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https://issues.apache.org/jira/browse/OFBIZ-10593?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16642276#comment-16642276
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Mathieu Lirzin edited comment on OFBIZ-10593 at 10/8/18 6:28 PM:
-----------------------------------------------------------------
Hello,
So after looking at the hierarchy it appears that the extra arguments are not
desirable. In fact there is a design issue where {{EntityOperator}} and
{{EntityConditionValue}} inherits from {{EntityConditionBase}} even if they
can't be considered as proper "entity conditions". This violates the principle
of prefering delegation over inheritance. This should be fixed later by some
refactoring.
In the meantime, I have updated
[^OFBIZ-10593_Fixed-Implement-EntityConditionVisitor-properly.patch] to only
consider subclasses of the {{EntityCondition}} abstract class. Here is the
{{EntityConditionVisitor}} interface I consider acceptable to be applied and
which can be used in OFBIZ-10579:
{code:java}
public interface EntityConditionVisitor {
void visit(EntityConditionFunction cond);
<T extends EntityCondition> void visit(EntityConditionList<T> cond);
void visit(EntityFieldMap fieldMap);
void visit(EntityDateFilterCondition condition);
void visit(EntityExpr expr);
void visit(EntityWhereString condition);
}
{code}
was (Author: mthl):
Hello,
So after looking at the hierarchy it appears that the extra arguments are not
desirable. In fact there is a design issue where {{EntityOperator}} and
{{EntityConditionValue}} inherits from {{EntityConditionBase}} even if they
can't be considered as proper "entity conditions". This violates the principle
of prefering delegation over inheritance. This should be fixed later by some
refactoring.
In the meantime, I have updated the visitor to only consider subclasses of the
{{EntityCondition}} abstract class. Here is the {{EntityConditionVisitor}}
interface I consider acceptable to be applied and which can be used in
OFBIZ-10579.
{code:java}
public interface EntityConditionVisitor {
void visit(EntityConditionFunction cond);
<T extends EntityCondition> void visit(EntityConditionList<T> cond);
void visit(EntityFieldMap fieldMap);
void visit(EntityDateFilterCondition condition);
void visit(EntityExpr expr);
void visit(EntityWhereString condition);
}
{code}
> ‘EntityConditionVisitor’ is a confused visitor pattern
> ------------------------------------------------------
>
> Key: OFBIZ-10593
> URL: https://issues.apache.org/jira/browse/OFBIZ-10593
> Project: OFBiz
> Issue Type: Improvement
> Affects Versions: Trunk
> Reporter: Mathieu Lirzin
> Assignee: Mathieu Lirzin
> Priority: Major
> Attachments:
> OFBIZ-10593_Fixed-Implement-EntityConditionVisitor-properly.patch
>
>
> {{EntityConditionVisitor}} interface is supposed to implement the visitor
> pattern which supposes a set of classes meant to be visited using an
> {{accept}} method and a visitor with multiple {{visit}} method overloads (one
> for each visited class).
> Currently {{EntityConditionVisitor}} contains both {{accept}} and {{visit}}
> methods which make *no sense*
> {code:java}
> public interface EntityConditionVisitor {
> <T> void visit(T obj);
> <T> void accept(T obj);
> void acceptObject(Object obj);
> void acceptEntityCondition(EntityCondition condition);
> <T extends EntityCondition> void
> acceptEntityJoinOperator(EntityJoinOperator op, List<T> conditions);
> <L,R,T> void acceptEntityOperator(EntityOperator<L, R, T> op, L lhs, R
> rhs);
> <L,R> void acceptEntityComparisonOperator(EntityComparisonOperator<L, R>
> op, L lhs, R rhs);
> void acceptEntityConditionValue(EntityConditionValue value);
> void acceptEntityFieldValue(EntityFieldValue value);
> void acceptEntityExpr(EntityExpr expr);
> <T extends EntityCondition> void
> acceptEntityConditionList(EntityConditionList<T> list);
> void acceptEntityFieldMap(EntityFieldMap fieldMap);
> void acceptEntityConditionFunction(EntityConditionFunction func,
> EntityCondition nested);
> <T extends Comparable<?>> void acceptEntityFunction(EntityFunction<T>
> func);
> void acceptEntityWhereString(EntityWhereString condition);
> void acceptEntityDateFilterCondition(EntityDateFilterCondition condition);
> }
> {code}
> this confusion is visible in the {{EntityCondition}} which has both a
> {{visit}} and an {{accept}} method, even if it is only supposed to accept a
> visitor.
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