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  • Fast language for problem solving? [closed]

    - by Friend of Kim
    I learned PHP to make websites. After some years I've started using programming for solving what is difficult tasks for my level. Now I want to make a program that solves equations. (I want to write it myself, not use an API. Because I'm doing this for the sake of the challenge, not for the result..) Because of this, I'm going to learn a new and faster/better language. It's going to be C++, Java, Python or C#. What are the benefits of each language, and which language is best for speed compared to speed of writing and readability? Using C would be lightning fast, but the lack of OO is making for more complex code and reduces the readability, for example..

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  • MySQL 5 multiple JOIN syntax not working in MySQL 4

    - by draco
    Hello all, the current SQL query works fine locally on MAMP 1.8.4 running MySQL 5.1.37. SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU USING (users_id) JOIN events_admins EA USING (admins_id) ORDER BY EL.log_id DESC LIMIT 0, 10 However, when I bring this query live to production server which is running MySQL 4.1.22-standard, the following error occurred (whether or not there are data in the entry). A Database Error Occurred Error Number: 1054 Unknown column 'sceclub_exclaim2007.EU.admins_id' in 'on clause' SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU USING (users_id) JOIN events_admins EA USING (admins_id) ORDER BY EL.log_id DESC LIMIT 0, 20 This is based on CodeIgniter 1.7.2 and both production and development are running the same set of database. Database tables events_users: users_id users_name users_credits users_matric users_redeem events_admins: admins_id admins_email admins_name admins_pass admins_date admins_modified admins_last_login events_attendance: attendance_id users_id events_id events_events: events_id events_name events_venue events_time events_desc events_pass events_log:log_id admins_id log_actions log_date log_value users_id log_type I'm new to MySQL so I'm not aware of any difference in versions or what could be a possible cause, thank you in advance! Tried googling for MySQL4 difference to no avail too. Also tried using SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU where EL.users_id = EU.users_id JOIN events_admins EA USING EL.admins_id = EA.admins_id ORDER BY EL.log_id DESC LIMIT 0, 10 But then I got the error in both production and development. A Database Error Occurred Error Number: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'JOIN events_admins EA USING EL.admins_id = EA.admins_id ORDER BY' at line 8 SELECT EL.log_actions, EL.log_date, EL.log_value, EL.log_type, EA.admins_name, EU.users_name, EU.users_matric FROM events_log EL JOIN events_users EU where EL.users_id = EU.users_id JOIN events_admins EA USING EL.admins_id = EA.admins_id ORDER BY EL.log_id DESC LIMIT 0, 20 If you can point me to some resources where I can read up more on MySQL 4 syntax to achieve the same thing effect like I did with MySQL 5 syntax, please let me know. Thanks again!

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  • Komodo Edit 5.2 Django Template Syntax Error - Info: <head> previously mentioned

    - by Lance McNearney
    I am using Komodo Edit 5.2 for editing html and Django template files. It always shows a single syntax error inside the first {% block %} area on the first tag of my template. For example: {% extends "base.html" %} {% load i18n %} {% block title %}Hello{% endblock %} {% block content %} <p>Hello</p> <-- Syntax error on this single line <p>Other lines have no errors</p> {% endblock %} {% block footer %} <p>No errors here</p> {% endblock %} The syntax error given is: Info: <head> previously mentioned I know for a fact that the error has nothing to do with my <head> tag since it occurs in the base template and in child templates (and the IDE isn't smart enough to process the base templates when in a child, etc.) All of my html tags are closed properly and everything validates for XHTML strict. This forum post mentions a similar problem but offers no solution (and may be specific to Smarty syntax highlighting). Any ideas on how to resolve this error (or disable it from being shown)?

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  • Static method , Abstract method , Interface method comparision ?

