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<title>Help for ROOT's Reference Guide</title>
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<div class="withshadow"><h1>Help for ROOT's Reference Guide</h1></div>
</div>
<div class="toc">
Contents
<ul class="toc">
<li class="toc"><a href="#parts">Parts of the Reference Guide</a>
   <ul class="toc">
   <li class="toc"><a href="#parts_types">Type Index</a></li>
   <li class="toc"><a href="#parts_classes">Class Index</a></li>
   <li class="toc"><a href="#parts_inh">Inheritance</a></li>
   </ul>
</li>
<li class="toc"><a href="#modules">Modules</a>
   <ul class="toc">
   <li class="toc"><a href="#modules_what">What they are</a></li>
   <li class="toc"><a href="#modules_list">List of Modules</a></li>
   <li class="toc"><a href="#modules_libdep">Modules' Library Dependencies</a></li>
   </ul>
</li>
<li class="toc"><a href="#class">Class Reference</a>
   <ul class="toc">
   <li class="toc"><a href="#class_sect">Sections</a></li>
   <li class="toc"><a href="#class_links">Link Box</a></li>
   <li class="toc"><a href="#class_info">Info Box</a></li>
   <li class="toc"><a href="#class_mem">List of Data and Function Members</a>
      <ul class="toc">
      <li class="toc"><a href="#class_mem_disp">Display Options</a></li>
      <li class="toc"><a href="#class_mem_access">Access (public / protected / private)</a></li>
      <li class="toc"><a href="#class_mem_inh">Inheritance</a></li>
      </ul>
   </li>
   <li class="toc"><a href="#charts">Class Charts</a>
      <ul class="toc">
      <li class="toc"><a href="#charts_inh">Inheritance</a></li>
      <li class="toc"><a href="#charts_inhmem">Inherited Members</a></li>
      <li class="toc"><a href="#charts_inc">Includes</a></li>
      <li class="toc"><a href="#charts_lib">Libraries</a></li>
      </ul>
   </li>
   <li class="toc"><a href="#memfunc">Member Function Documentation</a></li>
   </ul>
</li>
</ul>
</div>
<div style="clear:both;"></div>

<h2><a id="parts"></a>Parts of the Reference Guide</h2>

<h3><a id="parts_types"></a>Type Index</h3>
All basic types and typedefs are documented in the <a href="./ListOfTypes.html">Type Index</a>.

<h3><a id="parts_classes"></a>Class Index</h3>
All classes and namespaces are listed alphabetically in the <a href="./ClassIndex.html">Class Index</a>,
along with a short info of what they are used for.
You can jump to a class's entry using the shortcuts ontop of the page.
They are optimized for quick access: they are distributed evenly, and short.
Classes are grouped in modules; these, too, are listed ontop of the list of classes.

<h3><a id="parts_inh"></a>Inheritance</h3>
All classes along with their derived and base classes are shown in the 
<a href="./ClassInheritance.html">Class Hierarchy</a>.
The documentation for each class also shows the inheritance diagram.
The class hierarchy is meant to give an overview of available classes
and their relations.

<h2><a id="modules"></a>Modules</h2>
<h3><a id="modules_what"></a>What they are</h3>
Classes are grouped into modules. For ROOT, this is done on a per-directory basis:
each module corresponds to a sub-directory. In other cases one module might represent
one library. Either way, modules are meant to combine similar or related classes, 
allowing users to find classes close by context. If you need some functionality that
you cannot find in a class you know, you might want to check for classes in the same
module - maybe one of them does what you need.

<h3><a id="modules_list"></a>List of Modules</h3>
Modules are listed ontop of the <a href="./ClassIndex.html">Class Index</a> and as part
of the <a href="./LibraryDependencies.html">Library Dependencies Chart</a>.

<h3><a id="module_libdep"></a>Modules' Library Dependencies</h3>
Each module is assumed to be part of a library. The dependencies of libraries are 
not only relevant for linking, but often reflect also the contextual dependencies.
The dependencies of all modules are shown in the
<a href="./LibraryDependencies.html">Library Dependencies Chart</a>.

<h2><a id="class"></a>Class Reference</h2>
Pages like the one for <a href="http://root.cern.ch/root/html/TH2.html">TH2</a> are 
class references. They document the use and functionality of a class.

<h3><a id="class_sect"></a>Sections</h3>
Each class reference page has a class documentation, which documents what the class
can be used for, and gives hints on how to use it. This allows you to figure out 
whether a certain class is appropriate for what you try to do. The page then lists 
all available members; they define a class's functionality and its interaction with 
your code. The next item is a tabbed set of charts, which allow you to study the
class's inheritance diagram, what members get inherited from where, and which members
are re-implemented, which files get indirectly included by including the class's
header, and which libraries this class depends on. The remainder of the page contains
the functions' documentation. And there is a little tool box floating around, which
gives you some display options and a link to this help page.

We will now go through all these parts in detail.

<h3><a id="class_links"></a>Link Box</h3>
On the top of the page you can find a list of links. The first line contains the current
"location", giving the home page, the module name, and the class name.
The second line links to generic pages, like ROOT's home page, the 
<a href="#parts_classes">Class Index</a>, and the <a href="#parts_inh">Class Hierarchy</a>.
The last line allows you to jump to the sections of the current page and a colored
version of the class's header and source file.

