# Global method usage in standard libs

**URL:** <https://www.ruby-forum.com/t/global-method-usage-in-standard-libs/191204>\
**Category:** Ruby\
**Created:** [July 7, 2010, 3:02pm UTC](https://www.ruby-forum.com/t/global-method-usage-in-standard-libs/191204 "2010-07-07T15:02:12Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Alexander\_ESFische](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/b9bd4f/32.png) [@Alexander\_ESFische](https://www.ruby-forum.com/u/Alexander_ESFische)\
**Post date:** [July 7, 2010, 3:02pm UTC](https://www.ruby-forum.com/t/global-method-usage-in-standard-libs/191204/1 "2010-07-07T15:02:12Z")

</div>

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.  
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.

---

<div class="post-metadata">

**Author:** ![Alexander\_ESFische](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/b9bd4f/32.png) [@Alexander\_ESFische](https://www.ruby-forum.com/u/Alexander_ESFische)\
**Post date:** [July 7, 2010, 7:12pm UTC](https://www.ruby-forum.com/t/global-method-usage-in-standard-libs/191204/2 "2010-07-07T19:12:17Z")

</div>

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.