Description

When extending a DocList with itself, the code seems to add the list recursively, causing a huge increase in the length of the list. For example, the following code produces a DocList of length 9,052,000 (I had to interrupt the execution):

from docarray import DocVec, BaseDoc, DocList
from docarray.documents.image import ImageDoc
docs = DocList[ImageDoc]([ImageDoc(url=f'http://url.com/{i}.png') for i in range(10)])
docs.extend(docs)

However, a similar operation works fine with Python lists:

l = list(range(10))
l.extend(l)
print(l)  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

Questions

• Why does DocList behave differently than Python lists in this situation?
• Are there plans to support the extend method for DocVec in the future?

Steps to reproduce

1. Run the following code snippet:

from docarray import DocVec, BaseDoc, DocList
from docarray.documents.image import ImageDoc
docs = DocList[ImageDoc]([ImageDoc(url=f'http://url.com/{i}.png') for i in range(10)])
docs.extend(docs)

2. Interrupt the execution because it hangs.

3. Observe that the resulting DocList has an enourmous length, rather than the expected 20.