Scratch

here are some other things you should add:

ifTrue  -   if the variable it procedes is true (usually the variable representing a boolean) it does/reports what follows it. Used like this:

variable = 10 ifTrue: [^ 'the variable is 10']

Add CYOB inputters ($String$)


And loops, like whileTrue:

whileTrue - Repeats while true.

[t1 = 3] whileTrue: [t2 _ t2 + 1]

Maybe a complete list of all the block types and input types.

nXIII wrote:

johnnydean1 wrote:

Done the first bit already but here:

Guide Continued
In squeak you can also use special statments, such as whileTrue: or ifTrue: use them as shown.

[t1 = 3] whileTrue:
[
code
].

t1 = 4
ifTrue: [
code
]
ifFalse: [
code
].

Also

t3 timesRepeat: [
code
].

will repeat the code the value of t3 number of times.

Those aren't special statements, they're just messages received by Boolean objects. (or blocks or numbers)

Well there not basic code either. but are the square brackets needed?

markyparky56 wrote:

nXIII wrote:

johnnydean1 wrote:

Done the first bit already but here:

Guide Continued
In squeak you can also use special statments, such as whileTrue: or ifTrue: use them as shown.

[t1 = 3] whileTrue:
[
code
].

t1 = 4
ifTrue: [
code
]
ifFalse: [
code
].

Also

t3 timesRepeat: [
code
].

will repeat the code the value of t3 number of times.

Those aren't special statements, they're just messages received by Boolean objects. (or blocks or numbers)

Well there not basic code either. but are the square brackets needed?

The brackets indicate blocks. See my thread for info on blocks.

yep

This may be in the wrong spot, so sorry.

What does nil mean? 

Last edited by bbbeb (2010-07-04 22:32:43)

It means the variable has not been set generaly.

Also means 0

Thanks! I have known about the sorce code but I have never learned how to make blocks of my very own self. Thanks again!

johnnydean1 wrote:

I am hoping that this will help people, it took me a while...

Maybe some more stuff like examples on how to do certin things which can be added/adapt to work.

johnnydean1 wrote:

yep

I'm not really sure what you meant here. I'll explain.

markyparky56 wrote:

nXIII wrote:

markyparky56 wrote:

Well there not basic code either. but are the square brackets needed?

The brackets indicate blocks. See my thread for info on blocks.

As in places to put code?

As in unevaluated code. For example,

sandwich := [:bread :toppings | {'Bread: ', bread asString. 'Toppings: ', toppings asArray asString}].

This tells me how to make a sandwich (array with two strings, "Bread: bread_type" and "Toppings: toppings") with just the toppings and bread given. I can do this as many times as I want with whatever things I want by simply typing

sandwich value: 'bread' value: #(topping topping topping).
"or even"
sandwich value: self basicsize asString, ' different kinds!' value: {self. self class}.

However, to simply put

bread := 'Wheat'.
toppings := #(cheese lettuce tomato).
sandwich := {'Bread: ', bread. 'Toppings: ', toppings}.

would only give me one sandwich, and I wouldn't know how to make another one of a different type without doing all that again manually.

Last edited by nXIII (2010-07-06 18:32:08)

Jwosty wrote:

jonnydean1 wrote:

Scratch stores inputs such as %n as
t1

Actually, the temporary variables (such as t1) only appear as t1, t2, t3 etc. in the decompiled image. for example, here is the decompiled version of the costume index method (The one you would find in 'scratch.image'):

Code:

costumeIndex: t1 
    | t2 t3 t4 |
    t2 _ media reject: [:t5 | t5 isSound].
    t2 size = 0 ifTrue: [^ self].
    t3 _ t1 rounded - 1 \\ t2 size + 1.
    t4 _ t2 at: t3.
    costume == t4 ifFalse: [self lookLike: t4 mediaName]

And this is the original (The one you would find in: 'Scratch 1.4 (source code of 23-Sep-09)'):

Code:

costumeIndex: aNumber
    "Set my costume to the costume at the given index modulo my total number of costumes. Costumes are numbered starting at 1."

    | cList i newC |
    cList _ media reject: [:m | m isSound].
    cList size = 0 ifTrue: [^ self].  "should never happen..."
    i _ ((aNumber rounded - 1) \\ cList size) + 1.
    newC _ cList at: i.
    costume == newC ifFalse: [self lookLike: newC mediaName].

These are the same method.

The computer just doesn't care about the comments or the names of the temporary variables ('t1' stands for temporary1).

Scratch actually doesn't "store" the inputs as all, it simply calls the block's selector with the arguments as, well, arguments  . The fact that they are "t1", "t2", etc. is because the method is (I believe) being extracted from the actual method (I forget what the class name is)