double-under | node.js shared objects | Runtime Evironment library

I'm trying to extract substrings in a character vector up to a double-underscore i.e. "__"

For example, let's say that I have the following data.table:

To tell the compiler to exclude a function from the address sanitizer, the documentation for both gcc and clang say to use an __attribute__ called no_sanitize like this:

Probably a nube question but I have a line of code:

var c = message.substring(i, i + 1);

It works but in the new Google App Script editor, the string property "substring" has a double-underline under it, which seems to suggest that it's wrong, but it actually works!

"Show Fixes" gives me only two options - to ignore the "error" or disable checking, neither of which seems like what I want to do. Any ideas?

Rails uses it here in rails/activesupport/lib/active_support/inflector/inflections.rb

It used to be possible to set internal functions like __len__() at runtime. Here is an example:

I realize that __contains__ is the the "in" operator. I also realize that, by default "not in" is the negation of __contains__. However, a lot of the python documentation lists "not in" as if it is a separate operator from "in." Is __contains__ like __eq__ and __ne__ where there are two operators, one usually the negation of the other? if so, what is the correct double-underscore ____ to use?

I have a table with a file name column where various vendors named files differently. So there is a filename with a last, first, middle name in the file with various characters separating the name. Some have a comma + space, comma with no space, spaces between words, no spaces between words, an underscore, two underscores etc.

What are some good ways this be extracted to the desired result? (It's a one-time data conversion, doesn't have to be pretty.)

What I've tried is in the sample code below, using various substring/charindex combinations

Filename sample: (note the commas,spaces,no-spaces,underscores, double-underscores)

Desired Results:

Sample Code / Test Data (in a temp table)

In Python, there are conventions for single leading underscore, double leading underscore, double leading + double trailing underscore, and single trailing underscore. Many of those are outlined in the answers at What is the meaning of a single- and a double-underscore before an object name?.

But what is the meaning or convention for single leading + single trailing underscore? I've first seen their use in the enum module:

8.13.15.3.2. Supported _sunder_ names

• _name_ – name of the member
• _value_ – value of the member; can be set / modified in new
• _missing_ – a lookup function used when a value is not found; may be overridden
• _ignore_ – a list of names, either as a list() or a str(), that will not be transformed into members, and will be removed from the final class
• _order_ – used in Python 2/3 code to ensure member order is consistent (class attribute, removed during class creation)
• _generate_next_value_ – used by the Functional API and by auto to get an appropriate value for an enum member; may be overridden

I have not seen such single-leading-single-trailing underscore sunder names before. Are they treated in any special way, or otherwise have an implied meaning that is distinct from any of the other underscore-related naming conventions? How are they different from having no underscores at all?

I'm hoping to get some clarification here(New to python). So I'm trying to call out a large VLAN, then break that VLAN into a few smaller subnets based on some criteria.

In looking at all the class methods I see a method called _prefixlen. Looking at other posts in stackoverflow, it looks like generally the _methods are generally private module methods, and are not brought in when calling import. Source here. However, using this method it does allow me to change the prefixlen.