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  • Python - 2 Questions: Editing a variable in a function and changing the order of if else statements

    - by Eric
    First of all, I should explain what I'm trying to do first. I'm creating a dungeon crawler-like game, and I'm trying to program the movement of computer characters/monsters in the map. The map is basically a Cartesian coordinate grid. The locations of characters are represented by tuples of the x and y values, (x,y). The game works by turns, and in a turn a character can only move up, down, left or right 1 space. I'm creating a very simple movement system where the character will simply make decisions to move on a turn by turn basis. Essentially a 'forgetful' movement system. A basic flow chart of what I'm intending to do: Find direction towards destination Make a priority list of movements to be done using the direction eg.('r','u','d','l') means it would try to move right first, then up, then down, then left. Try each of the possibilities following the priority order. If the first movement fails (blocked by obstacle etc.), then it would successively try the movements until the first one that is successful, then it would stop. At step 3, the way I'm trying to do it is like this: def move(direction,location): try: -snip- # Tries to move, raises the exception Movementerror if cannot move in the direction return 1 # Indicates movement successful except Movementerror: return 0 # Indicates movement unsuccessful (thus character has not moved yet) prioritylist = ('r','u','d','l') if move('r',location): pass elif move('u',location): pass elif move('d',location): pass elif move('l',location): pass else: pass In the if/else block, the program would try the first movement on the priority on the priority list. At the move function, the character would try to move. If the character is not blocked and does move, it returns 1, leading to the pass where it would stop. If the character is blocked, it returns 0, then it tries the next movement. However, this results in 2 problems: How do I edit a variable passed into a function inside the function itself, while returning if the edit is successful? I have been told that you can't edit a variable inside a function as it won't really change the value of the variable, it just makes the variable inside the function refer to something else while the original variable remain unchanged. So, the solution is to return the value and then assign the variable to the returned value. However, I want it to return another value indicating if this edit is successful, so I want to edit this variable inside the function itself. How do I do so? How do I change the order of the if/else statements to follow the order of the priority list? It needs to be able to change during runtime as the priority list can change resulting in a different order of movement to try.

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  • SQL SERVER – Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. When we look at above resultset it is very clear that LEAD function gives us value which is going to come in next line and LAG function gives us value which was encountered in previous line. If we have to generate the same result without using this function we will have to use self join. In future blog post we will see the same. Let us explore this function a bit more. This function not only provide previous or next line but it can also access any line before or after using offset. Let us fun following query, where LEAD and LAG function accesses the row with offset of 2. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. You can see the LEAD and LAG functions  now have interval of  rows when they are returning results. As there is interval of two rows the first two rows in LEAD function and last two rows in LAG function will return NULL value. You can easily replace this NULL Value with any other default value by passing third parameter in LEAD and LAG function. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where NULL are now replaced with value 0. Just like any other analytic function we can easily partition this function as well. Let us see the use of PARTITION BY in this clause. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where now the data is partitioned by SalesOrderID and LEAD and LAG functions are returning the appropriate result in that window. As now there are smaller partition in my query, you will see higher presence of NULL. In future blog post we will see how this functions are compared to SELF JOIN. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – OVER clause with FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 – ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING

    - by pinaldave
    Yesterday I had discussed two analytical functions FIRST_VALUE and LAST_VALUE. After reading the blog post I received very interesting question. “Don’t you think there is bug in your first example where FIRST_VALUE is remain same but the LAST_VALUE is changing every line. I think the LAST_VALUE should be the highest value in the windows or set of result.” I find this question very interesting because this is very commonly made mistake. No there is no bug in the code. I think what we need is a bit more explanation. Let me attempt that first. Before you do that I suggest you read yesterday’s blog post as this question is related to that blog post. Now let’s have fun following query: USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO The above query will give us the following result: As per the reader’s question the value of the LAST_VALUE function should be always 114 and not increasing as the rows are increased. Let me re-write the above code once again with bit extra T-SQL Syntax. Please pay special attention to the ROW clause which I have added in the above syntax. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Now once again check the result of the above query. The result of both the query is same because in OVER clause the default ROWS selection is always UNBOUNDED PRECEDING AND CURRENT ROW. If you want the maximum value of the windows with OVER clause you need to change the syntax to UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING for ROW clause. Now run following query and pay special attention to ROW clause again. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Here is the resultset of the above query which is what questioner was asking. So in simple word, there is no bug but there is additional syntax needed to add to get your desired answer. The same logic also applies to PARTITION BY clause when used. Here is quick example of how we can further partition the query by SalesOrderDetailID with this new functions. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us windowed resultset on SalesOrderDetailsID as well give us FIRST and LAST value for the windowed resultset. There are lots to discuss for this two functions and we have just explored tip of the iceberg. In future post I will discover it further deep. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • World Record Siebel PSPP Benchmark on SPARC T4 Servers