    - by programmerist
    When i choose these methods? i can not decide which one i must prefer or when will i use one of them?which one give best performance? First Type Usage public abstract class _AccessorForSQL { public virtual bool Save(string sp, ListDictionary ld, CommandType cmdType); public virtual bool Update(); public virtual bool Delete(); public virtual DataSet Select(); } class GenAccessor : _AccessorForSQL { DataSet ds; DataTable dt; public override bool Save(string sp, ListDictionary ld, CommandType cmdType) { } public override bool Update() { return true; } public override bool Delete() { return true; } public override DataSet Select() { DataSet dst = new DataSet(); return dst; } Second Type Usage Also i can write it below codes: public class GenAccessor { public Static bool Save() { } public Static bool Update() { } public Static bool Delete() { } } Third Type Usage Also i can write it below codes: public interface IAccessorForSQL { bool Delete(); bool Save(string sp, ListDictionary ld, CommandType cmdType); DataSet Select(); bool Update(); } public class _AccessorForSQL : IAccessorForSQL { private DataSet ds; private DataTable dt; public virtual bool Save(string sp, ListDictionary ld, CommandType cmdType) { } } } I can use first one below usage: GenAccessor gen = New GenAccessor(); gen.Save(); I can use second one below usage: GenAccessor.Save(); Which one do you prefer? When will i use them? which time i need override method ? which time i need static method?

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  • Looking for Antlr Grammar syntaxt highlight in VS2010

    - by David Mårtensson
    I am looking for some way to edit antlr grammar files directly within VS2010 with syntax highlight. I have used antlrworks a lot but it has the drawback that I have to start antlrworks separately and then browse to the file I want to edit, do the changed and save. For minor fixes I do not need all the tools in Antlrworks but I still would like the syntax highlight. But I have not been able to get VS2010 to open antlrworks with the right file and I have found no other way to get syntax highlight directly within VS2010 editor, it just opens as plain text. I can get visual studio to open antlrworks but it will open with only the last set of files it had open, not the one I clicked on. So my question(s) are: Is there a way to get antlrworks to open with the right file when I double click in it in visual studio project explorer? Is there any other way to get correct syntax highlight for antlr grammar files within visual studio (or with another editor, preferably not one that costs money, but if there are no free ones a commercial one might be an option).

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  • Class Structure w/ LINQ, Partial Classes, and Abstract Classes

    - by Jason
    I am following the Nerd Dinner tutorial as I'm learning ASP.NET MVC, and I am currently on Step 3: Building the Model. One part of this section discusses how to integrate validation and business rule logic with the model classes. All this makes perfect sense. However, in the case of this source code, the author only validates one class: Dinner. What I am wondering is, say I have multiple classes that need validation (Dinner, Guest, etc). It doesn't seem smart to me to repeatedly write these two methods in the partial class: public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } partial void OnValidate(ChangeAction action) { if (!IsValid) { throw new ApplicationException("Rule violations prevent saving."); } } What I'm wondering is, can you create an abstract class (because "GetRuleViolations" needs to be implemented separately) and extend a partial class? I'm thinking something like this (based on his example): public partial class Dinner : Validation { public IEnumerable<RuleViolation> GetRuleViolations() { yield break; } } This doesn't "feel" right, but I wanted to check with SO to get opinions of individuals smarter than me on this. I also tested it out, and it seems that the partial keyword on the OnValidate method is causing problems (understandably so). This doesn't seem possible to fix (but I could very well be wrong). Thanks!

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  • EF4 and multiple abstract levels

    - by Cedric
    I need to use inheritance with EF4 and the TPH model created from DB. I created a new projet to test simples classes. There is my class model: There is my table in SQL SERVER 2008 : VEHICLE ID : int PK Owner : varchar(50) Consumption : float FirstCirculationDate : date Type : varchar(50) Discriminator : varchar(10) I added a condition in my EDMX on the Discriminator field to differentiate the Scooter, Car, Motorbike and Bike entities. MotorizedVehicle and Vehicle are Abstract. But when I compile, this error appears : Error 3032: Problem in mapping fragments starting at lines 78, 85:EntityTypes EF4InheritanceModel.Scooter, EF4InheritanceModel.Motorbike, EF4InheritanceModel.Car, EF4InheritanceModel.Bike are being mapped to the same rows in table Vehicle. Mapping conditions can be used to distinguish the rows that these types are mapped to. Edit : To Ladislav : I try it and error change to become it for all of my entities : Error 3034: Problem in mapping fragments starting at lines 72, 86:An entity is mapped to different rows within the same table. Ensure these two mapping fragments do not map two groups of entities with overlapping keys to two distinct groups of rows. To Henk (with Ladislay suggestion) : There are all of mappings details : What's wrong ? Thanks

