Report a useful version number

[Jonathan Hartley]

When users look in the store at our snap, or consult "snap info universal-ctags", they see version numbers of the form:

• major = 0
• minor = 2
• patch = (hyphen separated):
  • year
  • month
  • date
  • first 8 chars of universal-ctags commit from which this build was made

eg. 0.2.2018-09-21-39e840e6

[Jonathan Hartley]

When users run ctags --version on the installed snap, the reported version information includes both the 8 character git commit and the date of compilation, so these will be visibly comparable.

[Jonathan Hartley]

I'm wondering about whether to make the timestamp embedded in the version contain the hour-minute-second too, so that multiple releases made on the same day, from different commits, will be ordered correctly.

• 0.2.2019-09-21-39e840e6

vs

• 0.2.2019-09-21-21-43-55-39e840e6

[Jonathan Hartley]

"Snap versions consist of upper- and lower-case alphanumeric characters, as well as periods, colons, plus signs, tildes, and hyphens. They cannot begin or end with a period, colon, or hyphen. They cannot begin with plus sign, tilde."

So we could do

• 0.2.2019-09-21+21:43:55+39e840e6

[Jonathan Hartley]

$ git show --format="%ci %h" -s | cut -d' ' -f1-2,4 | tr ' ' '+'
2019-09-20+13:49:53+39e840e6