Reasoning With The If Then Blocks

mepomepo

There is no reasoning with scratch, or the If then blocks.
Example of an if then block:

if <> then

end

but here is 3 questions:
what are the if then blocks?
why did the ST make them?
why are they here?

But here is the BIG question:

What in the world is without the if then blocks, and why, why, do they even mostly used?

Last edited by mepomepo (May 29, 2022 05:12:06)

-EmeraldThunder-

The if then blocks are so your code can make decisions based on inputs or other data. If these blocks weren't in scratch, then it would certainly be a lot harder to create code with non-static outputs.

mepomepo

-EmeraldThunder- wrote:
The if then blocks are so your code can make decisions based on inputs or other data. If these blocks weren't in scratch, then it would certainly be a lot harder to create code with non-static outputs.

Well, sometimes they are compared with the wait until blocks.
ex of wait until block:

wait until <>

-EmeraldThunder-

mepomepo wrote:
(#3)
-EmeraldThunder- wrote:
The if then blocks are so your code can make decisions based on inputs or other data. If these blocks weren't in scratch, then it would certainly be a lot harder to create code with non-static outputs.
Well, sometimes they are compared with the wait until blocks.
ex of wait until block:
wait until <>

Sometimes, the if block can be used in situations the wait until <> block can't.
For example, if you need to evaluate a position of an object in a single frame and then run a script immediately afterwards using a wait until <> block might hang the entire engine on the frame if the position is not correct.
Plus, the wait block has an internal if statement.

const condition = Cast.toBoolean(args.CONDITION);
if (!condition) {
       util.yield();
}

Src: https://github.com/LLK/scratch-vm/blob/develop/src/blocks/scratch3_control.js

Za-Chary

The Scratch Team made the “if then” blocks because they are a basic thing in many other programming languages, including the text-based ones. @-EmeraldThunder- effectively describes what they do.

Here is an example for why “wait until” would not work. Suppose you want to make a character jump by pressing the up arrow key, but only if the space bar is being held down for some reason. Your two options are this:

when [up arrow v] key pressed
if <key [space v] pressed?> then
jump
end

when [up arrow v] key pressed
wait until <key [space v] pressed?>
jump

The first option will have the desired outcome: when the up arrow key is pressed, the character will jump as long as the space key is being held down.

However, the second one doesn't work. If you use the second one, you could press the up arrow key without holding down the space bar, wait 5 minutes while you get a coffee or something, then press the space bar, and the character will jump. This is not the intended behavior.

musicROCKS013

Yes. But remember, if you don’t put anything in the if then block, none of the code in it will run. You have to put one of those “< >” Boolean blocks in it to make it able to run. The if then blocks are arguably the most important block in scratch, although by themselves they are useless.

d_over_dx

bruh this is stupid dont ask

when green flag clicked
forever
if <some condition> then
...
end
end

or will you use:

when green flag clicked
wait until <some condition>
...

and plus this is the main use of the if block.
SCRATCH is to get a SENSE of programming languages, not to make it HARD.

popjam12

d_over_dx wrote:
-snip-

Yep. That's the answer really.

Last edited by popjam12 (May 29, 2022 19:56:17)

d_over_dx

if block in most of the languages i know:
Python:

if condition:
    do_something()

JS (JavaScript):

if condition {
    do_something()
}

d_over_dx

d_over_dx wrote:
if block in most of the languages i know:
Python:
if condition:
    do_something()
JS (JavaScript):
if condition {
    do_something()
}

and, so:
“if” is important. my final statement.

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