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• recursive enumeration of integer subsets?

  - by KDaker

  I have an NSArray of NSNumbers with integer values such as [1,10,3]. I want to get the sum of all the possible subsets of these numbers. For example for 1,10 and 3 i would get: 1, 10, 3, 1+10=11, 1+3=4, 10+3=13, 1+10+3=14 there are 2^n possible combinations. I understand the math of it but im having difficulties putting this into code. so how can i put this into a method that would take the initial array of numbers and return an array with all the sums of the subsets? e.g -(NSArray *) getSums:(NSArray *)numbers; I understand that the results grow exponentially but im going to be using it for small sets of numbers.

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• PHP query for totals of products for last six months

  - by user2260925

  I need to get the figures for the last six months from my orders table. The table has the following fields: qty, product, price, code, The format of the report must be as follows: Month: Jan Feb Mar Apr May June Product1 7 5 4 6 8 9 Product2 8 3 1 4 7 7 Product3 5 4 1 7 7 6 My current code gets the figures for one month only: "SELECT product,building, SUM(qty) AS 'month1' FROM sh_orders WHERE MONTH(order_date) = MONTH(CURDATE()) GROUP BY product"; The code to show it is: echo " <td> ". $row['product']. "</td> <td> ". $row['month1']. "</td>; Any help is greatly appreciated.

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• Writing array to text file

  - by user3661876

  I have an array, but it won't write each index to the text file. Instead it is only writing the last index and the other indexes are not appearing. Can anyone help me to get the entire array printed to the text file? static void solve(int k) { if (k == N) // We placed N-1 queens (0 included), problem solved! { // Solution found! using (StreamWriter sw = new StreamWriter("names.txt")) { Console.Write("Solution: "); for (int i = 0; i < N; i++) { Console.Write(position[i] + " "); foreach (int s in position[i].ToString()) { string list = position[i].ToString(); sw.Write(list + " "); } } Console.WriteLine(); sum += 1; } }

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• C Different answers for a variable when running 'Debug' and 'Start without debug'

  - by Craz

  I keep getting this weird output from my code everytime I use the 'start without degugging' (ctrl-F5) as opposed to normal 'debug' (F5). When I try to find the following value of norm_differnece in debug (pressing F5) mode, it gives me the correct answer for norm_difference normdifference = 1.000000 but in 'start without debugging' (pressing ctrl-f5) the wrong output normdifference = 1456816083547664100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.000000 The following is a segment of code which is gives the output Note: X[] = is a array of stored DOUBLE values for(i=0;i<n;i++){ sum_difference += (pow((X[i*n]-X[i]),2)); } norm_difference = sqrt(norm_difference); for(i=0;i<n;i++){ sum_norm_1 += pow(X[i],2); } norm_1 = sqrt(norm_1); //Take square root of the sum of squares for the row printf("normdifference = %f \n norm_1 = %f \n",norm_difference,norm_1);

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• summing up excel files in matlab

  - by AP

  Is there a easy good way to sum up various excel files in matlab? what i really want is similar to dos command type file*.xls sumfile.xls I have from 10-100 excel files with similar file name formats excet the date XXXXX_2010_03_03.xls, XXXXX_2010_03_03.xls and so on..... Is there a command to copy the files one after other. All files are of diff length so i cannot know the position of the rows after each file. I would like to have them copied in same sheet of excel. Thanks

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• How can I improve the performance of this algorithm

  - by Justin

  // Checks whether the array contains two elements whose sum is s. // Input: A list of numbers and an integer s // Output: return True if the answer is yes, else return False public static boolean calvalue (int[] numbers, int s){ for (int i=0; i< numbers.length; i++){ for (int j=i+1; j<numbers.length;j++){ if (numbers[i] < s){ if (numbers[i]+numbers[j] == s){ return true; } } } } return false; }

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• C++: how serialize/deserialize objects without any library?

