##### 23.2.2.22 Program Spaces In Python

A program space, or progspace, represents a symbolic view of an address space. It consists of all of the objfiles of the program. See Objfiles In Python. See program spaces, for more details about program spaces.

The following progspace-related functions are available in the `gdb` module:

— Function: gdb.current_progspace ()

> This function returns the program space of the currently selected inferior. See Inferiors and Programs.

— Function: gdb.progspaces ()

> Return a sequence of all the progspaces currently known to gdb.

Each progspace is represented by an instance of the `gdb.Progspace` class.

— Variable: Progspace.filename

> The file name of the progspace as a string.

— Variable: Progspace.pretty_printers

> The `pretty_printers` attribute is a list of functions. It is used to look up pretty-printers. A `Value` is passed to each function in order; if the function returns `None`, then the search continues. Otherwise, the return value should be an object which is used to format the value. See Pretty Printing API, for more information.

— Variable: Progspace.type_printers

> The `type_printers` attribute is a list of type printer objects. See Type Printing API, for more information.

— Variable: Progspace.frame_filters

> The `frame_filters` attribute is a dictionary of frame filter objects. See Frame Filter API, for more information.

One may add arbitrary attributes to `gdb.Progspace` objects in the usual Python way. This is useful if, for example, one needs to do some extra record keeping associated with the program space.

In this contrived example, we want to perform some processing when an objfile with a certain symbol is loaded, but we only want to do this once because it is expensive. To achieve this we record the results with the program space because we can't predict when the desired objfile will be loaded.

         (gdb) python
         def clear_objfiles_handler(event):
             event.progspace.expensive_computation = None
         def expensive(symbol):
             """A mock routine to perform an "expensive" computation on symbol."""
             print "Computing the answer to the ultimate question ..."
             return 42
         def new_objfile_handler(event):
             objfile = event.new_objfile
             progspace = objfile.progspace
             if not hasattr(progspace, 'expensive_computation') or \
                     progspace.expensive_computation is None:
                 # We use 'main' for the symbol to keep the example simple.
                 # Note: There's no current way to constrain the lookup
                 # to one objfile.
                 symbol = gdb.lookup_global_symbol('main')
                 if symbol is not None:
                     progspace.expensive_computation = expensive(symbol)
         gdb.events.clear_objfiles.connect(clear_objfiles_handler)
         gdb.events.new_objfile.connect(new_objfile_handler)
         end
         (gdb) file /tmp/hello
         Reading symbols from /tmp/hello...done.
         Computing the answer to the ultimate question ...
         (gdb) python print gdb.current_progspace().expensive_computation
         42
         (gdb) run
         Starting program: /tmp/hello
         Hello.
         [Inferior 1 (process 4242) exited normally]