Structure of a DCL File

• Format
• The format of a DCL file is plain text. A DCL file describes a tree of tiles and attributes. Tiles may contain a number of sub-tiles or attributes, much like the elements and attributes in an xml document, but with a completely different syntax. The syntax of a dcl file is inspired on C++. A DCL file may contain C++ comments and whitespaces. It also uses curly brackets for nesting content and a semicolon at the end a line.

• Tiles
• A DCL tile can have a name, type and sub-content.
  DCL tiles can be cluster tiles or child tiles. A cluster tile can contain other cluster tiles, child tiles or attributes. A child tile can contain only attributes. The only tile that is not a cluster or a child is default_dcl_settings.
  An example of a child tile is a tile with type "button". A tile with name "my_button" and type "button" could look like this:
my_button : button {//sub-content}
  The name may be omitted:
: button{//sub-content}
  Without subcontent this becomes:
: button{}
  or equivalently:
button;
  An example of a cluster tile is a tile with type "row". A cluster tile with name "my_row" and type "row" could look like this:
my_row : row { my_button : button {//nested sub-content} //sub-content }

• Attributes
• A DCL Attribute is a child of a DCL tile. A DCL Attribute is also always a leaf, meaning that it has no sub-tiles or sub-attributes.
  A DCL attribute is a name-value pair. Its value type can be a "string", a number or a keyword. Some valid keywords are: true, false, horizontal... These are examples of correct attribute syntax:
  label = "textual content"; width = 5.1; alignment = horizontal; my_name = "John Doe";
  An attribute can be predefined or custom. The previous syntax examples label, width, alignment are predefined attributes. The value of predefined attributes influences the looks and the behavior of the dcl dialog to be displayed. A custom attribute like my_name has no predefined meaning but it can be used by a third party program for storage. For more on usage of custom attributes, see get_attr. A string attribute starts and ends with a double quote. To include a double quote character in a string attribute, escape the quote with a backslash. To include a backslash, add a double backslash. label = "a quote: \" a backslash: \\";

• Sample
• This is a sample DCL File:
  my_dialog : dialog { label = "my dialog"; fixed_width = true; height = 55.2; : row { my_button : button { height = 2; label = "my button"; } : edit_box; } ok_cancel; }

• Inheritance
• What we previously called name and type of a tile actually are a derived type and a base type. a : b {//subcontent} means: a inherits from b, with additional subcontent. This is another way in which dcl resembles C++: the colon ':' also denotes inheritance. A base type can either be an atomic type, or a derived type itself, defined elsewhere. Dcl thus allows multilevel inheritance. Derived types can be predefined or user-defined. A predefined derived type is defined in exactly the same way as a user-defined type. In earlier versions predefined types were part of a default dcl file: "base.dcl". This file is builtin in BricsCAD. It is however still possible to add an old "base.dcl" file to the BricsCAD support folder in order to use custom definitions of the predefined types. In the above sample dcl file, the predefined tiles button and edit_box are directly referenced. The tile ok_cancel is an example of a non-atomic predefined tile. It contains an ok and cancel button.