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  • Saving Abstract and Sub classes to database

    - by bretddog
    Hi, I have an abstract class "StrategyBase", and a set of sub classes, StrategyA/B/C etc. The sub classes use some of the properties of the base class, and have some individual properties. My question is how to save this to a database. I'm currently using SqlCE, and Linq-To-Sql by creating entity classes automatically with SqlMetal.exe. I've seen there are three solutions shown in this question, but I'm not able to see how these solutions will work or not with SqlMetal/entity classes. Though it seems to me the "concrete table inheritance" would probably work without any manual modifying. What about the other two, would they be problematic? For "Single Table Inheritance" wouldn't all classes get all variables, even though they don't need them? And for the "Class table inheritance" solution I can't really see at all how that will map into the entity-classes for a useful purpose. I may note that I extend these partial entity classes for making the classes of my business objects. I may also consider moving to EntityFramework instead of SqlMetal/Linq2Sql, so would be nice also to know if that makes any difference to what schema is easy to implement. One likely important thing to note is that I will constantly be develop new strategies, which makes me have to modify the program code, and probably the database shcema; when adding a new strategy. Sorry the question is a bit "all over the place", but hopefully it's some clear advantages/disadvantages here that you may be able to advice. ? Cheers!

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  • In Ruby, why is a method invocation not be able to be treated as a unit when "do" and "end" is used?

    - by Jian Lin
    The following question is related to the question "Ruby Print Inject Do Syntax". My question is, can we insist on using do and end and make it work with puts or p? This works: a = [1,2,3,4] b = a.inject do |sum, x| sum + x end puts b # prints out 10 so, is it correct to say, inject is a class method of the Array class, which takes a block of code, and then returns a number. If so, then it should be no different from calling a function and getting back a return value: b = foo(3) puts b or b = circle.getRadius() puts b In the above two cases, we can directly say puts foo(3) puts circle.getRadius() so, there is no way to make it work directly by using the following 2 ways: a = [1,2,3,4] puts a.inject do |sum, x| sum + x end but it gives ch01q2.rb:7:in `inject': no block given (LocalJumpError) from ch01q2.rb:4:in `each' from ch01q2.rb:4:in `inject' from ch01q2.rb:4 grouping the method call using ( ) doesn't work either: a = [1,2,3,4] puts (a.inject do |sum, x| sum + x end) and this gives: ch01q3.rb:4: syntax error, unexpected kDO_BLOCK, expecting ')' puts (a.inject do |sum, x| ^ ch01q3.rb:4: syntax error, unexpected '|', expecting '=' puts (a.inject do |sum, x| ^ ch01q3.rb:6: syntax error, unexpected kEND, expecting $end end) ^ finally, the following version works: a = [1,2,3,4] puts a.inject { |sum, x| sum + x } but why doesn't the grouping of the method invocation using ( ) work in the earlier example? What if a programmer insist that he uses do and end, can it be made to work?