    - by Brian
    Oracle's SPARC T4 servers set a new World Record for Oracle's Siebel Platform Sizing and Performance Program (PSPP) benchmark suite. The result used Oracle's Siebel Customer Relationship Management (CRM) Industry Applications Release 8.1.1.4 and Oracle Database 11g Release 2 running Oracle Solaris on three SPARC T4-2 and two SPARC T4-1 servers. The SPARC T4 servers running the Siebel PSPP 8.1.1.4 workload which includes Siebel Call Center and Order Management System demonstrates impressive throughput performance of the SPARC T4 processor by achieving 29,000 users. This is the first Siebel PSPP 8.1.1.4 benchmark supporting 29,000 concurrent users with a rate of 239,748 Business Transactions/hour. The benchmark demonstrates vertical and horizontal scalability of Siebel CRM Release 8.1.1.4 on SPARC T4 servers. Performance Landscape Systems Txn/hr Users Call Center Order Management Response Times (sec) 1 x SPARC T4-1 (1 x SPARC T4 2.85 GHz) – Web 3 x SPARC T4-2 (2 x SPARC T4 2.85 GHz) – App/Gateway 1 x SPARC T4-1 (1 x SPARC T4 2.85 GHz) – DB 239,748 29,000 0.165 0.925 Oracle: Call Center + Order Management Transactions: 197,128 + 42,620 Users: 20300 + 8700 Configuration Summary Web Server Configuration: 1 x SPARC T4-1 server 1 x SPARC T4 processor, 2.85 GHz 128 GB memory Oracle Solaris 10 8/11 iPlanet Web Server 7 Application Server Configuration: 3 x SPARC T4-2 servers, each with 2 x SPARC T4 processor, 2.85 GHz 256 GB memory 3 x 300 GB SAS internal disks Oracle Solaris 10 8/11 Siebel CRM 8.1.1.5 SIA Database Server Configuration: 1 x SPARC T4-1 server 1 x SPARC T4 processor, 2.85 GHz 128 GB memory Oracle Solaris 11 11/11 Oracle Database 11g Release 2 (11.2.0.2) Storage Configuration: 1 x Sun Storage F5100 Flash Array 80 x 24 GB flash modules Benchmark Description Siebel 8.1 PSPP benchmark includes Call Center and Order Management: Siebel Financial Services Call Center – Provides the most complete solution for sales and service, allowing customer service and telesales representatives to provide superior customer support, improve customer loyalty, and increase revenues through cross-selling and up-selling. High-level description of the use cases tested: Incoming Call Creates Opportunity, Quote and Order and Incoming Call Creates Service Request . Three complex business transactions are executed simultaneously for specific number of concurrent users. The ratios of these 3 scenarios were 30%, 40%, 30% respectively, which together were totaling 70% of all transactions simulated in this benchmark. Between each user operation and the next one, the think time averaged approximately 10, 13, and 35 seconds respectively. Siebel Order Management – Oracle's Siebel Order Management allows employees such as salespeople and call center agents to create and manage quotes and orders through their entire life cycle. Siebel Order Management can be tightly integrated with back-office applications allowing users to perform tasks such as checking credit, confirming availability, and monitoring the fulfillment process. High-level description of the use cases tested: Order & Order Items Creation and Order Updates. Two complex Order Management transactions were executed simultaneously for specific number of concurrent users concurrently with aforementioned three Call Center scenarios above. The ratio of these 2 scenarios was 50% each, which together were totaling 30% of all transactions simulated in this benchmark. Between each user operation and the next one, the think time averaged approximately 20 and 67 seconds respectively. Key Points and Best Practices No processor cores or cache were activated or deactivated on the SPARC T-Series systems to achieve special benchmark effects. See Also Siebel White Papers SPARC T4-1 Server oracle.com OTN SPARC T4-2 Server oracle.com OTN Siebel CRM oracle.com OTN Oracle Solaris oracle.com OTN Oracle Database 11g Release 2 Enterprise Edition oracle.com OTN Disclosure Statement Copyright 2012, Oracle and/or its affiliates. All rights reserved. Oracle and Java are registered trademarks of Oracle and/or its affiliates. Other names may be trademarks of their respective owners. Results as of 30 September 2012.

