Progress
Language Tutorial
for Character
About Blocks
The Progress 4GL is a block-structured language. A block is a series of 4GL statements grouped together and treated as a single unit. Blocks are important because Progress bases many default behaviors on blocks. For example, earlier you learned about the default frame. If you don’t define a frame, Progress creates one for you (the default frame) when you display widgets. Actually, each block in your procedure can have a default frame; default frame behavior is based on blocks.
There are several types of blocks that you can use within your application. They include:
Here are some general statements about blocks, although you’ll learn about some exceptions in the sections that follow:
- A block begins with a block header statement.
- A block ends with the END statement.
- Most block types come with implicitly defined services called block properties. Default frame allocation, for example, is a service, or block property, of many blocks. In the tutorial, you’ll work with these block properties: looping, record reading, and frame allocation.
- Many blocks have syntax options that allow you to define services explicitly, either to override implicit services or to add new services.
- You can name blocks by adding a label and a colon before the block header as shown in the following code:
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