Hi,
Thanks for the response. Seems I have to rethink some habits with Golang.
I'm now using an approach that uses an interface:
type MessageHandler interface {
CanHandle(msg tea.Msg) bool
}
The more general update function now asks whether a sub-model supports a
certain message:
type model struct {
systemStats systemstat.Model
}
if m.systemStats.CanHandle(msg) {
resourceModel, cmd := m.resources.Update(msg)
m.resources = resourceModel.(systemstat.Model)
return m, cmd
} else {
A specific model then is responsible for deciding whether a message is
relevant for it:
func (m Model) CanHandle(msg tea.Msg) bool {
_, isUsageUpdateMsg := msg.(UsageUpdateMsg)
_, isFanUpdateMsg := msg.(FanUpdateMsg)
_, isGpuUpdateMsg := msg.(GpuUpdateMsg)
_, isFrameMsg := msg.(progress.FrameMsg)
return isUsageUpdateMsg || isFanUpdateMsg || isGpuUpdateMsg || isFrameMsg
}
Feels better than the previous solutions.
Will Faught schrieb am Sonntag, 23. November 2025 um 21:50:45 UTC+1:
> > Is this possible in Go? To have a "wildcard" type parameter? If not,
> what would be an alternative to the above?
>
> I don’t believe so. That would require pattern matching on constructors,
> which Go doesn’t have.
>
> It seems to me you can either assign msg to a non-generic interface and
> then type-switch over non-generic type possibilities, or invoke methods on
> msg that implement the type switch cases.
>
> In my opinion, parametrically-polymorphic (generic) code is supposed to
> behave the same regardless of the instantiated type, so you’re probably
> heading off into the weeds with this approach. If you want code to behave
> differently based on the concrete type (ad-hoc polymorphism), that’s what
> interfaces are for. Don’t mix the two in the same place.
>
> Will
>
> On Nov 23, 2025, at 4:09 AM, Matthias Jeschke <[email protected]> wrote:
>
> Hi,
>
> I'm experimenting with bubbletea for creating a TUI and I came across the
> following problem:
>
> I have a generic struct declared:
>
> type ResourceUpdateMsg[T any] struct {
> value T
> }
>
> This is used to create messages, e.g.:
>
> func updateCpuStats() tea.Msg {
> cpuStats, _ := cpu.Percent(0, false)
> return ResourceUpdateMsg[Cpu]{
> Cpu{
> Usage: cpuStats[0],
> },
> }
> }
>
> Now, in one update function I'm not interested in the specific type of a
> message; each message should be routed to another, more specific update
> function:
>
> switch msg := msg.(type) {
>
> case resources.ResourceUpdateMsg[any]:
> resourceModel, cmd := m.resources.Update(msg)
> m.resources = resourceModel.(resources.Model)
> return m, cmd
> ....
> }
>
> In the other, specific update function the switch distinguishes between
> different types:
>
> switch msg := msg.(type) {
> case ResourceUpdateMsg[Cpu]:
> m.Cpu = msg.value
> cmd := m.Progress.CpuProgress.SetPercent(m.Cpu.Usage / 100)
> return m, tea.Batch(tickCmd(updateCpuStats), cmd)
> case ResourceUpdateMsg[Mem]:
> m.Mem = msg.value
> cmd := m.Progress.MemProgress.SetPercent(m.Mem.Usage / 100)
> return m, tea.Batch(tickCmd(updateMemoryStats), cmd)
> ...
> }
>
> But this does not work, the case is never selected in the first update
> function. I have to write all cases, but each case basically does the same:
> route the message to the other function.
>
> I'm fairly new to Go and my background is Java / Kotlin. In those
> languages I would work with inheritance.
>
> Is this possible in Go? To have a "wildcard" type parameter? If not, what
> would be an alternative to the above?
>
>
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>
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