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[GH-ISSUE #732] Why SetFocus returns Application? #537

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opened 2026-03-04 01:05:50 +03:00 by kerem · 8 comments

kerem commented

2026-03-04 01:05:50 +03:00

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Originally created by @abitrolly on GitHub (Jun 5, 2022).
Original GitHub issue: https://github.com/rivo/tview/issues/732

github.com/rivo/tview@9994674d60/application.go (L705)

It doesn't seem logical to return Application. What is it for?

Originally created by @abitrolly on GitHub (Jun 5, 2022). Original GitHub issue: https://github.com/rivo/tview/issues/732 https://github.com/rivo/tview/blob/9994674d60a85d2c18e2192ef58195fff743091f/application.go#L705 It doesn't seem logical to return Application. What is it for?

kerem closed this issue

2026-03-04 01:05:50 +03:00

kerem commented

2026-03-04 01:05:51 +03:00

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@moson-mo commented on GitHub (Jun 6, 2022):

So that you can chain several method calls. Most of the methods do this in this library.

Example (lines 10 to 17):
https://github.com/rivo/tview/blob/master/demos/form/main.go

@moson-mo commented on GitHub (Jun 6, 2022): So that you can chain several method calls. Most of the methods do this in this library. Example (lines 10 to 17): https://github.com/rivo/tview/blob/master/demos/form/main.go

kerem commented

2026-03-04 01:05:51 +03:00

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@abitrolly commented on GitHub (Jun 6, 2022):

Yea, well, but I could not find where SetFocus is used this way.

github.com/rivo/tview@9994674d60/demos/form/main.go (L10-L17)

@abitrolly commented on GitHub (Jun 6, 2022): Yea, well, but I could not find where `SetFocus` is used this way. https://github.com/rivo/tview/blob/9994674d60a85d2c18e2192ef58195fff743091f/demos/form/main.go#L10-L17

kerem commented

2026-03-04 01:05:51 +03:00

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@moson-mo commented on GitHub (Jun 6, 2022):

Yea, well, but I could not find where SetFocus is used this way.

Well, it probably isn't in any of the examples. If you'd need to, you could though.
Nobody forces you to use the return value of that method... 🤷 😉

@moson-mo commented on GitHub (Jun 6, 2022): > Yea, well, but I could not find where `SetFocus` is used this way. Well, it probably isn't in any of the examples. If you'd need to, you could though. Nobody forces you to use the return value of that method... :shrug: :wink:

kerem commented

2026-03-04 01:05:51 +03:00

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@abitrolly commented on GitHub (Jun 6, 2022):

SetFocus should be passed to input handlers.

github.com/rivo/tview@9994674d60/frame.go (L172)

So I wonder if it is some kind of hack to pass application pointer to widgets that otherwise do not know where the application is?

@abitrolly commented on GitHub (Jun 6, 2022): `SetFocus` should be passed to input handlers. https://github.com/rivo/tview/blob/9994674d60a85d2c18e2192ef58195fff743091f/frame.go#L172 So I wonder if it is some kind of hack to pass application pointer to widgets that otherwise do not know where the application is?

kerem commented

2026-03-04 01:05:51 +03:00

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@rivo commented on GitHub (Nov 12, 2022):

The hierarchy is top-down. Application knows about other primitives but primitives don't know Application directly. They get what they need, when they need it (like here, a setFocus function), but otherwise they don't need a reference to the Application object.

@rivo commented on GitHub (Nov 12, 2022): The hierarchy is top-down. `Application` knows about other primitives but primitives don't know `Application` directly. They get what they need, when they need it (like here, a `setFocus` function), but otherwise they don't need a reference to the `Application` object.

kerem commented

2026-03-04 01:05:51 +03:00

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@abitrolly commented on GitHub (Nov 12, 2022):

Is there a way for primitive to directly receive the Application handler?

Like if I want to pass focus to the previous element in UI, and I don't know which element it was, I could potentially use Application to find out.

@abitrolly commented on GitHub (Nov 12, 2022): Is there a way for primitive to directly receive the `Application` handler? Like if I want to pass focus to the previous element in UI, and I don't know which element it was, I could potentially use `Application` to find out.

kerem commented

2026-03-04 01:05:51 +03:00

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@rivo commented on GitHub (Nov 13, 2022):

Not as part of the tview library. Most users will probably keep a package-global reference somewhere in their application.

@rivo commented on GitHub (Nov 13, 2022): Not as part of the `tview` library. Most users will probably keep a package-global reference somewhere in their application.

kerem commented

2026-03-04 01:05:51 +03:00

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@abitrolly commented on GitHub (Nov 13, 2022):

Fair enough. So SetFocus returns Application so that the call can be chained with other methods. Not for passing Application around. Thanks for the explanations.

@abitrolly commented on GitHub (Nov 13, 2022): Fair enough. So `SetFocus` returns `Application` so that the call can be chained with other methods. Not for passing `Application` around. Thanks for the explanations.