msdyn365bc - Preprocessor Directives in AL Introduction.

Hi Readers,

Continuing what's new in business central 2020 wave 2.

In this series, we’ll learn about Preprocessor Directives, available directives in AL, and when, why and how why they are used.

As the name justifies, preprocessor directives are a block of statements that gets processed before the actual compilation starts. AL preprocessor directives are the commands for the compiler that affects the compilation process.

#AL, #msdyn365bc

These commands specifies which sections of the code to compile or how to handle specific errors and warnings.

• AL preprocessor directive begins with a # (hash) symbol and all preprocessor directives last for one line. 
• Preprocessor directives are not statements, so they do not end with a semicolon (;).
• Preprocessor directives are terminated by new line rather than semicolon.

In AL, like in other programming languages, preprocessor directives can be used to make code conditional, to suppress warnings, or to enable expand and collapse in code. 

Preprocessor directives can be divided into the following groups. For more information about each type, use the links provided below - 

• Conditional directives
• Regions
• Pragmas

Any code can be made conditional, including table fields, and checked using a conditional directive. 

To check code using a conditional directive, you must define a symbol to check. 

A symbol returns a Boolean value; true or false. 

Symbols can be defined at the beginning of a source file and the scope of the specific symbol is the file that it is defined within. 

You can also define symbols in the app.json file, and then the scope is global for the extension.

This is how a code execute with/without preprocessor directives.

In Next article in this series, we will talk about these directives with examples. 

If you have any questions, add as comments to this article.

Regards,
Saurav Dhyani
www.sauravdhyani.com