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  • In Ruby, why does a method invocation not be able to be treated as a unit when "do" and "end" is use

    - by Jian Lin
    The following question is related to http://stackoverflow.com/questions/2127836/ruby-print-inject-do-syntax The question is, can we insist on using DO and END and make it work with puts or p? This works: a = [1,2,3,4] b = a.inject do |sum, x| sum + x end puts b # prints out 10 so, is it correct to say, inject is a class method of the Array class, which takes a block of code, and then returns a number. If so, then it should be no different from calling a function and getting back a return value: b = foo(3) puts b or b = circle.getRadius() puts b In the above two cases, we can directly say puts foo(3) puts circle.getRadius() so, there is no way to make it work directly by using the following 2 ways: a = [1,2,3,4] puts a.inject do |sum, x| sum + x end but it gives ch01q2.rb:7:in `inject': no block given (LocalJumpError) from ch01q2.rb:4:in `each' from ch01q2.rb:4:in `inject' from ch01q2.rb:4 grouping the method call using ( ) doesn't work either: a = [1,2,3,4] puts (a.inject do |sum, x| sum + x end) and this gives: ch01q3.rb:4: syntax error, unexpected kDO_BLOCK, expecting ')' puts (a.inject do |sum, x| ^ ch01q3.rb:4: syntax error, unexpected '|', expecting '=' puts (a.inject do |sum, x| ^ ch01q3.rb:6: syntax error, unexpected kEND, expecting $end end) ^ finally, the following version works: a = [1,2,3,4] puts a.inject { |sum, x| sum + x } but why doesn't the grouping of the method invocation using ( ) work? What if a programmer insists that he uses do and end, can it be made to work directly with p or puts, without an extra temporary variable?

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  • xcode project-/target-settings-syntax for linker flag force_load on iPhone

    - by Kaiserludi
    Hi all. I am confronted with the double bind, that on the one hand for one of the 3rd party static libraries, my iPhone application uses, the linker flag -all_load has to be set in the application project- or target settings, otherwise the app crashes at runtime not finding some symbols, called internally from the lib, on the other hand for another 3rd party static lib -all_load must not be set on application level, or the app won't build thanks to a "duplicate symbols"-linker error. To solve this issue I now want to use force_load instant of load_all, as it due to documentation it does the same like all_load, but only for the passed path or lib-file, instead of all libs. The problem with force_load is, I do not have a clue, how to pass a path or file as parameter with it, when passing it via xcode project- or target-settings. All syntax-possibilities coming to my mind either lead into xcode thinking its another linker flag instead of a parameter to the previous one, or the linker is throwing syntax related errors or the flag simply does nothing at all in comparison to not being set. I also opened the .pbxproj-file in a text-editor to edit it to the correct command line syntax manually, but when reloading the project with xcode, it auto changes the syntax into interpreting the parameter to force_load as a separate flag. Anyone having an idea on this issue? Thx, Kaiserludi.

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  • Abstract factory pattern on top of IoC?

    - by Sergei
    I have decided to use IoC principles on a bigger project. However, i would like to get something straight that's been bothering me for a long time. The conclusion that i have come up with is that an IoC container is an architectural pattern, not a design pattern. In other words, no class should be aware of its presence and the container itself should be used at the application layer to stitch up all components. Essentially, it becomes an option, on top of a well designed object-oriented model. Having said that, how is it possible to access resolved types without sprinkling IoC containers all over the place (regardless of whether they are abstracted or not)? The only option i see here is to utilize abstract factories which use an IoC container to resolve concrete types. This should be easy enough to swap out for a set of standard factories. Is this a good approach? Has anyone on here used it and how well did it work for you? Is there anything else available? Thanks!

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  • Why should I abstract my data layer?

    - by Gazillion
    OOP principles were difficult for me to grasp because for some reason I could never apply them to web development. As I developed more and more projects I started understanding how some parts of my code could use certain design patterns to make them easier to read, reuse, and maintain so I started to use it more and more. The one thing I still can't quite comprehend is why I should abstract my data layer. Basically if I need to print a list of items stored in my DB to the browser I do something along the lines of: $sql = 'SELECT * FROM table WHERE type = "type1"';' $result = mysql_query($sql); while($row = mysql_fetch_assoc($result)) { echo '<li>'.$row['name'].'</li>'; } I'm reading all these How-Tos or articles preaching about the greatness of PDO but I don't understand why. I don't seem to be saving any LoCs and I don't see how it would be more reusable because all the functions that I call above just seem to be encapsulated in a class but do the exact same thing. The only advantage I'm seeing to PDO are prepared statements. I'm not saying data abstraction is a bad thing, I'm asking these questions because I'm trying to design my current classes correctly and they need to connect to a DB so I figured I'd do this the right way. Maybe I'm just reading bad articles on the subject :) I would really appreciate any advice, links, or concrete real-life examples on the subject!

