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<refentry id="glib-changes" revision="17 Jan 2002">

<refmeta>

<refentrytitle>Changes to GLib</refentrytitle>

<manvolnum>3</manvolnum>

<refmiscinfo>Changes to GLib</refmiscinfo>

</refmeta>

<refnamediv>

<refname>Changes to GLib</refname>

<refpurpose>

Incompatible changes made between successing versions of GLib

</refpurpose>

</refnamediv>

<refsect1>

<title>Incompatible changes from 2.0 to 2.2</title>

<itemizedlist>

<listitem>

<para>

GLib changed the seeding algorithm for the pseudo-random number

generator Mersenne Twister, as used by <structname>GRand</structname>

and <structname>GRandom</structname>. This was necessary, because some

seeds would yield very bad pseudo-random streams. Also the

pseudo-random integers generated by

<function>g_rand*_int_range()</function> will have a

slightly better equal distribution with the new version of GLib.

</para>

<para>

Further information can be found at the website of the Mersenne

Twister random number generator at 

url="http://www.math.keio.ac.jp/~matumoto/emt.html">http://www.math.keio.ac.jp/~matumoto/emt.html</ulink>.

</para> 

<para>

The original seeding and generation algorithms, as found in GLib

2.0.x, can be used instead of the new ones by setting the environment

variable <envar>G_RANDOM_VERSION</envar> to the value of '2.0'. Use

the GLib-2.0 algorithms only if you have sequences of numbers generated

with Glib-2.0 that you need to reproduce exactly.  

</para> 

</listitem>

</itemizedlist>

</refsect1>

<refsect1>

<title>Incompatible changes from 1.2 to 2.0</title>

<itemizedlist>

<listitem>

<para>

The event loop functionality <structname>GMain</structname> has extensively 

been revised to support multiple separate main loops in separate threads. 

All sources (timeouts, idle functions, etc.) are associated with a 

<structname>GMainContext</structname>.

</para>

<para>

Compatibility functions exist so that most application code dealing with

the main loop will continue to work. However, code that creates new custom 

types of sources will require modification.

</para>

<para>

The main changes here are:

  <itemizedlist>

  <listitem>

  <para>

   Sources are now exposed as <type>GSource *</type>, rather than simply as 

   numeric ids.

  </para>

  </listitem>

  <listitem>

  <para>

   New types of sources are created by structure "derivation" from 

   <structname>GSource</structname>, so the <literal>source_data</literal> 

   parameter to the <structname>GSource</structname> virtual functions has been

   replaced with a <type>GSource *</type>.

  </para>

  </listitem>

  <listitem>

  <para>

   Sources are first created, then later added to a specific 

   <structname>GMainContext</structname>. 

  </para>

  </listitem>

  <listitem>

  <para>

   Dispatching has been modified so both the callback and data are passed

   in to the <function>dispatch()</function> virtual function.

  </para>

  </listitem>

  </itemizedlist>

  To go along with this change, the vtable for 

  <structname>GIOChannel</structname> has changed and

  <function>add_watch()</function> has been replaced by 

  <function>create_watch()</function>.

</para>

</listitem>

<listitem>

<para>

<function>g_list_foreach()</function> and 

<function>g_slist_foreach()</function> have been changed so they

are now safe against removal of the current item, not the next item.

</para>

<para>

It's not recommended to mutate the list in the callback to these

functions in any case.

</para>

</listitem>

<listitem>

<para>

<structname>GDate</structname> now works in UTF-8, not in the current locale. 

If you want to use it with the encoding of the locale, you need to convert 

strings using <function>g_locale_to_utf8()</function> first.

</para>

</listitem>

<listitem>

<para>

<function>g_strsplit()</function> has been fixed to:

  <itemizedlist>

  <listitem>

  <para>

   include trailing empty tokens, rather than stripping them

  </para>

  </listitem>

  <listitem>

  <para>

   split into a maximum of <literal>max_tokens</literal> tokens, rather 

   than <literal>max_tokens + 1</literal>

  </para>

  </listitem>

  </itemizedlist>

  Code depending on either of these bugs will need to be fixed.

</para>

</listitem>

<listitem>

<para>

Deprecated functions that got removed:

<function>g_set_error_handler()</function>, 

<function>g_set_warning_handler()</function>,

<function>g_set_message_handler()</function>, use 

<function>g_log_set_handler()</function> instead.

</para>

</listitem>

</itemizedlist>

</refsect1>

</refentry>