"Set" classes are not iterable

[awendelin-work]

The Set classes, ExperimentSet, TraceSet, ConfigurationParameterDescriptorSet, ConfigurationSet, ConfigurationSourceSet and OutputDescriptorSet are not usable by themselves as collections.

This gives you access patterns like:

from tsp.trace_set import TraceSet

traces = TraceSet([{"name": "trace0"}, {"name": "trace1"}])

for trace in traces.traces:
    print(t.name)
# trace0
# trace1

print(len(traces.traces))
# 2

This is especially inconvenient when working with experiments, since to loop over traces, you must do:

for t in experiment.traces.traces

We could make the classes easier to work with by making them implement collection interfaces.

This would give you the following access patterns instead:

from tsp.trace_set import TraceSet

traces = TraceSet([{"name": "trace0"}, {"name": "trace1"}])

for trace in traces:
    print(t.name)
# trace0
# trace1

print(len(traces))
# 2

See example in this commit.

__getitem__ could be implemented as well to allow indexing with integers (traces[0]), but it is not implemented for Python sets, so it would make the "Set" classes look less like sets.

If this kind of functionality is wanted, I can help provide patches.