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  • In Ruby, why is a method invocation not able to be treated as a unit when "do" and "end" is used?

    - by Jian Lin
    The following question is related to the question "Ruby Print Inject Do Syntax". My question is, can we insist on using do and end and make it work with puts or p? This works: a = [1,2,3,4] b = a.inject do |sum, x| sum + x end puts b # prints out 10 so, is it correct to say, inject is an instance method of the Array object, and this instance method takes a block of code, and then returns a number. If so, then it should be no different from calling a function or method and getting back a return value: b = foo(3) puts b or b = circle.getRadius() puts b In the above two cases, we can directly say puts foo(3) puts circle.getRadius() so, there is no way to make it work directly by using the following 2 ways: a = [1,2,3,4] puts a.inject do |sum, x| sum + x end but it gives ch01q2.rb:7:in `inject': no block given (LocalJumpError) from ch01q2.rb:4:in `each' from ch01q2.rb:4:in `inject' from ch01q2.rb:4 grouping the method call using ( ) doesn't work either: a = [1,2,3,4] puts (a.inject do |sum, x| sum + x end) and this gives: ch01q3.rb:4: syntax error, unexpected kDO_BLOCK, expecting ')' puts (a.inject do |sum, x| ^ ch01q3.rb:4: syntax error, unexpected '|', expecting '=' puts (a.inject do |sum, x| ^ ch01q3.rb:6: syntax error, unexpected kEND, expecting $end end) ^ finally, the following version works: a = [1,2,3,4] puts a.inject { |sum, x| sum + x } but why doesn't the grouping of the method invocation using ( ) work in the earlier example? What if a programmer insist that he uses do and end, can it be made to work?

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  • async tree jquery easy ui

    - by user765368
    I'm trying to create an Async Tree in jQuery Easy Ui. I understand the idea behind it, but will this work if my root node is not a node that is coming from the database or something (therefore, it does not have any id). My root node is some node that I define myself. How would I make an async tree in jquery easy ui to load a bunch of nodes as children of my root node (which, again has no id because it's not coming from the database. My children nodes are coming from the database though). I hope y'all understand what I'm trying to do here. Any help please

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  • Tree View / File View Control for C#

    - by Jason
    I have been looking for a C# tree control for displaying a file system that has the following capabilities: Select a starting directory. I don't always want to start at a "default" top directory level. The ability to grab an event when the user double clicks on a file in the tree. I want to handle opening the file within my application. I have been looking at this C# File Browser. Unfortunately, I have not been able to figure out how to do meet my second need. (If anybody can clear that up for me, I would like that even better.) Thanks for any help.

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  • complicated graphviz tree structure

    - by thomas
    Hello. I am trying to create a tree structure with graphviz. I am open to either writing the graphviz code by hand or using the ruby-graphviz gem for ruby. Given the below picture can anyone provide any insight on the necessary code? Ignore that the lines are not straight...they should be when graphviz builds the graph. I am open to having dots/points when lines intersect as well. I have played with ruby-graphviz and the family tree class...this is getting me part of the way there but I really need all lines to be straight and intersect at right angles and the out-of-the-box code doesn't seem to do that.

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  • JavaScript tree / treegrid libraries

    - by desau
    I'm looking for a good JavaScript tree / treegrid package. Now -- before you answer: It needs to be able to perform well with lots of nodes. Perhaps 1,000 sibling nodes. It needs to be able to draw to a usable state within 2 or 3 seconds with 1,000 nodes. It doesn't necessarily need to draw all 1,000 nodes at once -- if it supports some sort of "smart rendering" or fake scrolling. Beyond that, column resizing, drag and drop, inline editing would all be nice, although I could probably add that functionality myself. I've already tried dojo's tree and yahoo's YUI treeview. Both are too slow.

