Info Catalog gdb: Guile Pretty Printing API gdb: Guile API gdb: Writing a Guile Pretty-Printer

gdb: Selecting Guile Pretty-Printers

 
 23.3.3.9 Selecting Guile Pretty-Printers
 ........................................
 
 There are three sets of pretty-printers that GDB searches:
 
    * Per-objfile list of pretty-printers (Objfiles In Guile).
    * Per-progspace list of pretty-printers (Progspaces In
      Guile).
    * The global list of pretty-printers (Guile Pretty Printing
      API).  These printers are available when debugging any inferior.
 
    Pretty-printer lookup is done by passing the value to be printed to
 the lookup function of each enabled object in turn.  Lookup stops when a
 lookup function returns a non-'#f' value or when the list is exhausted.
 Lookup functions must return either a '<gdb:pretty-printer-worker>'
 object or '#f'.  Otherwise an exception is thrown.
 
    GDB first checks the result of 'objfile-pretty-printers' of each
 '<gdb:objfile>' in the current program space and iteratively calls each
 enabled lookup function in the list for that '<gdb:objfile>' until a
 non-'#f' object is returned.  If no pretty-printer is found in the
 objfile lists, GDB then searches the result of
 'progspace-pretty-printers' of the current program space, calling each
 enabled function until a non-'#f' object is returned.  After these lists
 have been exhausted, it tries the global pretty-printers list, obtained
 with 'pretty-printers', again calling each enabled function until a
 non-'#f' object is returned.
 
    The order in which the objfiles are searched is not specified.  For a
 given list, functions are always invoked from the head of the list, and
 iterated over sequentially until the end of the list, or a
 '<gdb:pretty-printer-worker>' object is returned.
 
    For various reasons a pretty-printer may not work.  For example, the
 underlying data structure may have changed and the pretty-printer is out
 of date.
 
    The consequences of a broken pretty-printer are severe enough that
 GDB provides support for enabling and disabling individual printers.
 For example, if 'print frame-arguments' is on, a backtrace can become
 highly illegible if any argument is printed with a broken printer.
 
    Pretty-printers are enabled and disabled from Scheme by calling
 'set-pretty-printer-enabled!'.  Guile Pretty Printing API.
 

Info Catalog gdb: Guile Pretty Printing API gdb: Guile API gdb: Writing a Guile Pretty-Printer