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  • How can order of IP addresses issued be controlled?

    - by warren
    Every home router I've setup/used issues addresses from low to high. However, dhcpd from the Internet Systems Consortium seems to issue addresses in reverse order - ie, high to low. Is there a way to change this so that addresses are issued starting at the bottom of the range, and progress higher?

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  • How do I change a VMWare 1.x server's guest boot order?

    - by bo gusman
    I have 4 VMs on a Linux host, call them A, B, C, D running on Z. I really don't care when A and B come up, but I would like to make sure that D comes up before C. I believe that in VMWare 2.x it's possible to change the boot order. Is this possible in 1.x as well? Is this done in /etc/vmware/vm-list? I see that there are a number of VMs listed there, including some that have long since been deleted.

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  • What is the logic behind IE7s Ctrl-Tab order?

    - by torbengb
    Using Ctrl+Tab in Internet Explorer 7 (on Windows XP) seems to follow no sequence that I can work out. Using Shift+Ctrl+Tab even jumps around with no clear logic in what tab order is being followed. It doesn't even work to the reverse as expected from using it in other programs, such as Firefox. Please explain to me how this key combo works in IE7 because I can't figure it out.

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  • What's the logic behind the Ctrl-Tab order in Internet Explorer 7?

    - by torbengb
    Using Ctrl+Tab in Internet Explorer 7 (on Windows XP) seems to follow no sequence that I can work out. Using Shift+Ctrl+Tab even jumps around with no clear logic in what tab order is being followed. It doesn't even work to the reverse as expected from using it in other programs, such as Firefox. Please explain to me how this key combo works in IE7 because I can't figure it out.

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  • How do I cache RSS feeds in order not to miss entries on client side?

    - by Wakusei
    I'm using a client side RSS reader and turn on my PC at night. But some RSS feeds publish only a limited number of entries and old entries are removed from the feed. So sometimes I can miss entries. In order to avoid that, I want to cache feeds on some web service. Is there something like it? Although I know server side readers like Google Reader solve this problem, I still like client side readers.

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  • How to change the order of OS's on my boot screen on a dual boot setup?

    - by th3dude19
    I'm running a dual boot configuration on my laptop using Ubuntu 10.04b and Windows 7 Home Premium. Windows 7 was the original OS and I added a 'side by side' installation of Ubuntu. Ubuntu, however, shows up first on the list. I'd like to change this order and make Windows 7 first, followed by Ubunutu, then all of the recovery boots after that. Any help on how this is done?

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  • WCF DataContractSerializer Behavior

    - by sbanwart
    I'm seeing some unusual behavior when using the DataContractSerializer. I have defined a message contract like so: namespace MyNamespace.DataContracts { [MessageContract(WrapperName = "order", WrapperNamespace = @"http://example.com/v1/order")] public class MyOrder { [MessageBodyMember(Namespace = @"http://http://example.com/v1/order", Order = 1)] public MyStore store; [MessageBodyMember(Namespace = @"http://http://example.com/v1/order", Order = 2)] public MyOrderHeader orderHeader; [MessageBodyMember(Namespace = @"http://example.com/v1/order", Order = 3)] public List<MyPayment> payments; [MessageBodyMember(Namespace = @"http://example.com/v1/order", Order = 4)] public List<MyShipment> shipments; } . . I'm sending it an XML message that looks like this: <?xml version="1.0" encoding="utf-8"?> <order xmlns="http://example.com/v1/order> <store> ... </store> <orderHeader> ... </orderHeader> <payments> <payment> ... </payment> </payments> <shipments> <shipment> ... </shipment> </shipments> </order> My service deserializes this XML as expected. Inside my service, I'm using the DataContractSerializer to create an XML string and that's where things get weird. I'm using the serializer like this: DataContractSerializer serializer = new DataContractSerializer(typeof(MyOrder)); using (MemoryStream ms = new MemoryStream()) { serializer.WriteObject(ms, order); ms.Position = 0; StreamReader sr = new StreamReader(ms); string outputMessage = sr.ReadToEnd(); } Once this finishes, the outputMessage contains the following XML: <?xml version="1.0" encoding="utf-8"?> <MyOrder xmlns="http://example.com/v1/order" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"> <order> <store> ... </store> <orderHeader> ... </orderHeader> <payments> <payment> ... </payment> </payments> <shipments> <shipment> ... </shipment> </shipments> </order> </MyOrder> Needless to say, anything expecting to receive the original XML message will fail to parse this. So I guess I have two questions: Why is the DataContractSerializer adding the extra outer node to my XML output? Is there a way to stop it from doing this? Thanks.

