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precondition

 
American Heritage Dictionary:

pre·con·di·tion

(prē'kən-dĭsh'ən) pronunciation
n.
A condition that must exist or be established before something can occur or be considered; a prerequisite.

tr.v., -tioned, -tion·ing, -tions.
To condition, train, or accustom in advance.


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Saunders Veterinary Dictionary:

preconditioning

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Preparation of 6 to 8 months old range-reared, recently weaned beef calves for entry into a feedlot and an intensive fattening program. Includes castration, dehorning and branding 3 weeks before and all vaccinations 2 weeks before weaning, and weaning 3 to 4 weeks before sale or entry to the feedlot. During this postweaning period the calf should become accustomed to feedlot feeds and conditions.

Wikipedia on Answers.com:

Precondition

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In computer programming, a precondition is a condition or predicate that must always be true just prior to the execution of some section of code or before an operation in a formal specification.

If a precondition is violated, the effect of the section of code becomes undefined and thus may or may not carry out its intended work. Security problems can arise due to incorrect preconditions.

Often, preconditions are simply included in the documentation of the affected section of code. Preconditions are sometimes tested using assertions within the code itself, and some languages have specific syntactic constructions for doing so.

For example: the factorial is only defined for integers greater than or equal to zero. So a program that calculates the factorial of an input number would have preconditions that the number be an integer and that it be greater than or equal to zero.

Contents

Preconditions in object-oriented programming

Preconditions in object-oriented software development are an essential part of design by contract. Design by contract also includes notions of postcondition and class invariant.

The precondition for any routine defines any constraints on object state which are necessary for successful execution. From the program developer's viewpoint, this constitutes the routine caller's portion of the contract. The caller then is obligated to ensure that the precondition holds prior to calling the routine. The reward for the caller's effort is expressed in the called routines postcondition.[1]

Eiffel example

The routine in the following example written in Eiffel takes as an argument an integer which must be a valid value for an hour of the day, i. e., 0 through 23, inclusively. The precondition follows the keyword require. It specifies that the argument must be greater than or equal to zero and less than or equal to 23. The tag "valid_argument:" describes this precondition clause and serves to identify it in case of a runtime precondition violation.

    set_hour (a_hour: INTEGER)
            -- Set `hour' to `a_hour'
        require
            valid_argument: a_hour >= 0 and a_hour <= 23
        do
            hour := a_hour
        ensure
            hour_set: hour = a_hour
        end

Preconditions and inheritance

In the presence of inheritance, the routines inherited by descendant classes (subclasses) do so with their preconditions in force. This means that any implementations or redefinitions of inherited routines also have to be written to comply with their inherited contract. Preconditions can be modified in redefined routines, but they may only be weakened.[2] That is, the redefined routine may lessen the obligation of the client, but not increase it.

See also

References

  1. ^ Meyer, Bertrand, Object-Oriented Software Construction, second edition, Prentice Hall, 1997, p. 342.
  2. ^ Meyer, 1997, pp. 570–573.

Translations:

Precondition

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Dansk (Danish)
n. - forhåndsbetingelse
v. tr. - forberede

Nederlands (Dutch)
eerste vereiste, voorwaarde vooraf

Français (French)
n. - condition requise
v. tr. - (Psych) conditionner

Deutsch (German)
n. - Vorbedingung
v. - einstellen, vorbereiten

Ελληνική (Greek)
n. - (απαραίτητη) προϋπόθεση
v. - προδιαθέτω

Italiano (Italian)
requisito indispensabile

Português (Portuguese)
n. - pré-condição (f)
v. - precondicionar

Русский (Russian)
предварительное условие

Español (Spanish)
n. - condición previa
v. tr. - precondicionar

Svenska (Swedish)
n. - förhandsvillkor
v. - förbehandla, göra färdig

中文(简体)(Chinese (Simplified))
先决条件, 事先准备, 事先训练

中文(繁體)(Chinese (Traditional))
n. - 先決條件
v. tr. - 事先準備, 事先訓練

한국어 (Korean)
n. - 견제[선결]조건
v. tr. - 미리 조정하다

日本語 (Japanese)
v. - あらかじめ調整する
n. - 前提条件

العربيه (Arabic)
‏(الاسم) شرط مسبق (فعل) يشرط مسبقا‏

עברית (Hebrew)
n. - ‮תנאי מוקדם‬
v. tr. - ‮הביא מראש למצב הרצוי‬


 
 

 

Copyrights:

American Heritage Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Roget's Thesaurus. Roget's II: The New Thesaurus, Third Edition by the Editors of the American Heritage® Dictionary Copyright © 1995 byHoughton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.  Read more
Saunders Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
Wikipedia on Answers.com. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article Precondition Read more
Translations. Copyright © 2007, WizCom Technologies Ltd. All rights reserved.  Read more

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