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From: Alexander E. Fischer on 7 Jul 2010 08:56
I noticed that at least some of the standard libs use global methods to
provide some kind of shortcut to the actual new method. For example the
excellent Pathname class' objects can be generated either by

Pathname.new('/home/someone')

or simply through

Pathname('/home/someone')

The latter example is possible through a method on the Kernel module,
which is named capitalized.

module Kernel
def Pathname(path)
Pathname.new(path)
end
end

I think this shortcut is really useful, but also very ugly in its
implementation. If more classes do this, especially classes outside of
the class library, the global method namespace, which is already filled
with a lot of things, will become overcrowded. In the end there will be
naming collisions because of a lack of sub-namespacing. To discourage
this behaviour I would recommend to remove those global methods and
implement the whole thing in a slightly different fashion:

class Pathname
def self.[](path)
new(path)
end
end

This implementation would allow this:

Pathname['/home/someone']

which is still very near to the current variant but more eco-friendly in
my opinion.

If there is no big problem about this (tell me, if you see one!) I'm
willing to add the new methods in affected classes (at least the standard
lib classes Complex and Rational use this, too) and add an deprecation
warning in the old method. Then I would submit this as a patch.
From: Joel VanderWerf on 7 Jul 2010 13:11
Alexander E. Fischer wrote:
> Pathname['/home/someone']

I like this pattern. Note that there is some precedent in the core:
Array, Hash, and Struct classes all have a [] class method (not
necessarily equivalent to #new).

It's also fairly well used in the stdlib and the gems I happen to have
installed:

$ ri '[]' | grep -oP '\S+::\[\]\S+'
WEBrick::HTTPStatus::[],
Dir::[],
Array::[],
Hash::[],
Set::[],
Matrix::[],
Vector::[],
Generators::AllReferences::[],
Net::SSH::Version::[],
YAML::Pairs::[],
YAML::Omap::[],
Webby::Filters::[],
Webby::Filters::[],
CodeRay::FileType::[],
Pure::[],
Rake::Task::[],
Rake::FileList::[],
JSON::[],
JSON::[],
MIME::Types::[],
OrderedHash::[],
NArray::[],
Nokogiri::EncodingHandler::[],
Nokogiri::HTML::ElementDescription::[],
Nokogiri::CSS::Parser::[]=,
Nokogiri::CSS::Parser::[],
MultiRBTree::[],


But note that some of these, like Dir#[], are not the same as #new.

But I don't know how easy it will be to convince people to live with the
deprecation warning for Pathname et al. I wouldn't mind it.

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