Allow "underscore" in username?

[gt-tech]

As per current github username composition rules, username can only have alphanumeric characters or a hyphen.

This turns out to be an issue when:

1. User wants to produce a java based open-source product hosted from GITHUB repo
2. User wants to use his github qualified namespace as groupId and hence by convention, his top level java package would be something like: org.github.<username>
3. User's choice of alphabetic username isn't available (taken by someone else) and he gets forced to use john**-doe instead of john_**doe (note that having numbers in username to make it unique would make the java package declaration even worse)
4. john-doe now can't be used as a package name for user's source code as Java doesn't rightfully allow "-" in package names.

Hence having "_" in username as allowed character appears to be a nice feature unless there's a technical reason blocking it to happen on github.

[cirosantilli]

converting - to _ looks like a common java naming convention: http://stackoverflow.com/questions/3179216/what-is-the-convention-for-word-separator-in-java-package-names

john-doe vs john_doe would increase confusion I think (yes, there is also johndoe)

[gt-tech]

Good point but I don't wish to debate on whether john_doe makes sense for comparing against johndoe as two separate namespaces, point well taken there's a branding decision that user has to make but i vote for this enhancement because java allows for it, DNS allows for it so unless there's a tech reason for github to not support it, i think it should. github probably wouldn't want to impose a strong opinionated thought about that someone shouldn't take john_doe if johndoe is take up someone else, that's a user choice in my view.

[smcv]

Github seems very unlikely to allow underscores, because DNS labels containing underscores are not valid Internet hostnames (reference: RFC 1123 "Requirements for Internet Hosts — Application and Support" §2.1) so Github would be unable to allocate john_doe.github.io and similar names. Yes, the DNS protocol supports labels that contain underscores, but in the contexts where they're used in practice (such as DNS SRV), they are used precisely because they are not valid in Internet hostnames, to avoid colliding with an ordinary hostname. Github also doesn't allow usernames that start with a dash, which is also an Internet hostname restriction.

Assuming github continues to only allow dashes and not underscores, in domain-name-derived contexts that only accept underscores (like D-Bus interfaces and Java packages) you can replace dashes with underscores and know that you won't cause a collision: com.github.john_doe.AwesomeApp can only belong to Github user john-doe, because john_doe can't exist. If both underscores and dashes were allowed, that reasoning would not be valid.

The standard advice that the D-Bus maintainers give for domain-name-based naming is to replace dashes with underscores, and prepend an underscore to any component that starts with a digit (which also isn't allowed, the same as in Java): so if 7-zip.org (which hits both of the problem cases) wanted to publish an archiver that communicated via D-Bus, they should call it something like org._7_zip.Archiver.

[ap0phi5]

GitHub uses underscores in its usernames already, but for its "Enterprise Managed Users" feature (part of using SSO). It's a reserved special character used internally, so can't be used by the general public.