  - by Winte Winte

  I try to understand how serializing/deserializing works in c++, so I want to do that without any libs. But I really stuck with that. I start with simple objects but when I try to deserilize a vector I understand that I can't get a vector without if I don't write it size before. Moreover, I don't know which format of file I should choose because if digits will be existed before size of vector I haven't chance to read it right. However it is only the vector but I also want to do that with classes and map container. My task is serialize/deserialize a objects as this: PersonInfo { unsigned int age_; string name_; enum { undef, man, woman } sex_; } Person : PersonInfo { vector<Person> children_; map<string, PersonInfo> addrBook_; } Currently I know how to serialize simple objects in way as this: vector<PersonInfo> vecPersonInfo; vecPersonInfo.push_back(*personInfo); vecPersonInfo.push_back(*oneMorePersonInfo); ofstream file("file", ios::out | ios::binary); if (!file) { cout<<"can not open file"; } else { vector<PersonInfo>::const_iterator iterator = vecPersonInfo.begin(); for (; iterator != vecPersonInfo.end(); iterator++) { file<<*iterator; } Could you please suggest how I can do this for this conplex object or a good tutorial that explain it clearly?

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• What is this kind of chaining in C# called?

  - by Thinking

  Can you please tell me what kind of construct in C# is this. Code Golf: Numeric equivalent of an Excel column name C.WriteLine(C.ReadLine() .Reverse() .Select((c, i) => (c - 64) * System.Math.Pow(26, i)) .Sum()); Though I am new to C# (only two months exp so far), but since the time I have joined a C# team, I have never seen this kind of chaining. It really attracted me and I want to learn more about it. Please give some insight about this.

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• How do I exclude outliers from an aggregate query?

  - by Margaret

  I'm creating a report comparing total time and volume across units. Here a simplification of the query I'm using at the moment: SELECT m.Unit, COUNT(*) AS Count, SUM(m.TimeInMinutes) AS TotalTime FROM main_table m WHERE m.unit <> '' AND m.TimeInMinutes > 0 GROUP BY m.Unit HAVING COUNT(*) > 15 However, I have been told that I need to exclude cases where the row's time is in the highest or lowest 5% to try and get rid of a few wacky outliers. (As in, remove the rows before the aggregates are applied.) How do I do that?

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• What is most efficient way of setting row to zeros for a sparce scipy matrix?

  - by Alex Reinking

  I'm trying to convert the following MATLAB code to Python and am having trouble finding a solution that works in any reasonable amount of time. M = diag(sum(a)) - a; where = vertcat(in, out); M(where,:) = 0; M(where,where) = 1; Here, a is a sparse matrix and where is a vector (as are in/out). The solution I have using Python is: M = scipy.sparse.diags([degs], [0]) - A where = numpy.hstack((inVs, outVs)).astype(int) M = scipy.sparse.lil_matrix(M) M[where, :] = 0 # This is the slowest line M[where, where] = 1 M = scipy.sparse.csc_matrix(M) But since A is 334863x334863, this takes like three minutes. If anyone has any suggestions on how to make this faster, please contribute them! For comparison, MATLAB does this same step imperceptibly fast. Thanks!

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• Oracle Group By Issue

  - by m_oLogin

  Hello community, I am strugling with what seems an easy problem to tackle (at least for me in MySQL / SqlServer!) I'll simplify the problem. Let's say I have the following table: Table VOTE ID ID_IDEA DATE_VOTE with ID_IDEA FK(IDEA.ID) 1 3 10/10/10 2 0 09/09/10 3 3 08/08/10 4 3 11/11/10 5 0 06/06/10 6 1 05/05/10 I'm trying to find the latest votes given for each individual idea, meaning I want to return only rows with ID 4, 2 and 6. It seems with Oracle that you can't use GROUP BY without using a function like SUM(), AVG, etc. I'm a bit confused about how it's supposed to work. Please advise, Thanks.

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• "...redeclared as different kind of symbol"?

  - by CodeNewb

  #include <stdio.h> #include <math.h> double integrateF(double low, double high) { double low = 0; double high = 20; double delta_x=0; double x, ans; double s = 1/2*exp((-x*x)/2); for(x=low;x<=high;x++) delta_x = x+delta_x; ans = delta_x*s; return ans; } It says that low and high are "redeclared as different type of symbol" and I don't know what that means. Basically, all I'm doing here (READ: trying) is integrating from low (which I set to 0) to high (20) to find the Riemann sum. The for loop looks kinda trippy too...I'm so lost.

