Adding C Blocks

Let's add this C block:

The block specification

In Specs.as, add the block to the commands array:

src/Specs.as

// control - sprite
["run %n% of the time",					"c", 6, "runPercentOfTheTime",  50],

// ...

// control - stage
["run %n% of the time",					"c", 106, "runPercentOfTheTime",  50],

You will notice the block type is c.

The block implementation

Unlike normal blocks, which are implemented in the primitives directory, C blocks need to be implemented in the Interpreter.as. This is due to their need to access functions that aren't available outside the interpreter. Locate the rest of the primitives and add this:

src/interpreter/Interpreter.as

private function primRunSometimes(b:Block):void {
    if (b.subStack1 == null) return;
    if (Math.random() >= numarg(b, 0)) return;
    startCmdList(b.subStack1);
}

And, don't forget to add it to the primTable, which is located in a function called initPrims.

src/interpreter/Interpreter.as

primTable["runPercentOfTheTime"] = primRunSometimes;

Completed Files

note

These files contain source code from the Your First Scratch Mod tutorial series.

File	Download
src/Specs.as	Specs.as
src/interpreter/Interpreter.as	Interpreter.as