffer.
>         A '\0' is stored after the last character in the buffer.
>    
This was not a problem (I read the fgets section of the manual). What 
was misleading was the lack of information in 
http://www.valadoc.org/glib-2.0/GLib.FileStream.html: when I decided to 
try FileStream.read_line() and to avoid FileStream.gets(), I decided so 
because I read the gets() manual, thinking that FileStream.gets() 
translates to gets().
> That means that FileStream.gets will stop reading when the buffer size
> is reached.
> However, fgets does not know of utf-8.
>
> You will have instead to look at the objects in GIO (the glib
> input/output objects/functions).
>    
Sooner or later I will try the GIO, but at this time I prefer not to use it.
Do you think it is ok to concatenate two strings resulting from fgets 
with an incomplete utf8 character at the end? I tried it and everything 
is working, but I'm not sure what is the meaning, in vala string, of a 
partial utf8 character.

Bests,
    Giulio.
> On Thu, Feb 3, 2011 at 5:33 PM, Giulio Paci<giuliopaci gmail com>  wrote:
>    
> > Hi Sandino,
> >
> >     thank you for your very quick reply,
> >
> >
> > Il 03/02/2011 23:23, Sandino Flores Moreno ha scritto:
> >
> >      
> > > On Thu, Feb 3, 2011 at 3:27 PM, Giulio Paci<giuliopaci gmail com>  wrote:
> > >        
> > > > 1) I tried to create a gstreamer plugin following the Gstreamer Plugin
> > > > Writer's Guide
> > > > (http://gstreamer.freedesktop.org/data/doc/gstreamer/head/pwg/html/index.html).
> > > > I was able to create the plugin, but I was not able to create it using
> > > > vala alone, because I was not able to insert in the generated C output
> > > > this code:
> > > >
> > > > #include<glib.h>
> > > > #include<gst/gst.h>
> > > > GST_PLUGIN_DEFINE (
> > > >      GST_VERSION_MAJOR,
> > > >       GST_VERSION_MINOR,
> > > >       "my_filter",
> > > >       "My filter plugin",
> > > >       plugin_init,
> > > >       VERSION,
> > > >       "LGPL",
> > > >       "GStreamer",
> > > >       "http://gstreamer.net/";
> > > >       )
> > > >
> > > > At last I decided it was not a big issue to put this code in a C file,
> > > > but is there any way to directly inject C code in vala?
> > > >          
> > > Regarding question 1:
> > > ==================
> > >
> > > Check the next source code:
> > > https://github.com/tigrux/gst-plugin-omap4videodecbin/blob/master/gst/gstomap4videodecbin.vala
> > >
> > > There you can see a line like these:
> > > public const Gst.PluginDesc gst_plugin_desc = {
> > > ...
> > > }
> > >
> > > That's what you are missing in your gstreamer plugin.
> > >
> > >        
> > This is very close to what I wanted.
> > What I'm still missing is the possibility to use PACKAGE and VERSION
> > macros.
> >      
> > > > 2) I tried to read a file, one line at time, using the FileStream
> > > > object, but I was not able to get the desired result with the current
> > > > API, because I needed the whole line (EOL inclusive), while read_line()
> > > > removes it. The work around of adding a new line to each line does not
> > > > allow to know if the last character of the file was a new line or not.
> > > > Is there any way to (easily) read a file including the EOL character?
> > > >          
> > > Regarding question 2:
> > > ==================
> > >
> > > Use the method FileStream.gets which corresponds to fgets.
> > > public unowned string FileStream.gets (char[] s);
> > >
> > > > From the man page of fgets:
> > >         gets() reads a line from stdin into the buffer pointed to  by  s  until
> > >         either  a  terminating newline or EOF, which it replaces with '\0'.  No
> > >         check for buffer overrun is performed (see BUGS below).
> > >
> > >         gets() reads a line from stdin into the buffer pointed to  by  s  until
> > >         either  a  terminating newline or EOF, which it replaces with '\0'.  No
> > >         check for buffer overrun is performed (see BUGS below).
> > >
> > >        
> > This sounds exactly what I need. As I need to have valid utf-8
> > characters, do I have to perform any check for the last returned bytes
> > (if the line is longer than the char array) or does FileStream.gets
> > guarantee that the last returned character is valid?
> >
> > By the way, Is there a better documentation than
> > http://www.valadoc.org/glib-2.0/GLib.FileStream.html? By reading it I
> > avoided even trying FileStream.gets as I thought it was just some sort
> > of gets and not fgets.
> >
> > Bests,
> >     Giulio.
> >
> >
> >      
>