Slot Configuration Persistence Fix for AmpleWin/Linux

[anomixer]

Hi Kelvin (@ksherlock), hope you're doing well!

I'm the contributor working on the Windows/Linux ports of Ample. Recently, a community member (@xotmatrix) pointed out a critical bug in the slot configuration logic. I have implemented a comprehensive, two-fold fix that fully aligns with the high standards of your original macOS version.

The Issues & Fixes

1. UI Level: Slot Initialization Loop

• Issue: When selecting "None" (empty string "") for a slot with default equipment, any UI refresh or machine configuration change would revert it back to the default device.
• Root Cause: The initialization code used a truthiness check: if not self.current_slots.get(slot_name):. Since an empty string "" is falsy in Python, it incorrectly assumed the slot was unconfigured and force-filled the default device.
• Fix: Updated initialize_default_slots in AmpleWin and AmpleLinux to use a key existence check instead: if slot_name not in self.current_slots:. This preserves explicit user selections (including empty strings for "None") while still auto-filling defaults for new card insertions.

2. Emulator Level: Command-Line Argument Omission

• Issue: Although "None" was preserved in the UI, when launching MAME, the default device (e.g. Disk II in slot 6) was still present.
• Root Cause: In mame_launcher.py (and also in the WASM loader for AmpleWeb), the argument builder was filtering out empty string values using a truthiness check (if option: / if (value)). As a result, the launcher completely omitted the slot from MAME's command line, letting MAME fall back to its internal hardware defaults.
• Fix: Updated build_args in AmpleWin/AmpleLinux to check if option is not None:, and buildMameArgs in AmpleWeb to check if (value !== undefined && value !== null). This ensures that explicit empty string arguments (-[slot_name] "") are generated and passed to MAME, disabling/emptying the slot device in the running emulator.

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Testing Verified

1. Selected a machine (e.g., Apple IIe / IIgs).
2. Set a default slot (e.g., Slot 6) to —None—.
3. Changed another setting (e.g., RAM size) -> Result: Slot correctly remains —None— in the UI.
4. Clicked "Start" to launch MAME -> Result: Launcher prints command line with -sl6 "" and launches successfully.
5. In MAME, pressed Tab -> Slot Devices -> Result: Slot 6 is completely Empty (Disk II interface is not loaded).
6. Plugged in a new card -> Result: Its default sub-slot devices are still automatically initialized as intended.

[xotmatrix]

Cross-posting for visibility. Apologies.

I think [anomixer's] patch only addresses half of the problem. While this patch allows one to set slot 6 to "None", when you start MAME, the Disk II interface will be present because it hasn't been explicitly disabled.

For slots that have a defined default device, they must be explicitly disabled on the command line. For instance, to empty slot 6, the command line must include -sl6 '' otherwise MAME will use the default value (diskiing Disk II interface).

[anomixer]

No worries. PR updated! Thanks again.

Cross-posting for visibility. Apologies.

I think [anomixer's] patch only addresses half of the problem. While this patch allows one to set slot 6 to "None", when you start MAME, the Disk II interface will be present because it hasn't been explicitly disabled.
For slots that have a defined default device, they must be explicitly disabled on the command line. For instance, to empty slot 6, the command line must include -sl6 '' otherwise MAME will use the default value (diskiing Disk II interface).