[ruby-talk:14956] Re: An Attempt at Versioning

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Je Lundo 07 Majo 2001 13:53, vi skribis:
> I have this prototype for versioning. Tell me what you think of it.

The more I look at this, the more I like it.  I've been needing this in Java 
for a while.

What do you think about a version which allows for intelligent loading, so 
that multiple versions of a module/library can exist on a platform at once?  
For example:

def require(file, proc)
	...
		found = getAllVersions(file).reverse.find { |inst|
			proc.call $require_versions[inst]
		}
		if found.nil? then raise VersionError.new filename,version,me[2]
	...
end

Where getAllVersions finds all files in the search path by the name 
#{file}(_(\d+(\.\d+)*))?\.rb, in order of the version numers.  Ergo, we'll 
always get the newest compatible version of the library.

I mention this because as Ruby ages, it is going to encounter the conflicting 
library version problems that are plaguing Java at the moment.  Some older 
apps will require an earlier version of a library than newer apps require, 
and tracking these different library versions will become difficult.  Linux 
manages this by allowing multiple versions of the same library to co-exist, 
and I believe that Ruby should, as well.  Mathieu's code is a good start of a 
proper library versioning system.

For that matter, the Ruby library installation mechanism could be extended to 
allow library authors to intelligently manage their libraries.  For example, 
say I install the brand new SuperUtils package 1.0 on my system.  The 
installation package has some rules file which specifies:

	install_rules 1,0
		compatible 0,0

This gets installed as superutils_1.0.rb.

The SuperUtils auther releases a non-backwards compatible version 2.0.  This 
gets installed  by the inconcurrently beside the 1.0 version on my system:

	install_rules 2,0
		compatible 2,0

so that I have superutils_1.0.rb and superutils_2.0.rb.

Soon after, the author releases version 2.1, 2.2, and 2.3 in rapid 
succession, which are all backwards compatible with version 2.0.  I only grab 
the 2.3 version

	install_rules 2,3
		compatible 2,0

so now I have superutils_1.0.rb and superutils_2.3.rb.

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