Notes posted by stevecj

Getting the return value from the underlying method of an Enumerator

This is documented in the example code, but easy to miss.

When you get an Enumerator using #to_enum(:method_name, …), you can get all of the yielded values using #next, but not the value that is finally returned.

That value can be retrieved via the #result attribute of the StopIteration exception object that is raised when calling #next after the underlying method has returned.

See also ConditionVariable

If you need to and processing with respect to a particular resource between 2 or more threads in more complicated ways, it is likely that ConditionVariable is what you’re looking for.

Reports originally defined method names, not invoked names in Ruby 1.9.x

In Ruby 1.8.7, the reported method names were those of the methods actually invoked, so if #b was an alias for #a, and #b was called, it would be reported as “… in `b’”. In Ruby 1.9, the same invocation is now reported as “… in `a’”.

Unfortunately, this change disables the hack that could formerly be used to create a variant of __method__ that returns the method as actually invoked. The new __callee__ method is no help with that, because it is currently synonymous with __method__.

__callee__ and __method__ both return symbol when originally defined, not current

There has been some indication that __callee__ is intended to return the symbol with which the method was actually invoked, whereas __method__ returns name with which the method was originally defined, but __callee__ actually behaves identically to __method__ in Ruby 1.9.1 1.9.2, and 1.9.3.

This distinction is meaningful, because methods can be aliased after they are created.

In Ruby 1.8.7, it was possible (though) not convenient to get the name of the method as actually invoked, by calling another method that extracts the name from caller.first. Even that hack no longer works in Ruby 1.9 though, since it will return the originally defined method name as well.