DerivedEnumerationTypes < P1076

P1076 Web>VHDLProposals>DerivedEnumerationTypes (2017-04-02, PatrickLehmann) (raw view)EditAttach
---+!! Derived Enumeration Types
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---++!! Proposal Details

| *Authors*        | [[Main.PatrickLehmann][Patrick Lehmann]] |
| *Date Proposed*  | 2017-04-03                               |
| *Last Updated*   | 2017-04-03                               |
| *Focus*          | simulation and synthesis                 |
| *LCS*            | TBD                                      |

---++
%TOC%
---++

---++ Summary
VHDL Libraries and frameworks like PoC or UVVM like to specify a minimum set of enumeration literals for different purposes. The user shall then be
enabled to extend such a basic enumeration type with his own user defined enumeration literals, without using copy and past to create such a list.
It's preferred to find and define a semantic (derived relationship, subtype relationship) between the base and derive type.


---++ Current Situation
Currently, enumeration literals can not be shared between different enumeration types. If a library provider allows a user to create a user defined
enumeration type, then he can only specify the minimum content of such a type by coding guide lines and/or a template.


---++ Requirement
Features:
   * Append literals
   * Implicitly created conversion functions

---++ Use Cases
%GREEN%Add some use cases.%ENDCOLOR%

---++ Implementation details
%GREEN%How is it implemented?%ENDCOLOR%

---++ Code Examples

<pre>
type BaseEnum is (
  STATUS_IDLE,
  STATUS_RESETING,
  STATUS_ERROR
);

type myStatus is new BaseEnum (
  STATUS_READING,
  STATUS_READING_COMPLETE,
  STATUS_WRITING,
  STATUS_WRITING_COMPLETE
);
--type myStatus is new BaseEnum (
--  STATUS_IDLE,
--  STATUS_RESETING,
--  STATUS_ERROR
-- append new literals
--  STATUS_READING,
--  STATUS_READING_COMPLETE,
--  STATUS_WRITING,
--  STATUS_WRITING_COMPLETE
--);
</pre>


---++ Arguments FOR

---++ Arguments AGAINST

---++ General Comments

%COMMENT%

---++ Supporters
   * [[Main.PatrickLehmann][Patrick Lehmann]] - 2017-04-03
   * _Add your signature here to indicate your support for the proposal_

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Topic revision: r1 - 2017-04-02 - 22:25:12 - PatrickLehmann
P1076