“regular expression” in “Create class” does not support full RE syntax

[kaimikael]

What's wrong?

The documentation for “Create class” says: “Substring: regex-defined substring that will match the values from the above-defined attribute”
I took this to mean that you can define an arbitrary regular expression in the Substring field, but as can be seen in the attached screenshot, when I entered .*—which should match any string—I got no matches at all. I have played around with the input and it seems that what you enter is actually treated as a literal substring to be matched. If this is the intended behaviour, then please treat this as a feature request:
I’d like the Substring field to support the full Python regular expression syntax, including \number, so that matched substrings can be used in the Name section. In my concrete case I want to enter the Substring (.*) \([12]\) and use \1 in the Name field, so that the item Belgium (2) is renamed Belgium.

Failing that, “regex-defined” should be deleted from the documentation text.

How can we reproduce the problem?

Input any data. Connect to a “Create Class” widget. Select any string feature. Enter .* as Substring. Note that no strings are matched.

What's your environment?

• Operating system: macOS 15.2
• Orange version: 38.8.0
• How you installed Orange: From https://download.biolab.si/download/files/Orange3-3.38.0-Python3.10.11-x86_64.dmg

[janezd]

Documentation is wrong. This widget always matched just substrings, not regular expressions.

But instead of fixing the documentation, we could fix the widget. :) Matching regular expressions sounds useful and should be trivial to implement. The user would control it with a checkbox. The widget has plenty of space for it.