<h3><a id="class_info"></a>Info Box</h3>
There is a little info box, usually floating on the right side of the page
(update your browser if it's not). It shows the name of the class you are currently
looking at, which library you have to link against to get access to the class, and
which header file you have to #include.

It also contains options that influence how
the list of members is displayed. you can show or hide non-public methods. If you
just want to use ROOT you should hide them - you cannot access protected or private
members anyway. And you can select whether member that are inherited from a base class
should be shown. Again, if you just want to use ROOT you should probably show them,
as you often want to use them whether they are defined in the current class or in one
of its base classes. Whatever you set these options to should be stored in a cookie,
so you will have the same setting next time you look at the class documentation.

The two links in the bottom of the box get you to the top of the page and to this help
page. You can hide the info box by clicking on the little "-" in the top right corner
of the box, and show it again by clicking on the "+".

<h3><a id="class_mem"></a>List of Data and Function Members</h3>
<p>The central part of a class are its members. Some are available to you; some
are hidden from you, because they are only meant to be used internally.
As an example, a class might allow you to set, access, and print its values, or store 
them into a file. 
Because methods should have reasonable names, often the method name itself is already 
a hint on what it does.
If you want to get a <a href="http://root.cern.ch/root/html/TNamed.html">TNamed</a>'s
name, you will immediately see TNamed::GetName() in its list of functions.
A click on this name will send you to the documentation for the method.
If you <a href="class_mem_disp">enabled the display of inherited members</a> you will see 
some members with a class name prefix. It tells you where this method has been defined.</p>

<h4><a id="class_mem_disp"></a>Display Options</h4>
The <a href="#class_info">info box</a> contains options that influence how
the list of members is displayed: you can e.g. show or hide non-public methods. If you
just want to use ROOT you should hide them - you cannot access protected or private
members anyway. And you can select whether member that are inherited from a base class
should be shown. Again, if you just want to use ROOT you should probably show them,
as you often want to use them whether they are defined in the current class or in one
of its base classes. Whatever you set these options to should be stored in a cookie,
so you will have the same setting next time you look at the class documentation.

<h4><a id="class_mem_access"></a>Access (public / protected / private)</h4>
Not all members are available to everyone (check any C++ introduction to learn why).
Public members have a green bar on their left, protected ones have a yellow one, and 
private members are marked with a red bar. Of course you won't see any protected or
private members if you hide them in the <a href="#class_mem_disp">display options</a>.

<h4><a id="class_mem_inh"></a>Inheritance</h4>
You can often access members of a class's base classes, just as if they are defined
in the derived class. A <a href="http://root.cern.ch/root/html/TH1.html">histogram</a>,
for example, has a name, and you can access it using GetName() as defined in its base 
class <a href="http://root.cern.ch/root/html/TNamed.html">TNamed</a>. If you want to see
all available members, and not just the ones defined in the current class, in the
<a href="#class_mem_disp">display options</a>. They will be prefixed with the name of
the class they are defined in.

<h3><a id="charts"></a>Class Charts</h3>
The class charts are shown in a tabbed box; click on the names ontop to select a tab.

<h4><a id="charts_inh"></a>Inheritance</h4>
This chart shows the inheritance hierarchy for the current class. Arrows point to
base classes. You can click the classes to get to their reference page.

<h4><a id="charts_inhmem"></a>Inherited Members</h4>
The second chart shows a list of all members of all base classes. You can see at what
level they are defined or at what level they are defined. Members that are accessible
(public) have a green background, protected ones have a yellow background, and private
members have a red background. Members with a dark gray background are re-implemented
or hidden by a derived class.

<h4><a id="charts_inc"></a>Includes</h4>
The Includes chart shows which files are indirectly included by including the class's
header. Most headers will #include some files, so by #including that header you also 
#include the #included files, and so on. A illegible chart often means you should
read a bit on the C++ trick known as "forward declaration". Including too many headers
has some nasty consequences, like compile time, additional dependencies, etc.

<h4><a id="charts_lib"></a>Libraries</h4>
Each class is assumed to be in a library. That library might depend on other libraries.
The fourth chart shows the dependencies of these libraries. You will need to link against
all of these if you write your own program.

<h3><a id="memfunc"></a>Member Function Documentation</h3>
Each function should be documented by the developer of the class. The documentation can
contain HTML, pictures, and example code. It should explain what the function does,
what it expects as parameters, what it returns, and what can make it fail. Short functions
can have their source displayed. You can click on the function name to jump to a
colored version of the function's source.

<p>&nbsp;</p>
<br />
<!--SIGNATURE-->
<em>Author: <a href="http://consult.cern.ch/xwho?Axel.Naumann">Axel Naumann</a></em><br />
<em>Last update: 2007-01-12</em><br />
<em>Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.</em><br />
<hr />
<h4>
This page has been hand crafted. If you have any comments or suggestions about the page layout send a mail to <a href="mailto:rootdev@cern.ch">ROOT support</a>, or contact <a href="mailto:rootdev@cern.ch">the developers</a> with any questions or problems regarding ROOT.
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