ZDoom

Can we please get a pointer to throw unused output into?

The specific example I've got in mind is the bool that is called by A_SpawnItemEx. Literally every time I've ever needed the output of this function it was to get the actor, and the likelihood of it being false (assuming I wasn't using SXF_NOCHECKPOSITION) was low enough that simply checking for that actor being null was sufficient.

Yet every single time I do this I need to go out of my way to define a new local variable that serves no purpose except to fulfil this requirement, or do some really gross hack involving a flag that I figure that particular calling actor would never use.

It's a minor thing, but it does lead to a lot of needless clutter.

Normally that shouldn't be necessary, but the return values for this function are definitely in the wrong order.

Unfortunately we can't change that without breaking who knows how many mods.

JavaScript ES6 destructuring assignment (see "Ignoring some returned values") syntax allows developers to discard unnecessary values.

For example, a line of code from paledit:

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let [start,] = this.subRanges[subRangeIdx].sorted();

Heh, I run into this all the time. It's "cosmetic," but a bit of a PITA.

A suggestion: since there's already precedent for deprecating+renaming functions (e.g. A_FireCustomMissile to A_FireProjectile, albeit that was for a more serious reason) and the name "A_SpawnItemEx" is pretty antiquated anyway ("Ex" suffix, plus it spawns any actor, not just an "Item"), perhaps let's make an "A_SpawnActor" that has the same parameters & functionality but returns the Actor only. Nice n' clean.

[Also yes, we could DIY this mostly by implementing a proxy function, but it'd be nice for everyone to not to have to. ;]

C++11 has:

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int ret;
std::tie(ret, std::ignore) = call_returns_a_pair_or_tuple_of_two();

C++17 adds structured bindings:

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auto [ret, ] = call_returns_a_struct_or_array_of_two();

(I think an empty name is okay for ignored elements, I forget).

Xaser wrote:Heh, I run into this all the time. It's "cosmetic," but a bit of a PITA.

A suggestion: since there's already precedent for deprecating+renaming functions (e.g. A_FireCustomMissile to A_FireProjectile, albeit that was for a more serious reason) and the name "A_SpawnItemEx" is pretty antiquated anyway ("Ex" suffix, plus it spawns any actor, not just an "Item"), perhaps let's make an "A_SpawnActor" that has the same parameters & functionality but returns the Actor only. Nice n' clean.

[Also yes, we could DIY this mostly by implementing a proxy function, but it'd be nice for everyone to not to have to. ;]

Good suggestion. That's how I'd solve it.
For leaving out single arguments in such a case, unfortunately some more work on the parser and the code generation is needed, and right now I don't have time for that.

Empty names for arguments and such sounds like a good idea to me. Unrealscript does that when you want to skip some arguments in function calls and leave them default.

Is "A_Spawn" used for anything that could result in a conflict? I see only one instance of it in something about DEH aliases but I have no idea what the implications are.

Matt wrote:Is "A_Spawn" used for anything that could result in a conflict? I see only one instance of it in something about DEH aliases but I have no idea what the implications are.

Yes, it's an MBF codepointer. See CreateSpawnFunc() in src/d_dehacked.cpp for the internal side of the implementation.