directly from the information stored within the network element's data buffer;
using ``on-the-fly'' access by calling the EMME/2 data bank I/O module whenever a value is needed;
by indirect access to an attribute of another network element via a pointer attribute;
by calling a type specific network element function;
by providing the same constant value for all network elements;
by evaluating an expression based on the other attributes of the same element (see below).
Format: Information on the default formatting of the attribute values, such as field width, decimal precision and alignment.
Protection and validation: Attributes can be declared read-only (e.g. assignment results) or have write permission so that their values may be modified. For writable numerical attributes, the allowed value range may be defined by lower and upper bounds, as well as a default value which is used to initialize newly created elements.
A special data caching mechanism is provided which allows the user to define which attributes should be cached, i.e. stored directly in the data buffer of each network element, instead of reading it on-the-fly from the external data bank whenever needed.
Obtaining an attribute value for a specific network element is done simply by calling the corresponding method of the attribute with the pointer to the network element as argument.
Constant attributes are attributes which are not associated with a particular network element. They can be evaluated for all network element types (or even outside the context of network elements altogether) and will always return the same constant value.
Attributes of the same element type are combined into attribute lists. The network contains one attribute list for the attributes of each element type, and an additional one for constant attributes associated wit
上一页 [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] ... 下一页 >>
特别声明：本站除部分特别声明禁止转载的专稿外的其他文章可以自由转载，但请务必注明出处和原始作者。文章版权归文章原始作者所有。对于被本站转载文章的个人和网站，我们表示深深的谢意。如果本站转载的文章有版权问题请联系编辑人员，我们尽快予以更正。本站所有技术文章、专业软件资料仅供技术人员、高校师生学习交流之用，目的旨在促进与提高中国的交通技术水平；用户获取后不得用于商业目的，否则，所产生的法律责任本站概不负责。
