Reverse Polish Notation Question
Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce Classic
Forum Discription: For .NET 2.0
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=1745
Printed Date: 13-Sep-2025 at 7:44pm
Topic: Reverse Polish Notation Question
Posted By: evanian
Subject: Reverse Polish Notation Question
Date Posted: 23-Apr-2010 at 9:23am
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I am just getting into OQL and I need to build a query of the following algebraic form:
Condition1 AND ((Condition2 AND Condition3) OR (Condition4 AND Condition5)) AND Condition6 Is there a way of doing this? Any help would be greatly appreciated! |
Replies:
Posted By: GregD
Date Posted: 23-Apr-2010 at 5:56pm
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That's a bit of a nasty one, but I think with a little study of the table below (from the Object Persistence chapter of the Developers Guide) you will see how to write your query. You have, algebraically, A and ((B and C) or (D and E)) and F So I believe that translates to A BC and DE and or and F and The operator always applies to the two most recently listed operands. Algebraic Notation v. Reverse-Polish The following table compares algebraic notation to the corresponding Reverse-Polish notation. If you’re accustomed to thinking algebraically, as many of us are, just find the relationships you need in the left-hand column and see the Reverse-Polish equivalent in the right-hand column. Not every possible construction is covered, but with a few minutes of meditation – as especially, with comparison to the examples given above -- you’ll get the idea.  |
Posted By: smi-mark
Date Posted: 23-Apr-2010 at 6:43pm
| That's a great chart, Greg. I still have several projects in DevForce Classic, and it really makes you appreciate LINQ queries in EF!!! |
Posted By: evanian
Date Posted: 26-Apr-2010 at 1:22am
| Thanks, that's just what I needed. I didn't realise that the rule was "the operator always applies to the two most recently listed operands". It finally makes full sense of the table :) |
Posted By: GregD
Date Posted: 26-Apr-2010 at 11:42am
Reverse Polish does have a sort of Vulcan beauty to it; but yeah, I'd have to go with LINQ. 8-) |