Difference between revisions of "Class Structure Hash"
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| − | '''Purpose:''' | + | '''Purpose:''' |
A request for comments on the notion of various equality tests for a class. The tests can be used in areas such as serialization, proxy/stub calls, versioning, dynamic type loading, etc. | A request for comments on the notion of various equality tests for a class. The tests can be used in areas such as serialization, proxy/stub calls, versioning, dynamic type loading, etc. | ||
Hash value are a SHA256 hash | Hash value are a SHA256 hash | ||
| − | '''Class-text hash:''' | + | '''Class-text hash:''' |
* Complete hash of the text of the class. Any change including non-processed areas such as `note' or comments would cause the hash value to change. | * Complete hash of the text of the class. Any change including non-processed areas such as `note' or comments would cause the hash value to change. | ||
| − | '''Semantic-text hash:''' | + | '''Semantic-text hash:''' |
* Hash value of the semantically-meaningful text of the class. This would ignore the actual character contents of breaks and would ignore comments and note fields. If a buggy version of a class is discovered, it could be rejected for serialization or connection by this hash value. | * Hash value of the semantically-meaningful text of the class. This would ignore the actual character contents of breaks and would ignore comments and note fields. If a buggy version of a class is discovered, it could be rejected for serialization or connection by this hash value. | ||
| − | '''Attribute hash:''' | + | '''Attribute hash:''' |
* Hash value of the attributes of the class. This would essentially mean anything with an equal attribute hash could be deserialized/serialized without recovery. | * Hash value of the attributes of the class. This would essentially mean anything with an equal attribute hash could be deserialized/serialized without recovery. | ||
| − | '''Feature hash:''' | + | '''Feature hash:''' |
* Name, signature, and export hash for a feature | * Name, signature, and export hash for a feature | ||
| − | '''Interface-to-class hash:''' | + | '''Interface-to-class hash:''' |
* Hash value of feature names and signature exported to a specific class. This would be useful for remote proxying. A class would have a additional value for each class to which features are exported. If class A exports features to {ANY}, {A}, {B}, and {NONE} it would have a hash value for each to say whether the interface exported to either ANY, A, or B has changed. Changes to features exported to A would affect the hash code for {ANY} and {A} but not {B}. Changes to features exported to NONE would not affect any hash values. | * Hash value of feature names and signature exported to a specific class. This would be useful for remote proxying. A class would have a additional value for each class to which features are exported. If class A exports features to {ANY}, {A}, {B}, and {NONE} it would have a hash value for each to say whether the interface exported to either ANY, A, or B has changed. Changes to features exported to A would affect the hash code for {ANY} and {A} but not {B}. Changes to features exported to NONE would not affect any hash values. | ||
| − | '''Contract hash:''' | + | '''Contract hash:''' |
* A hash value for a the contract of a feature. | * A hash value for a the contract of a feature. | ||
| − | '''Interface-to-class contract hash:''' | + | '''Interface-to-class contract hash:''' |
* A hash value for the contract of all features exported to a class. | * A hash value for the contract of all features exported to a class. | ||
| − | '''Additional issues:''' | + | '''Additional issues:''' |
| − | * Mutual recursive references. In some cases two classes reference each other; this could lead to difficulty in creating a hash value for both. | + | * Mutual recursive references. In some cases two classes reference each other; this could lead to difficulty in creating a hash value for both. |
| − | * Some traditionally non-semantic areas such as `note' actually have semantic value. | + | * Some traditionally non-semantic areas such as `note' actually have semantic value. |
* Are 256 bits needed? Maybe truncate hash to 128 bits or 64 bits. | * Are 256 bits needed? Maybe truncate hash to 128 bits or 64 bits. | ||
Latest revision as of 18:55, 7 March 2010
Purpose: A request for comments on the notion of various equality tests for a class. The tests can be used in areas such as serialization, proxy/stub calls, versioning, dynamic type loading, etc.
Hash value are a SHA256 hash
Class-text hash:
- Complete hash of the text of the class. Any change including non-processed areas such as `note' or comments would cause the hash value to change.
Semantic-text hash:
- Hash value of the semantically-meaningful text of the class. This would ignore the actual character contents of breaks and would ignore comments and note fields. If a buggy version of a class is discovered, it could be rejected for serialization or connection by this hash value.
Attribute hash:
- Hash value of the attributes of the class. This would essentially mean anything with an equal attribute hash could be deserialized/serialized without recovery.
Feature hash:
- Name, signature, and export hash for a feature
Interface-to-class hash:
- Hash value of feature names and signature exported to a specific class. This would be useful for remote proxying. A class would have a additional value for each class to which features are exported. If class A exports features to {ANY}, {A}, {B}, and {NONE} it would have a hash value for each to say whether the interface exported to either ANY, A, or B has changed. Changes to features exported to A would affect the hash code for {ANY} and {A} but not {B}. Changes to features exported to NONE would not affect any hash values.
Contract hash:
- A hash value for a the contract of a feature.
Interface-to-class contract hash:
- A hash value for the contract of all features exported to a class.
Additional issues:
- Mutual recursive references. In some cases two classes reference each other; this could lead to difficulty in creating a hash value for both.
- Some traditionally non-semantic areas such as `note' actually have semantic value.
- Are 256 bits needed? Maybe truncate hash to 128 bits or 64 bits.
