Initialization of Explicit References

Explicit references must be initialized before they are used.

Reference Type	must be initialized with
array	array of identical or larger size (a warning is issued in the latter case)
matrix	matrix of identical x size and y size
normal or fixed characteristic line/map	normal or fixed characteristic line/map of kind "variable" and identical dimension (you cannot map a characteristic line to a map or vice versa) type (you cannot map, e.g., a normal characteristic line to a fixed characteristic line) x max size and – for maps – y max size implementation (for implementation experiments) interpolation routine (for ASCET‑SE targets)
normal class (block diagram, ESDL, C code)	another instance of the same class using the same implementation
state machine	another instance of the same state machine using the same implementation
Boolean table	another instance of the same Boolean table using the same implementation
conditional table	another instance of the same conditional table using the same implementation
record	another instance of the same record using the same implementation

To ensure reference initialization, ASCET requires, by default, that the element specified as Reference must be mapped to an element that is not a reference itself. The mapped element must be an element in the same component, and its type must match the reference (see the table above). The scope of the mapped element depends on the scope of the reference:

Local references can be mapped to elements of any scope (local, imported, exported).
Exported references can be mapped to imported or exported elements only.
Imported references cannot be mapped; map the associated exported reference instead.

Note
Explicit references must not be mapped to arrays, matrices or records used as messages. If they are, an error (MMdl3024) is issued during code generation: Cannot use the address of a message object <name>.

Note

Explicit references must not be mapped to arrays, matrices or records used as messages. If they are, an error (MMdl3024) is issued during code generation:

Cannot use the address of a message object <name>.

The mapping is stored with the currently active data set of the component.

In ASCET versions prior to V6.2, the mapping was the only possibility to initialize explicit references. However, to allow customer tool chains to generate data structures and initial values, ASCET V6.2 or higher offers the possibility to generate code for unmapped explicit references. By default, this possibility is deactivated; it can be activated in the context of a project, via the Allow References without Init Valuecode generation option.

Note
If the Allow References without Init Value option is activated, the user is the sole responsible for initialization of references.

If code is generated while Allow References without Init Value is deactivated, an error is issued when an uninitialized reference is found:

GLm3 – Reference init value undefined or not available. Please specify an internal init value for <reference name>.

If code is generated while Allow References without Init Value is activated, a warning is issued if an uninitialized reference is found:

WMdl822 – read access to reference without init value "<reference name>" possibly prior to initialization of reference

By default, this warning is promoted to an error.

In addition, the global analysis, i.e. the analysis of the entire project context, issues an error for an uninitialized reference that is read:

MMdl83 – read access to a definitely uninitialized reference "<reference name>"

Note
The absence of the error does not prove that the reference is always initialized before use. The following list contains three examples for uninitialized references that remain undiscovered. A reference is defined in a multi-instance class, and it is initialized through a reference to that class. aRef and bRef are uninitialized references; aRef = bRef is set in processA, and bRef = aRef is set in processB aRef = (a > b) ? aRef : bRef; with a always larger than b due to intervals, so that this assignment effectively is aRef = aRef

Note

The absence of the error does not prove that the reference is always initialized before use. The Closed following list contains three examples for uninitialized references that remain undiscovered.