A global block can declare properties, just as they could be defined in a class. The difference is that the global property does not need a class instance: there is only one instance of this property. Other than that, a global property behaves like a class property. The read/write specifiers for the global property must also be regular procedures, not methods.
The concept of a global property is specific to Free Pascal, and does not exist in Delphi. ObjFPC mode is required to work with properties.
The concept of a global property can be used to “hide” the location of the value, or to calculate the value on the fly, or to check the values which are written to the property.
The declaration is as follows:
The following is an example:
The read/write specifiers can be hidden by declaring them in another unit which must be in the uses clause of the unit. This can be used to hide the read/write access specifiers for programmers, just as if they were in a private section of a class (discussed below). For the previous example, this could look as follows:
The unit testprop would then look like:
More information about properties can be found in chapter 6, page 288.