I made the `all at once` block actually run all at once. My code shouldn't work, I'd like to know why it does anyway...

Wowfunhappy

Scratch has an “all at once” C-shaped block. https://scratch.mit.edu/projects/788226048. It doesn't do much of anything, and is hidden in the block palette. The source code in scratch-vm provides a pretty good description of why it exists:

https://github.com/LLK/scratch-vm/blob/f2781d3ea50d17e5088eec413935fd639cf3995b/src/blocks/scratch3_control.js#L195

allAtOnce (args, util) {
    // Since the "all at once" block is implemented for compatiblity with
    // Scratch 2.0 projects, it behaves the same way it did in 2.0, which
    // is to simply run the contained script (like "if 1 = 1").
    // (In early versions of Scratch 2.0, it would work the same way as
    // "run without screen refresh" custom blocks do now, but this was
    // removed before the release of 2.0.)
    util.startBranch(1, false);
}

I wanted to make the `all at once` block behave as it did in those early versions of Scratch 2.0, when the contained script would run without screen refresh.

I decided to try:

allAtOnce (args, util) {
    util.thread.peekStackFrame().warpMode = true;
    util.startBranch(1, false);
    util.thread.peekStackFrame().warpMode = false;
}

The results were… interesting.

I had effectively created the anti-all-at-once block: code outside this block was running all at once, while code inside the block ran normally! It was almost as if I had turned warp mode off at the start and on at the end…

…on a hunch, I decided to try doing just that:

allAtOnce (args, util) {
    util.thread.peekStackFrame().warpMode = false;
    util.startBranch(1, false);
    util.thread.peekStackFrame().warpMode = true;
}

This version seems to work perfectly! Code inside the all at once block runs without screen refresh, while code outside the block is unaffected!

This is great, but I'm totally weirded out! Clearly, I don't really understand what this code is doing, and I'm concerned that could lead to unintended side effects down the road.

Does anyone know why Scratch is seemingly executing this function bottom-to-top?

Last edited by Wowfunhappy (Jan. 14, 2023 16:41:52)

CST1229

Scratch executes all block functions (that don't return a Promise) all at once (ha) - util.startBranch() doesn't execute the branch right when it is executed, it essentially schedules the branch to start after the function finishes running.

I don't know why that works - it seems like that would make the entire script run without screen refresh (including the blocks after it), or run the script INSIDE the c-slot with screen refresh and run the blocks after it WITHOUT screen refresh…

When I also did this, I handled it by adding an additional argument to the startBranch() function, which passes it to the sequencer's stepBranch() function (via another added argument), which passes it to the thread's pushStack() function (via ANOTHER added argument), which then finally passes the warp mode to the created stack frame.

Last edited by CST1229 (Feb. 3, 2023 18:11:27)

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Wowfunhappy

CST1229 wrote:
Scratch executes all block functions (that don't return a Promise) all at once (ha) - util.startBranch() doesn't execute the branch right when it is executed, it essentially schedules the branch to start after the function finishes running.

I don't know why that works - it seems like that would make the entire script run without screen refresh (including the blocks after it), or run the script INSIDE the c-slot with screen refresh and run the blocks after it WITHOUT screen refresh…

When I also did this, I handled it by adding an additional argument to the startBranch() function, which passes it to the sequencer's stepBranch() function (via another added argument), which passes it to the thread's pushStack() function (via ANOTHER added argument), which then finally passes the warp mode to the created stack frame.

Thank you!

rdococ

If `startBranch()` pushes another frame to the stack to represent the code in the C block, then the second call to `peekStackFrame()` returns the new stack frame and you're only setting that frame to warp.

Last edited by rdococ (April 14, 2023 18:37:25)

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imakegameslol88888

because you coded it properly

I respectfully don't know that my forum is a duplicate. The duplicate is probably too old for me to see

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dynamicsofscratch

deleted becuase my lemon brain just realized that I messed up the entire point of what you we're asking…

Last edited by dynamicsofscratch (April 22, 2023 05:43:05)

aII toasters toast toast, but what happens when there are no longer toasters being produced? will their technology simply become obsolete, with humans moving onto bigger, better things? will toast become a distant memory, written in textbooks of the future as foods us simpler generations ate? who's to say! society is constantly moving, changing, evolving, ideas being built upon, improved upon, theories being proven or disproven. are we but a blip on the timeline? sure, our names may not be remembered, but that's not the point. you can make a change. you can make a difference. you can make the world better, even if you don't know yet. and the first step is to go for it. even if you are afraid of failure. going back to the example of toasters, do you know off the top of your head who invented them? no? have you used one? probably. so, even if you don't remember my name, if I was able to help awnser your question, that is enough. if I was able to help you, even in the slightest way, this could push you to continue with scratch and not give up after the program crashes, and maybe one day learn other programming languages and change the world. everything is a cause and effect reaction, new inventions lead to the technology of the future, and even as the generations of the past are slowly forgotten, their influence lives on to this day, affecting how the world eventually turned out and how it will be for generations to come.

and, without toasters, we wouldn't have toast.

Regards
dynamicsofscratch

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Wowfunhappy

rdococ wrote:
If `startBranch()` pushes another frame to the stack to represent the code in the C block, then the second call to `peekStackFrame()` returns the new stack frame and you're only setting that frame to warp.

I'll admit I had to re-read this many times before I understood it, but—thank you! Combined with what @CST1229 said above about the branch not starting immediately, now the behavior makes complete sense!

julianlukasiak

Make IT as turbowarp extension.

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Mr_rudy

julianlukasiak wrote:
Make IT as turbowarp extension.

that isn't possible, it is a block in the VM, if you want to use it in turbowarp just use custom blocks

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BigNate469

Or you could just find a project that contains the block, download it, upload it to turbowarp, delete everything but the block in question, and you now should be able to use it in turbowarp, just copy and paste the block as necessary.

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