Readability: Deep nesting in linux.py LinuxBackend.__init__ engine selection

[m96-chan]

Summary

The engine selection logic in LinuxBackend.init has deeply nested try/except blocks that are hard to follow.

Location

src/proctap/backends/linux.py:1196-1272

Problem

The code has 3-4 levels of nesting with try/except blocks for fallback logic:

if detected_engine == "pipewire-native":
    try:
        self._strategy = PipeWireNativeStrategy(...)
    except RuntimeError as e:
        try:
            self._strategy = PipeWireStrategy(...)
        except RuntimeError as e2:
            self._strategy = PulseAudioStrategy(...)
elif detected_engine == "pulse":
    self._strategy = PulseAudioStrategy(...)
elif detected_engine == "pipewire":
    try:
        self._strategy = PipeWireStrategy(...)
    except RuntimeError as e:
        self._strategy = PulseAudioStrategy(...)

Impact

• Hard to follow the fallback chain
• Duplicated fallback logic
• Complex error handling

Suggested Fix

Use a strategy chain pattern:

def _create_strategy(self, pid, sample_rate, channels, sample_width, engine):
    strategies = self._get_strategy_chain(engine)
    
    for strategy_class in strategies:
        try:
            return strategy_class(pid=pid, sample_rate=sample_rate, ...)
        except RuntimeError as e:
            logger.warning(f"{strategy_class.__name__} failed: {e}")
            continue
    
    raise RuntimeError("No audio strategy available")

def _get_strategy_chain(self, engine: str) -> list[type]:
    chains = {
        "pipewire-native": [PipeWireNativeStrategy, PipeWireStrategy, PulseAudioStrategy],
        "pipewire": [PipeWireStrategy, PulseAudioStrategy],
        "pulse": [PulseAudioStrategy],
    }
    return chains.get(engine, chains["pulse"])

Labels

readability, refactor