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  • Does GC guarantee that cleared References are enqueued to ReferenceQueue in topological order?

    - by Dimitris Andreou
    Say there are two objects, A and B, and there is a pointer A.x --> B, and we create, say, WeakReferences to both A and B, with an associated ReferenceQueue. Assume that both A and B become unreachable. Intuitively B cannot be considered unreachable before A is. In such a case, do we somehow get a guarantee that the respective references will be enqueued in the intuitive (topological when there are no cycles) order in the ReferenceQueue? I.e. ref(A) before ref(B). I don't know - what if the GC marked a bunch of objects as unreachable, and then enqueued them in no particular order? I was reviewing Finalizer.java of guava, seeing this snippet: private void cleanUp(Reference<?> reference) throws ShutDown { ... if (reference == frqReference) { /* * The client no longer has a reference to the * FinalizableReferenceQueue. We can stop. */ throw new ShutDown(); } frqReference is a PhantomReference to the used ReferenceQueue, so if this is GC'ed, no Finalizable{Weak, Soft, Phantom}References can be alive, since they reference the queue. So they have to be GC'ed before the queue itself can be GC'ed - but still, do we get the guarantee that these references will be enqueued to the ReferenceQueue at the order they get "garbage collected" (as if they get GC'ed one by one)? The code implies that there is some kind of guarantee, otherwise unprocessed references could theoretically remain in the queue. Thanks

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  • delayed evaluation of code in subroutines - 5.8 vs. 5.10 and 5.12

    - by Brock
    This bit of code behaves differently under perl 5.8 than it does under perl 5.12: my $badcode = sub { 1 / 0 }; print "Made it past the bad code.\n"; [brock@chase tmp]$ /usr/bin/perl -v This is perl, v5.8.8 built for i486-linux-gnu-thread-multi [brock@chase tmp]$ /usr/bin/perl badcode.pl Illegal division by zero at badcode.pl line 1. [brock@chase tmp]$ /usr/local/bin/perl -v This is perl 5, version 12, subversion 0 (v5.12.0) built for i686-linux [brock@chase tmp]$ /usr/local/bin/perl badcode.pl Made it past the bad code. Under perl 5.10.1, it behaves as it does under 5.12: brock@laptop:/var/tmp$ perl -v This is perl, v5.10.1 (*) built for i486-linux-gnu-thread-multi brock@laptop:/var/tmp$ perl badcode.pl Made it past the bad code. I get the same results with a named subroutine, e.g. sub badcode { 1 / 0 } I don't see anything about this in the perl5100delta pod. Is this an undocumented change? A unintended side effect of some other change? (For the record, I think 5.10 and 5.12 are doing the Right Thing.)

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  • Specific complex array sorting

    - by TheDeadMedic
    Okay, a before; Array ( 'home' => array('order' => 1), 'about' => array(), 'folio' => array('order' => 2), 'folio/web' => array('order' => 2), 'folio/print' => array('order' => 1) 'contact' => array('order' => 2) ) And a desired after; Array ( 'home' => array('order' => 1), 'contact' => array('order' => 2), 'folio' => array('order' => 2), 'folio/print' => array('order' => 1), 'folio/web' => array('order' => 2), 'about' => array() ) I know, horrific (don't ask!) See how the slash in the key indicates children, and how the order is nested accordingly? And items without orders are simply shifted to the bottom. But also how multiple 'same level' items with the same order are merely sorted by key?

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  • Can ElementTree be told to preserve the order of attributes?

