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<h4 class="subsection">10.9.1 Pretty-Printer Introduction</h4>

<p>When <span class="sc">gdb</span> prints a value, it first sees if there is a pretty-printer
registered for the value.  If there is then <span class="sc">gdb</span> invokes the
pretty-printer to print the value.  Otherwise the value is printed normally.

   <p>Pretty-printers are normally named.  This makes them easy to manage. 
The &lsquo;<samp><span class="samp">info pretty-printer</span></samp>&rsquo; command will list all the installed
pretty-printers with their names. 
If a pretty-printer can handle multiple data types, then its
<dfn>subprinters</dfn> are the printers for the individual data types. 
Each such subprinter has its own name. 
The format of the name is <var>printer-name</var>;<var>subprinter-name</var>.

   <p>Pretty-printers are installed by <dfn>registering</dfn> them with <span class="sc">gdb</span>. 
Typically they are automatically loaded and registered when the corresponding
debug information is loaded, thus making them available without having to
do anything special.

   <p>There are three places where a pretty-printer can be registered.

     <ul>
<li>Pretty-printers registered globally are available when debugging
all inferiors.

     <li>Pretty-printers registered with a program space are available only
when debugging that program. 
See <a href="Progspaces-In-Python.html#Progspaces-In-Python">Progspaces In Python</a>, for more details on program spaces in Python.

     <li>Pretty-printers registered with an objfile are loaded and unloaded
with the corresponding objfile (e.g., shared library). 
See <a href="Objfiles-In-Python.html#Objfiles-In-Python">Objfiles In Python</a>, for more details on objfiles in Python. 
</ul>

   <p>See <a href="Selecting-Pretty_002dPrinters.html#Selecting-Pretty_002dPrinters">Selecting Pretty-Printers</a>, for further information on how
pretty-printers are selected,

   <p>See <a href="Writing-a-Pretty_002dPrinter.html#Writing-a-Pretty_002dPrinter">Writing a Pretty-Printer</a>, for implementing pretty printers
for new types.

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