[pigeon] Support static constant values

I'm looking to define constant values to represent error codes.

I can't find any documentation on what happens to any constants that are defined and where they should be defined.

I'm going to try and add them to the class defined for @HostApi .

This does seem to suggest that the documentation should cover off what is permitted in the HostApi and FlutterApi classes.

After testing it looks like constants are not supported.

I would suggest this is a pretty important implementation detail otherwise we will be left to maintain matching constants list on both sides of the wire.

Support for static constants would seem fairly straight forward and solve a large class of problems (including obviating the short term need for enum support).

/// The collection of methods we use to call into the platform code.
@HostApi()
abstract class SoundsToPlatformApi {
  /// The list of specific errors that can be passed from the platform to dart.
  static const errnoGeneral = 1;
  static const errnoUnsupportedCodec = 2;

I have found a way to pass static constants through the api which avoid having to maintain mappings in the host code.

This is still fairly ugly but provides a work around until static consts are supported.

When creating an argument class:

class StartCar
{
int carId;
int mode;
int const_suv_mode;
int const_sports_mode;
}

You then need another 'helper' class.
class StartCardConsts
{
static const suv_mode = 1;
static const sports_mode = 2;
}

When constructing the argument class:

var args = StartCar();
args.carId = xx;
args.mode = StartCardConsts.suv_mode;
args.const_suv_mode = StartCardConsts.suv_mode;
args.const_sports_mode = StartCardConsts.sports_mode;

HostApi().startCar(args);

The resulting java/ios code will now have getters for each of the modes so you can write

if (args.mode == args.getConstSuvMode())

closed as fixed by flutter/packages#12032

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

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[pigeon] Support static constant values #66518

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[pigeon] Support static constant values #66518

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bsutton commented on Sep 24, 2020

bsutton commented on Oct 5, 2020

serverplumber commented on Aug 26, 2022

kfieldi5 commented on Apr 6, 2024

tarrinneal commented on Jul 21, 2026

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