Re: LPeg 0.10

[Nick Gammon <nick@...>]

On 10/11/2010, at 1:36 PM, Miles Bader wrote:

> Nonetheless, it's a very standard format for version numbers.

Yes I understand.

However the documentation for lpeg.version says:

> lpeg.version ()
> 
> Returns a string with the running version of LPeg. 

This is inconclusive about how to compare versions. 

My example:

  print ("0.10" > "0.9") --> false

Norbert Kiesel's comparison:

  test('0.9', '0.10') --> 0.9 0.10 -1

We get different results, and just assuming that you should compare in a certain way is likely to cause grief, as indeed it did recently with the LuaJSON library.


If I may suggest, the documentation could be amended to say something like:

"Versions should be compared, not as pure strings (nor as a decimal number), but using standard "version" comparisons where each group of digits is to be considered individually. More information: http://semver.org/";

By way of comparison, SQLite3 provides both a string version (printable form) and a numeric version along the lines of 3007004 for version 3.7.4.  The numeric version can be directly compared without any mucking around with special comparison functions.


- Nick