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Procedures, also called functions or methods, are a tool in many programming languages, which allow common blocks of code to be grouped and called by a single name. Blocks in Scratch are procedures themselves, as they are blocks of compiled code executed all at once. Procedures have inputs or arguments, which are used to edit the procedure's effect slightly. For example, the "move (10) steps" block has the numerical argument (the bracketed bit) which specifies the distance to be moved: 10 pixels in this case.

Procedures in Scratch

A "jump" procedure — Scratch pre-alpha at Scratch Day 2011.
A "jump" procedure with an argument — Scratch pre-alpha at Scratch Day 2011.
Recursive factorial procedure — Scratch 2.0 alpha.

Procedures will be added in Scratch 2.0.[1] There will be a "More Blocks" palette, where procedures in the project are stored.[2] This palette also houses a "make a block" button, similar to the "make a variable/list" buttons in Data Blocks. The procedures will be local to each sprite.[3] Procedures in Scratch 2.0 will only be Stack Blocks, not Reporter or Boolean block styles, and will support recursion. Procedures will take arguments of all three block types. Reporter or boolean procedures will not be available in Scratch 2.0, but may be in future versions.[4]

Procedures in BYOB/Snap!

Snap!, previously called BYOB (Build Your Own Blocks), is a Scratch modification that allows procedures. Snap!'s procedures allow all 3 types of blocks, with arguments, and also recursion.

Procedures in Squeak

Main article: Squeak Tutorial#Methods

Procedures in Squeak are called methods.

References

  1. http://blog.scratch.mit.edu/2011/03/scratch-20-progress-report-create-your.html
  2. http://blog.scratch.mit.edu/2012/02/scratch-20-project-page-and-project.html
  3. http://scratch.mit.edu/forums/viewtopic.php?pid=719181#p719181
  4. http://scratched.media.mit.edu/discussions/scratch-20/custom-block-types