    - by dmckee
    I've written a fairly simple filter in python using ElementTree to munge the contexts of some xml files. And it works, more or less. But it reorders the attributes of various tags, and I'd like it to not do that. Does anyone know a switch I can throw to make it keep them in specified order? Context for this I'm working with and on a particle physics tool that has a complex, but oddly limited configuration system based on xml files. Among the many things setup that way are the paths to various static data files. These paths are hardcoded into the existing xml and there are no facilities for setting or varying them based on environment variables, and in our local installation they are necessarily in a different place. This isn't a disaster because the combined source- and build-control tool we're using allows us to shadow certain files with local copies. But even thought the data fields are static the xml isn't, so I've written a script for fixing the paths, but with the attribute rearrangement diffs between the local and master versions are harder to read than necessary. This is my first time taking ElementTree for a spin (and only my fifth or sixth python project) so maybe I'm just doing it wrong. Abstracted for simplicity the code looks like this: tree = elementtree.ElementTree.parse(inputfile) i = tree.getiterator() for e in i: e.text = filter(e.text) tree.write(outputfile) Reasonable or dumb? Related links: How can I get the order of an element attribute list using Python xml.sax? Preserve order of attributes when modifying with minidom

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  • On saving an new active record, in what order are the associated objects saved?

    - by Bryan
    In rails, when saving an active_record object, its associated objects will be saved as well. But has_one and has_many association have different order in saving objects. I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I expected that when team.save is called, team should be saved before its associated coach and players. I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid I figured out that team.save! saves objects in the following order: 1) players, 2) team, and 3) coach. This is why I got the error: When a player is saved, team doesn't yet have a id, so validates_presence_of :team_id fails in player. Can someone explain to me why objects are saved in this order? This seems not logical to me.

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  • How can I have sub-elements of a complex/mixed type with unrestricted order and count?

    - by mbmcavoy
    I am working with XML where some elements will contain text with additional markup. This is similar to this example at W3Schools. However, I need the markup tags to be able to appear in any order and possibly more than once. To modify their example for illustration: <letter> Dear Mr.<name>John Smith</name>. Your order <orderid>1032</orderid> will be shipped on <shipdate>2001-07-13</shipdate>. Thank you, <name>Bob Adams</name> </letter> None of the options presented by W3Schools (on the page following the linked example) allow this XML due to the second <name> element. Their explanation of the "indicators" and my testing are consistent. <xs:sequence> - violates the element order <xs:choice> - more than one kind of element is used. <xs:all> - maxOccurs is restricted to "1". This seems like it should be basic, after all, XHTML allows such things. How do I define my schema to allow this?

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  • Saving an active record, in what order are the associated objects saved?

    - by Bryan
    In rails, when saving an active_record object, its associated objects will be saved as well. But has_one and has_many association have different order in saving objects. I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I expected that when team.save is called, team should be saved before its associated coach and players. I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid I figured out that team.save! saves objects in the following order: 1) players, 2) team, and 3) coach. This is why I got the error: When a player is saved, team doesn't yet have a id, so validates_presence_of :team_id fails in player. Can someone explain to me why objects are saved in this order? This seems not logical to me.

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  • Can I force the auto-generated Linq-to-SQL classes to use an OUTER JOIN?

    - by Gary McGill
    Let's say I have an Order table which has a FirstSalesPersonId field and a SecondSalesPersonId field. Both of these are foreign keys that reference the SalesPerson table. For any given order, either one or two salespersons may be credited with the order. In other words, FirstSalesPersonId can never be NULL, but SecondSalesPersonId can be NULL. When I drop my Order and SalesPerson tables onto the "Linq to SQL Classes" design surface, the class builder spots the two FK relationships from the Order table to the SalesPerson table, and so the generated Order class has a SalesPerson field and a SalesPerson1 field (which I can rename to SalesPerson1 and SalesPerson2 to avoid confusion). Because I always want to have the salesperson data available whenever I process an order, I am using DataLoadOptions.LoadWith to specify that the two salesperson fields are populated when the order instance is populated, as follows: dataLoadOptions.LoadWith<Order>(o => o.SalesPerson1); dataLoadOptions.LoadWith<Order>(o => o.SalesPerson2); The problem I'm having is that Linq to SQL is using something like the following SQL to load an order: SELECT ... FROM Order O INNER JOIN SalesPerson SP1 ON SP1.salesPersonId = O.firstSalesPersonId INNER JOIN SalesPerson SP2 ON SP2.salesPersonId = O.secondSalesPersonId This would make sense if there were always two salesperson records, but because there is sometimes no second salesperson (secondSalesPersonId is NULL), the INNER JOIN causes the query to return no records in that case. What I effectively want here is to change the second INNER JOIN into a LEFT OUTER JOIN. Is there a way to do that through the UI for the class generator? If not, how else can I achieve this? (Note that because I'm using the generated classes almost exclusively, I'd rather not have something tacked on the side for this one case if I can avoid it).