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  • Build and render infinite hierarchical category tree from self-referential category table

    - by FreshCode
    I have a Categories table in which each category has a ParentId that can refer to any other category's CategoryId that I want to display as multi-level HTML list, like so: <ul class="tree"> <li>Parent Category <ul> <li>1st Child Category <!-- more sub-categories --> </li> <li>2nd Child Category <!-- more sub-categories --> </li> </ul> </li> </ul> Presently I am recursively rendering a partial view and passing down the next category. It works great, but it's wrong because I'm executing queries in a view. How can I render the list into a tree object and cache it for quick display every time I need a list of all hierarchical categories?

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  • MS SQL server and Trees

    - by Julian
    Im looking for some way of extrating data form a tree table as defined below. Table Tree Defined as :- TreeID uniqueidentifier TreeParent uniqueidentifier TreeCode varchar(50) TreeDesc varchar(100) Data some (23k rows), Parent Refs back into ID in table The following SQL renders the whole tree (takes arround 2 mins 30) I need to do the following. 1) Render each Tree Node with its LVL 1 parent 2) Render all nodes that have a Description that matches a TreeDesc like 'SomeText%' 3) Render all parent nodes that are for a single tree id. Items 2 and 3 take 2mins30 so this needs to be a lot faster! Item 1, just cant work out how to do it with out killing SQL or taking forever any sugestions would be helpfull Thanks Julian WITH TreeCTE(TreeCode, TreeDesc, depth, TreeParent, TreeID) AS ( -- anchor member SELECT cast('' as varchar(50)) as TreeCode , cast('Trees' as varchar(100)) as TreeDesc, cast('0' as Integer) as depth, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier) as TreeID UNION ALL -- recursive member SELECT s.TreeCode, s.TreeDesc, cte.depth+1, isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)), isnull(s.TreeID, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) FROM pdTrees AS S JOIN TreeCTE AS cte ON isnull(s.TreeParent, cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) = isnull( cte.TreeID , cast('00000000-0000-0000-0000-000000000000' as uniqueidentifier)) ) -- outer query SELECT s.TreeID, s.TreeCode, s.TreeDesc, s.depth, s.TreeParent FROM TreeCTE s

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  • Code to apply expression tree directly to List

    - by Gamma Vega
    Is there a method call in Linq that will apply a expression tree directly on a List<V>? For instance, if I have a expression tree that is built on Order type, and i have a collection of List<Order> items on which i need to apply this expression. I am looking something similar to: class OrderListStore : IQueryable<V>, <other interfaces required to implement custom linq provider> { List<Order> orders; public Expression Expression { get { return Expression.Constant(this); } } IEnumerator<V> IEnumerable<V>.GetEnumerator() { //Here I need to have a method that will take the existing expression //and directly apply on list something like this .. Expression.Translate(orders); } } Any help in this regard is highly appreciated.

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  • Code Golf Christmas Edition: How to print out a Christmas tree of height N

    - by TheSoftwareJedi
    Given a number N, how can I print out a Christmas tree of height N using the least number of code characters? N is assumed constrained to a min val of 3, and a max val of 30 (bounds and error checking are not necessary). N is given as the one and only command line argument to your program or script. All languages appreciated, if you see a language already implemented and you can make it shorter, edit if possible - comment otherwise and hope someone cleans up the mess. Include newlines and whitespace for clarity, but don't include them in the character count. A Christmas tree is generated as such, with its "trunk" consisting of only a centered "*" N = 3: * *** ***** * N = 4: * *** ***** ******* * N = 5: * *** ***** ******* ********* * N defines the height of the branches not including the one line trunk. Merry Christmas SO!

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