DDC-2783: EntityManager#transactional() support for non-truthy values

[doctrinebot]

Jira issue originally created by user chebba:

The problem:
Any response from transactional callback which is evaluated to *false* (empty array, empty string, 0, null, etc) becomes true

$return = call*user*func($func, $this);

$this->flush();
$this->conn->commit();

return $return ?: true;

There is the old resolved issue DDC-1336, which describes this behavior.
@return tag is clear now.

@return mixed Returns the non-empty value returned from the closure or true instead

But this logic is blowing mind and leading to unexpectable results. The expected behavior is just return callback result, i don't see any good use cases for current implementation.

It requires a BC break. Can the deprecation process be started to change this behaviour in few major releases?

[doctrinebot]

Comment created by stof:

I agree that this makes the method hard to use. And I don't undertstand why it would replace the return value.

What was the intention for this Benjamin ?

[doctrinebot]

Comment created by @guilhermeblanco:

[_{stof] [}beberlei] I'm considering to remove the ternary and always return the callback result.
What do you think? It seems like a minor BC break, but would like to get more feedback around this.

[doctrinebot]

Comment created by @Ocramius:

[~guilhermeblanco] this was already refused before because of the BC break.

[fracz]

Is there any chance to change this strange behavior?

[Majkl578]

@fracz Yes, it's aready been done for 3.0 in #6147.
Ping @Ocramius, this could be marked as BC break & done & 3.0 milestone, I guess?

[lcobucci]

@fracz did you see #6147?

[fracz]

I have not. Thank you for rapid response!

[Ocramius]

Closing as per #6147 👍