# Pluto --- Function barrier
**URL:** https://discourse.julialang.org/t/pluto-function-barrier/59736
**Category:** Tooling
**Tags:** pluto
**Created:** [April 21, 2021, 1:18pm UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736 "2021-04-21T13:18:51Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Tomas\_Pevny](https://discourse.julialang.org/u/Tomas_Pevny)
#### Post date: [April 21, 2021, 1:18pm UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736/1 "2021-04-21T13:18:51Z")
Dear all,
I am sure that this was here solved / asked before, but i have not found the answer.
I am playing with the idea of implementing a visual frontend for Mill / JsonGrinder, which will allow you to upload the training data, tweak a model, and then let you start training. I would like to delay a training, such that it will start after all the stuff like models is finished. Thus, I need something like a barrier. I wanted to implement it using a “Button”, where I would have a start button and the training will start if I change the button. But this does not work, because I cannot assign the value to the variable bind to the button.
Something like:
Cell defining button
```julia
md"""
$(@bind go Button("Train!"))
"""
```
Cell performing training
```julia
if go == "Train!"
Flux.Optimise.train!((x,y) -> loss(model, x, y), ps, repeatedly(minibatch, iterations), opt)
go = "finished"
end
```
Does anyone has an idea, how can I achieve this?
Thanks for an answer in advance.
---
### Author:  [@stillyslalom](https://discourse.julialang.org/u/stillyslalom)
#### Post date: [April 21, 2021, 2:43pm UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736/2 "2021-04-21T14:43:46Z")
I prefer to use `CheckBox` for execution barriers - it’s a better fit for Pluto’s reactivity model.
```julia
md"""
Train! $(@bind cb CheckBox())
"""
```
```julia
if cb
"go!"
end
```
---
### Author:  [@lungben](https://discourse.julialang.org/u/lungben)
#### Post date: [April 21, 2021, 4:41pm UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736/3 "2021-04-21T16:41:48Z")
The functionality to delay execution of specific cells (and their dependencies) will be available in Pluto itself soon - you can try it out here (GUI not final, but should be fully operational):
>
>
> My first works on #298
>
> Still very WIP!
>
> Use Cases:
>
> \- give a method to p…revent auto-update of cells which take too long to compute to keep the notebook reactive and/or save computational resources.
> \- step-by-step computations for educational purposes
>
> Suggestion:
>
> \- Allow the users to add execution barriers to Pluto cells from inside Pluto.
> \- These barriers block execution of the cell they are added to (i.e. located before the cell) if active.
> \- The barriers should be stored in the notebook.jl file, e.g. as comments.
> \- If the notebook.jl file is executed in Julia (without Pluto), the whole file should run, ignoring execution barriers (there would be no way to turn them off without Pluto anyhow).
> \- If an execution barrier is active, the cell and all cells depending on this cell should be marked gray in Pluto, so that it is obvious that they are not executed.
> \- When deactivating an execution barrier, the corresponding cell and all dependent cells are executed immediately and not grayed out anymore.
>
> Technical implementation:
>
> \- \[x\] Execution barrier information (is there a barrier? is it active?) could be added to the Cell structs in the backend.
> \- \[x\] Save this information in notebook.jl files and load it from there
> \- \[x\] Based on which cells are deactivated and the cell dependency information, the backend decides which cells to evaluate in case of changes.
> \- \[x\] Pass the barrier information to the frontend
> \- \[x\] In the frontend, the information whether a cell is grayed out is determined based on the execution barrier information in the Cells and the cell dependency information from #891
> \- \[x\] Frontend functionality for activating and deactivating of execution barriers plus visualization of execution barrirers required.
> \- \[x\] Pass changes in barrier information back to the backend
> \- \[x\] Run cell if its execution barrier is deactivated and it does not depend on any activated barrier
> \- \[x\] Tests?
> \- \[x\] Merge current master (currently not working for me out-of-the-box)
>
> Note: this PR is based on #891, the first commit specific to this PR is 5975d25.
>
>
> \# Try it out!
>
> \`\`\`julia
> julia\> \]
> pkg\> activate --temp
> pkg\> add https://github.com/lungben/Pluto.jl#execution\_barrier
> julia\> import Pluto; Pluto.run()
> \`\`\`
For usage, you could take a look at my PlutoCon talk:
[ ](https://www.youtube.com/watch?v=UJRRauTR9Qg)
---
### Author:  [@Tomas\_Pevny](https://discourse.julialang.org/u/Tomas_Pevny)
#### Post date: [April 21, 2021, 4:53pm UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736/4 "2021-04-21T16:53:19Z")
I was watching your talk and I was thinking about the solution. The checkbox is a neat idea. Thanks a lot.
---
### Author:  [@ThummeTo](https://discourse.julialang.org/u/ThummeTo)
#### Post date: [June 17, 2024, 2:26pm UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736/5 "2024-06-17T14:26:32Z")
Three years later 🙂
I also use the checkbox-way, the main problem is that the checkbox stays activated after enabling it. So in the example by @Tomas_Pevny the training would start as soon as I check “Train”, but if I change some reactive cells above the “Train” checkbox, a training is triggered for every GUI action.
The intended behavior would be: Check the checkbox, start a single training while also deactivating the checkbox (to prevent triggering many trainings). Is this possible?
Or is there a better way to solve this now?
Thanks!
---
### Author:  [@werpers](https://discourse.julialang.org/u/werpers)
#### Post date: [June 18, 2024, 7:43am UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736/6 "2024-06-18T07:43:41Z")
While trying to solve a similar problem I found this thread: [PlutoUI: Trigger long computation only after user sets many parameters and confirms](https://discourse.julialang.org/t/plutoui-trigger-long-computation-only-after-user-sets-many-parameters-and-confirms/112475)
I liked the following:
(each code block a Pluto cell)
```Julia
using PlutoUI
```
```Julia
parameters = (1,2,3)
```
```Julia
parameters; @bind trigger CheckBox(default=false)
```
```Julia
result = trigger ? sum(parameters) : nothing
```
This setup means that every time you change `parameters` the check box will be recreated unchecked, blocking the computation.
---
### Author:  [@ThummeTo](https://discourse.julialang.org/u/ThummeTo)
#### Post date: [June 18, 2024, 8:12am UTC](https://discourse.julialang.org/t/pluto-function-barrier/59736/7 "2024-06-18T08:12:54Z")
Ahh, I see! Nice one!
Thanks!
EDIT: Should be marked as solution IMO.