GTL Variable Reference

Variables are qualified values enclosed in % characters and optionally preceded by formatting options. At evaluation-time, they are substituted by their corresponding value in the active translation scope.

A variable can be of the following types:

For example, the variable %Name% of an interface can be directly evaluated by a macro and replaced by the name of the interface in the generated file.

%[.formatting-options:]variable%

[outer-scope.][variable-object.][object-scope.]object-member
[outer-scope.][variable-object.][collection-scope.]collection-member
[outer-scope.]local-variable
[outer-scope.]global-variable

volatile-attribute
property
[target-code::]extended-attribute
[target-code::][metaclass-name::]template-name[(parameter-list)]
[*]+local-value[(parameter-list)]

objecttype-property
oid-valued-object-member
this

First
IsEmpty
Count

First

local-object
[*]local-value

global-object
global-value
$environment variable

global-object
local-object

[outer-scope.]Outer

[object-scope.]object-member-object
collection-scope.collection-member-object

[object-scope.]collection
[object-scope.]semi-colon-terminated-oid-valued object-member

• Object Members
  An object member can be a standard property, an extended attribute, a template or a volatile attribute. There can be three types of standard property: boolean, string or object. The value of a standard property can be:
• Collection Members
  Each object can have one or more collections, which contain objects with which it interacts. For example, a table has collections of columns, indexes, business rules and so on.
• Conditional Blocks
  Conditional blocks can be used to specify different templates based on the value of a variable. Two different forms are available:
• Global Variables
  Global variables are available regardless of the current scope. A number of GTL-specific variables are defined as global as listed in the following table:
• Local Variables
  You can define local variables with the .set_object and .set_value macros
• Formatting Options
  You can change the formatting of variables by embedding formatting options in variable syntax as follows:
• GTL Operators
  GTL supports standard arithmetic operators along with some advanced template operators.
• Translation Scope
  The translation scope defines the context for evaluating a template, by determining the object to which the template is applied. The scope can change during the translation of a template, but only one object is active at any given time.
• Inheritance and Polymorphism
  Templates are defined with respect to a given metaclass and are inherited by and available to the children of the metaclass. In the following example, the definition template defined on the parent metaclass is available to, and used in the evaluation of the content template on the child metaclass.
• Shortcut Translation
  Shortcuts are dereferenced during translation: the scope of the target object replaces the scope of the shortcut.
• Escape Sequences
  Escape sequences are specific characters sequences used for layout of the generated file output.
• Sharing Templates
  In the GTL mechanism you can share conditions, templates and sub-templates to ease object language maintenance and readability.
• Using New Lines in Head and Tail String
  The head and tail string are only generated when necessary. If no code is generated, the head and tail strings do not appear. This can be useful when controlling new lines.
• Using Parameter Passing
  You can pass in, out or in/out parameters to a template through local variables by taking advantage of nested translation scopes. You can access parameters with the %@<number>% variable.
• Error Messages
  Error messages stop the generation of the file in which errors have been found, these errors are displayed in the Preview tab of the corresponding object property sheet.