bt2: Add bindings for trace classes
[babeltrace.git] / tests / bindings / python / bt2 / utils.py
1 import bt2
2
3 # Run callable `func` in the context of a component's __init__ method. The
4 # callable is passed the Component being instantiated.
5 #
6 # The value returned by the callable is returned by run_in_component_init.
7
8 def run_in_component_init(func):
9 class MySink(bt2._UserSinkComponent):
10 def __init__(self, params):
11 nonlocal res_bound
12 res_bound = func(self)
13
14 def _consume(self):
15 pass
16
17 g = bt2.Graph()
18 res_bound = None
19 g.add_component(MySink, 'comp')
20
21 # We deliberately use a different variable for returning the result than
22 # the variable bound to the MySink.__init__ context and delete res_bound.
23 # The MySink.__init__ context stays alive until the end of the program, so
24 # if res_bound were to still point to our result, it would contribute an
25 # unexpected reference to the refcount of the result, from the point of view
26 # of the user of this function. It would then affect destruction tests,
27 # for example, which want to test what happens when the refcount of a Python
28 # object reaches 0.
29
30 res = res_bound
31 del res_bound
32 return res
33
34 # Create an empty trace class with default values.
35
36 def get_default_trace_class():
37 def f(comp_self):
38 return comp_self._create_trace_class()
39
40 return run_in_component_init(f)
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