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  • How do I enforce the order of qmake library dependencies?

    - by James Oltmans
    I'm getting a lot of errors because qmake is improperly ordering the boost libraries I'm using. Here's what .pro file looks like QT += core gui TARGET = MyTarget TEMPLATE = app CONFIG += no_keywords \ link_pkgconfig SOURCES += file1.cpp \ file2.cpp \ file3.cpp PKGCONFIG += my_package \ sqlite3 LIBS += -lsqlite3 \ -lboost_signals \ -lboost_date_time HEADERS += file1.h\ file2.h\ file3.h FORMS += mainwindow.ui RESOURCES += Resources/resources.qrc This produces the following command: g++ -Wl,-O1 -o MyTarget file1.o file2.o file3.o moc_mainwindow.o -L/usr/lib/x86_64-linux-gnu -lboost_signals -lboost_date_time -L/usr/local/lib -lmylib1 -lmylib2 -lsqlite3 -lQtGui -lQtCore Note: mylib1 and mylib2 are statically compiled by another project, placed in /usr/local/lib with an appropriate pkg-config .pc file pointing there. The .pro file references them via my_package in PKGCONFIG. The problem is not with pkg-config's output but with Qt's ordering. Here's the .pc file: prefix=/usr/local exec_prefix=${prefix} libdir=${exec_prefix}/lib includedir=${prefix}/include Name: my_package Description: My component package Version: 0.1 URL: http://example.com Libs: -L${libdir} -lmylib1 -lmylib2 Cflags: -I${includedir}/my_package/ The linking stage fails spectacularly as mylib1 and mylib2 come up with a lot of undefined references to boost libraries that both the app and mylib1 and mylib2 are using. We have another build method using scons and it properly orders things for the linker. It's build command order is below. g++ -o MyTarget file1.o file2.o file3.o moc_mainwindow.o -L/usr/local/lib -lmylib1 -lmylib2 -lsqlite3 -lboost_signals -lboost_date_time -lQtGui -lQtCore Note that the principle difference is the order of the boost libs. Scons puts them at the end just before QtGui and QtCore while qmake puts them first. The other differences in the compile commands are unimportant as I have hand modified the qmake produced make file and the simple reordering fixed the problem. So my question is, how do I enforce the right order in my .pro file despite what qmake thinks they should be?

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  • Having to insert a record, then update the same record warrants 1:1 relationship design?

    - by dianovich
    Let's say an Order has many Line items and we're storing the total cost of an order (based on the sum of prices on order lines) in the orders table. -------------- orders -------------- id ref total_cost -------------- -------------- lines -------------- id order_id price -------------- In a simple application, the order and line are created during the same step of the checkout process. So this means INSERT INTO orders .... -- Get ID of inserted order record INSERT into lines VALUES(null, order_id, ...), ... where we get the order ID after creating the order record. The problem I'm having is trying to figure out the best way to store the total cost of an order. I don't want to have to create an order create lines on an order calculate cost on order based on lines then update record created in 1. in orders table This would mean a nullable total_cost field on orders for starters... My solution thus far is to have an order_totals table with a 1:1 relationship to the orders table. But I think it's redundant. Ideally, since everything required to calculate total costs (lines on an order) is in the database, I would work out the value every time I need it, but this is very expensive. What are your thoughts?

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  • Is dynamic evaluation of xpath variable string possible using .net 2.0 xslt implementation?

    - by Crocked
    Hi, I'm trying to evaluate an xpath varable I'm building dynamically based on the position of the node. I can create the xpath string in a variable but when I select the value of this just get the string and not the node set I need. I use the following to create the xpath <xsl:variable name="xpathstring" select="normalize-space(concat(&quot;//anAttribute[@key='pos&quot;,position(),&quot;']&quot;))"/> and try to output the value with the following. <xsl:value-of select="$xpathstring"/> If I execute the xpath in my debugger I get the nodeset but in my xml output only get the xpath string which looks like this //anAttribute[@key='pos1'] I had a look at exslt dyn:evaluate which seems to enable this but this seems to be only supported by certain processors and doesn't provide a standalone implementation or at least as far as I could see (currently using the standard .net 2.0 xslt whihc is only xslt 1.0 as far as I recall) Is there anyway to handle this without changing processor? Kind Regards, Crocked

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