preconditions

Liquibase preconditions: How do I check for a column being non-nullable?

由 痞子三分冷 提交于 2019-12-12 09:37:42
问题 I have a db upgrade script to remove the non-null constraint on a column. I want to do a precondition check, and call ALTER TABLE only when it is non-null. The master.xml script is a progressive one where I keep adding scripts and the entire thing runs everytime. After the first time my Alter Table script has run, I do not want it to be run again. Couldn't find a predefined precondition for this, and could not write an sqlcheck either. 回答1: Can be done with sqlCheck. For MySql <preConditions

liquibase preconditions yaml

由 白昼怎懂夜的黑 提交于 2019-12-10 15:13:35
问题 Is it possible to use Precondition in YAML i didn't find any sources except this page http://www.liquibase.org/documentation/yaml_format.html But I am looking for the equivalent of : <changeSet id="addColumn-example"> <preConditions onFail="MARK_RAN"> <columnExists schemaName="earls" tableName="category" columnName="display_name"/> </preConditions> <dropColumn columnName="display_name" schemaName="earls" tableName="category"/> </changeSet> So my natural translation will be : changeSet: id:

How do I insert a precondition in a java class method or constructor?

由 蹲街弑〆低调 提交于 2019-12-10 03:59:53
问题 This is for a java class I'm taking. The book mentions preconditions and postconditions but doesn't give any examples how to code them. It goes on to talk about asserts, I have that down, but the assignment I'm doing specifically states to insert preconditions and test the preconditions with asserts. Any help would be great. 回答1: Languages like Eiffel support "preconditions" and "postconditions" as a basic part of the language. One can make a compelling argument that the whole purpose of an

Slow Scala assert

由 懵懂的女人 提交于 2019-12-08 16:16:38
问题 We've been profiling our code recently and we've come across a few annoying hotspots. They're in the form assert(a == b, a + " is not equal to " + b) Because some of these asserts can be in code called a huge amount of times the string concat starts to add up. assert is defined as: def assert(assumption : Boolean, message : Any) = .... why isn't it defined as: def assert(assumption : Boolean, message : => Any) = .... That way it would evaluate lazily. Given that it's not defined that way is

PHPDoc preconditions

由 ╄→гoц情女王★ 提交于 2019-12-07 18:48:48
问题 How to tag preconditions with PHPDoc? I have an object, and before calling a function another function must have been called: $myObject = new MyClass(); $myObject->mustDoThis(); $myObject->beforeThis(); So the documentation for beforeThis() would look like: /** * @precondition mustDoThis() must be called before this function is */ Or is there another way around this? Perhaps a @throw clause would be enough. 回答1: As far as I know, there's no standard @precondition or @postcondition tags for

Are preconditions and postconditions needed in addition to invariants in member functions if doing design by contract?

由 好久不见. 提交于 2019-12-07 09:34:05
问题 I understand that in the DbC method, preconditions and postconditions are attached to a function. What I'm wondering is if that applies to member functions as well. For instance, assuming I use invariants at the beginning at end of each public function, a member function will look like this: edit: (cleaned up my example) void Charcoal::LightOnFire() { invariant(); in_LightOnFire(); StartBurning(); m_Status = STATUS_BURNING; m_Color = 0xCCCCCC; return; // last return in body out_LightOnFire();

PHPDoc preconditions

由 北城以北 提交于 2019-12-06 05:57:09
How to tag preconditions with PHPDoc? I have an object, and before calling a function another function must have been called: $myObject = new MyClass(); $myObject->mustDoThis(); $myObject->beforeThis(); So the documentation for beforeThis() would look like: /** * @precondition mustDoThis() must be called before this function is */ Or is there another way around this? Perhaps a @throw clause would be enough. As far as I know, there's no standard @precondition or @postcondition tags for PhpDoc but I use them anyway as it is a nice way to hint the developer implementing the class/interface/trait.

Are preconditions and postconditions needed in addition to invariants in member functions if doing design by contract?

由 落爺英雄遲暮 提交于 2019-12-05 15:55:13
I understand that in the DbC method, preconditions and postconditions are attached to a function. What I'm wondering is if that applies to member functions as well. For instance, assuming I use invariants at the beginning at end of each public function, a member function will look like this: edit: (cleaned up my example) void Charcoal::LightOnFire() { invariant(); in_LightOnFire(); StartBurning(); m_Status = STATUS_BURNING; m_Color = 0xCCCCCC; return; // last return in body out_LightOnFire(); invariant(); } inline void Charcoal::in_LightOnFire() { #ifndef _RELEASE_ assert (m_Status == STATUS

How do I insert a precondition in a java class method or constructor?

由 陌路散爱 提交于 2019-12-05 05:57:26
This is for a java class I'm taking. The book mentions preconditions and postconditions but doesn't give any examples how to code them. It goes on to talk about asserts, I have that down, but the assignment I'm doing specifically states to insert preconditions and test the preconditions with asserts. Any help would be great. Languages like Eiffel support "preconditions" and "postconditions" as a basic part of the language. One can make a compelling argument that the whole purpose of an "object constructor" is precisely to establish "the class invariant". But with Java (as with just about every

Liquibase preconditions: How do I check for a column being non-nullable?

由 泄露秘密 提交于 2019-12-05 04:44:15
I have a db upgrade script to remove the non-null constraint on a column. I want to do a precondition check, and call ALTER TABLE only when it is non-null. The master.xml script is a progressive one where I keep adding scripts and the entire thing runs everytime. After the first time my Alter Table script has run, I do not want it to be run again. Couldn't find a predefined precondition for this, and could not write an sqlcheck either. Can be done with sqlCheck. For MySql <preConditions onFail="MARK_RAN" onError="CONTINUE"> <sqlCheck expectedResult="NO"> SELECT is_Nullable FROM INFORMATION
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