principles:liskov_substitution_principle
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principles:liskov_substitution_principle [2020-10-12 16:23] – old revision restored (2013-03-18 09:44) 159.69.186.191 | principles:liskov_substitution_principle [2021-10-18 21:50] – old revision restored (2018-05-27 18:40) christian | ||
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===== Context ===== | ===== Context ===== | ||
/* fill in contexts here: */ | /* fill in contexts here: */ | ||
- | * [[contexts: | + | * [[contexts: |
+ | * [[contexts: | ||
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> " | > " | ||
+ | |||
===== Description ===== | ===== Description ===== | ||
+ | Object-oriented programming languages permit the derivation of subtypes from base types, and subtype polymorphism allows the passing of an object of a subtype where ever an object of the supertype is specified. Suppose '' | ||
- | ===== Rationale ===== | + | The programming language does not enforce that the subtype behaves like the supertype. Method '' |
+ | |||
+ | |||
+ | ===== Rationale ===== | ||
+ | |||
+ | Let '' | ||
===== Strategies ===== | ===== Strategies ===== | ||
* Only strengthen invariants in subclasses; never weaken them | * Only strengthen invariants in subclasses; never weaken them | ||
- | * Only waken preconditions when overriding methods | + | * Only weaken |
* Only strengthen postconditions when overriding methods | * Only strengthen postconditions when overriding methods | ||
* Use Delegation instead of Inheritance | * Use Delegation instead of Inheritance | ||
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===== Origin ===== | ===== Origin ===== | ||
- | Barbara Liskov: //[[http://portal.acm.org/ | + | Barbara Liskov: //[[http://citeseerx.ist.psu.edu/ |
===== Evidence ===== | ===== Evidence ===== | ||
/* Comment out what is not applicable and explain the rest: */ | /* Comment out what is not applicable and explain the rest: */ | ||
- | /* | + | |
- | * [[wiki: | + | /* * [[wiki: |
- | * [[wiki: | + | |
- | * [[wiki: | + | * [[wiki: |
- | * [[wiki: | + | * [[wiki: |
- | */ | + | |
+ | /* * [[wiki: | ||
===== Relations to Other Principles ===== | ===== Relations to Other Principles ===== | ||
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===== Description Status ===== | ===== Description Status ===== | ||
/* Choose one of the following and comment out the rest: */ | /* Choose one of the following and comment out the rest: */ | ||
- | [[wiki: | + | /*[[wiki: |
- | /*[[wiki: | + | [[wiki: |
/ | / | ||
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* [[wiki> | * [[wiki> | ||
* [[wp> | * [[wp> | ||
+ | * Barbara H. Liskov , Jeanette M. Wing: // | ||
+ | * Barbara H. Liskov , Jeanette M. Wing: // | ||
+ | |||
+ | ===== Discussion ===== | ||
+ | Discuss this wiki article and the principle on the corresponding [[talk: |
principles/liskov_substitution_principle.txt · Last modified: 2021-10-18 21:50 by christian