I have a handy class that I use to allow me to easily add a set of "summariser" functions to a GDB pretty printer (for example, a Rect class could have an [Area] field, computed by Python). it then prints all the existing children as well, so you can see everything at once.
class SummaryAndFieldIterator:
"""
Iterator to first go through a list of summariser functions,
then display all the fields in the object in order
"""
def __init__ (self, obj, summaries):
self.count = 0
self.obj = obj;
self.summaries = summaries;
self.keys = sorted(obj.type.iterkeys())
def __iter__(self):
return self
def __next__(self):
if (self.count >= len(self.keys) + len(self.summaries)):
raise StopIteration
elif self.count < len(self.summaries):
name, retVal = self.summaries[self.count](self.obj)
# FIXME: this doesn't seem to work when a string is returned
# in retVal?
result = "[%s]" % name, retVal
else:
field = self.count - len(self.summaries)
result = self.keys[field], self.obj[self.keys[field]]
self.count += 1
return result
next = __next__
class MyObjectPrinter:
def __init__(self, val):
self.val = val
def get_int(self):
return "meaning", 42
def get_string(self):
return "hoopiness", "Forty-two"
def children(self):
return SummaryAndFieldIterator(self.val, [self.get_string])
This works very well for the summarisers which return numeric values, but for strings, it ends up displaying as an array, so that I get
NAME VALUE
myobj {..}
|-->[meaning] 42
|-->[hoopiness]
|-->[0] 'F'
|-->[1] 'o'
.....
|-->real_field 34234
This is presumably becuase the string that comes from
name, retVal = self.summaries[self.count](self.obj)
does not generate a sufficiently "stringy" gdb.Value object when it is returned by SummaryAndFieldIterator's __next__ method. Adjusting the display_hint() method of MyObjectPrinter doesn't seem to have any effect (but I doubt it would, as this is the child, not the object).
Anyone know how to return a string from the children() iterator and get it to display as a string?
