Issue #14951 has been updated by nobu (Nobuyoshi Nakada).


danga (Dan Garubba) wrote:
> Sure. In my day job, I write testing code. So I've written an expression like:
> 
> ~~~ ruby
> raise MyError unless in_scenario_x? == actions_performed_for_scenario_x?
> ~~~
> 
> To express: "raise an error unless the actions are performed for scenario X if and only if we are in scenario X".

The code and the explanation differ.

If the former is correct, the latter should be:
"raise an error unless the actions are performed for scenario X and we are in scenario X, or the actions aren't performed for scenario X and we aren't in scenario X".

If the latter is correct, the former should be:
~~~ruby
raise MyError unless in_scenario_x? && actions_performed_for_scenario_x?
~~~


----------------------------------------
Feature #14951: New operator to evaluate truthy/falsy/logical equivalence
https://bugs.ruby-lang.org/issues/14951#change-73257

* Author: danga (Dan Garubba)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
I propose adding a new operator for truthy/falsy equivalence, similar to what was proposed on https://bugs.ruby-lang.org/issues/13067, but with new syntax. The main purpose would be for writing expressions for logical equivalence (i.e., "if and only if" relationships) that only considers the truthiness the operands. Since predicate methods like `File#size?` and operators like `=~` follow truthy semantics without returning the `true` and `false` singletons, using them in logical expressions that evaluate for logical equivalence can be error-prone without the proper return type awareness and conversions. This proposed operator would be equivalent to `!!a == !!b`, but I feel that a new operator would be more concise and more expressive of the concept of logical equivalence.

Attached is a prototype implementation of the operator as '=?'.
 

---Files--------------------------------
teq.patch (3.47 KB)


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