Infinite loop when iterating over group objects while adding new objects

[PierreRaybaut]

Infinite loop when iterating over group objects while adding new objects

Description

When developing a DataLab plugin that iterates over object IDs from a group and adds new objects during the iteration, an infinite loop occurs.

Steps to Reproduce

1. Create a plugin that retrieves object IDs from a group using get_object_ids_from_group_title()
2. Iterate over those IDs and add new objects to the panel during the loop
3. The loop never terminates

Example code pattern that triggers the issue:

def compute_Fourier_forgroup(self, group) -> None:
    sig_ids = self.get_object_ids_from_group_title(group)
    for ids in sig_ids:
        sign = self.main[ids]
        # ... processing ...
        FFT_sign = sips.fft(zsign)
        self.signalpanel.add_object(FFT_sign)  # Adding object causes infinite loop

Workaround

Wrapping the result with list() prevents the issue:

sig_ids = list(self.get_object_ids_from_group_title(group))

Root Cause

The ObjectGroup.get_object_ids() method in datalab/objectmodel.py returns a direct reference to its internal __objects list instead of a copy:

def get_object_ids(self) -> list[str]:
    """Return object ids in group"""
    return self.__objects  # Direct reference - problem!

When new objects are added to the group during iteration, the internal list grows, causing the iterator to never reach the end.

Solution

Return a copy of the list instead of the direct reference:

def get_object_ids(self) -> list[str]:
    """Return object ids in group"""
    return list(self.__objects)  # Safe copy

Impact

• Severity: High - causes application to hang
• Affected versions: All versions prior to fix
• Affected users: Plugin developers iterating over groups while adding objects