[ruby-core:54314] [CommonRuby - Feature #8273] Make it possible to treat objects as falsy in order to make NullObjects more convenient

Issue #8273 has been updated by headius (Charles Nutter).


I think you might have submitted this before, but I'd like to enter my *strong* opposition to this.

* It most definitely would affect performance. Any language construct that needs to check for truthiness would suddenly have to do a method call rather than simply an identity check.
* I think it is a terrible thing that other languages like Python and PHP make it possible for the same object to be true one moment and false the next (e.g. a list that empties out or a string that is blanked). What is true should always be true; what is false should always be false.

The last point is my really strong position. I do not think it should ever be possible for the contents of an object to define its truthiness, and by extension for changes to the contents of an object to change its truthiness.
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Feature #8273: Make it possible to treat objects as falsy in order to make NullObjects more convenient
https://bugs.ruby-lang.org/issues/8273#change-38595

Author: prijutme4ty (Ilya Vorontsov)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


NullObject is quite a useful pattern. But refactoring from conditionals to null-object can be very painful because an instance of NullObject will be treated as truthy so code `... if obj` can change its behavior. It'd be great to treat such objects as falsy. Most simple and consistent solution is to make method like #to_boolean or may be #__to_bool (not to break compatibility) which returns false for NilClass and FalseClass and true otherwise unless redefined.
I don't know whether perfomance impact'll be high or no.
It's one of a few things which cannot be reimplemented using ruby itself, so there is no possibility to construct a gem as a PoC


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