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• PHP form validation function

  - by Barbs

  I am currently writing some PHP form validation (I have already validated clientside) and have some repetitive code that I think would work well in a nice little PHP function. However I have having trouble getting it to work. I'm sure it's just a matter of syntax but I just can't nail it down. Any help appreciated. //Validate phone number field to ensure 8 digits, no spaces. if(0 === preg_match("/^[0-9]{8}$/",$_POST['Phone']) { $errors['Phone'] = "Incorrect format for 'Phone'"; } if(!$errors) { //Do some stuff here.... } I found that I was writing the validation code a lot and I could save some time and some lines of code by creating a function. //Validate Function function validate($regex,$index,$message) { if(0 === preg_match($regex,$_POST[$index],$message) { $errors[$index] = $message; } And call it like so.... validate("/^[0-9]{8}$/","Phone","Incorrect format for Phone"); Can anyone see why this wouldn't work? Note I have disabled the client side validation while I work on this to try to trigger the error, so the value I am sending for 'Phone' is invalid.

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• In Perl, how to match several prefixes

  - by xorsyst

  I have 2 input files. One is a list of prefix and lengths, like this: 101xxx 102xxx 30xx 31xx (where x is any number) And another is a list of numbers. I want to iterate through the second file, matching each number against any of the prefix/lengths. This is fairly easy. I build a list of regexps: my @regexps = ('101...', '102...', '30..', '31..'); Then: foreach my $regexp (@regexps) { if (/$regexp/) { # do something But, as you can guess, this is slow for a long list. I could convert this to a single regexp: my $super_regexp = '101...|102...|30..|31..'; ...but, what I need is to know which regexp matched the item, and what the ..s matched. I tried this: my $catching_regexp = '(101)(...)|(102)(...)|(30)(..)|(31)(..)'; but then I don't know whether to look in $1, $3, %5 or $7. Any ideas? How can I match against any of these prefix/lengths and know which prefix, and what the remaining digits where?

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• Redirect all access requests to a domain and subdomain(s) except from specific IP address? [closed]

  - by Christopher

  This is a self-answered question... After much wrangling I found the magic combination of mod_rewrite rules so I'm posting here. My scenario is that I have two domains - domain1.com and domain2.com - both of which are currently serving identical content (by way of a global 301 redirect from domain1 to domain2). Domain1 was then chosen to be repurposed to be a 'portal' domain - with a corporate CMS-based site leading off from the front page, and the existing 'retail' domain (domain2) left to serve the main web site. In addition, a staging subdomain was created on domain1 in order to prepare the new corporate site without impinging on the root domain's existing operation. I contemplated just rewriting all requests to domain2 and setting up the new corporate site 'behind the scenes' without using a staging domain, but I usually use subdomains when setting up new sites. Finally, I required access to the 'actual' contents of the domains and subdomains - i.e., to not be redirected like all other visitors - in order that I can develop the new site and test it in the staging environment on the live server, as I'm not using a separate development webserver in this case. I also have another test subdomain on domain1 which needed to be preserved. The way I eventually set it up was as follows: (10.2.2.1 would be my home WAN IP) .htaccess in root of domain1 RewriteEngine On RewriteCond %{REMOTE_ADDR} !^10\.2\.2\.1 RewriteCond %{HTTP_HOST} !^staging.domain1.com$ [NC] RewriteCond %{HTTP_HOST} !^staging2.domain1.com$ [NC] RewriteRule ^(.*)$ http://domain2.com/$1 [R=301] .htaccess in staging subdomain on domain1: RewriteEngine On RewriteCond %{REMOTE_ADDR} !^10\.2\.2\.1 RewriteCond %{HTTP_HOST} ^staging.revolver.coop$ [NC] RewriteRule ^(.*)$ http://domain2.com/$1 [R=301,L] The multiple .htaccess files and multiple rulesets require more processing overhead and longer iteration as the visitor is potentially redirected twice, however I find it to be a more granular method of control as I can selectively allow more than one IP address access to individual staging subdomain(s) without automatically granting them access to everything else. It also keeps the rulesets fairly simple and easy to read. (or re-interpret, because I'm always forgetting how I put rules together!) If anybody can suggest a more efficient way of merging all these rules and conditions into just one main ruleset in the root of domain1, please post! I'm always keen to learn, this post is more my attempt to preserve this information for those who are looking to redirect entire domains for all visitors except themselves (for design/testing purposes) and not just denying specific file access for maintenance mode (there are many good examples of simple mod_rewrite rules for 'maintenance mode' style operation easily findable via Google). You can also extend the IP address detection - firstly by using wildcards ^10\.2\.2\..*: the last octet's \..* denotes the usual "." and then "zero or more arbitrary characters", signified by the .* - so you can specify specific ranges of IPs in a subnet or entire subnets if you wish. You can also use square brackets: ^10\.2\.[1-255]\.[120-140]; ^10\.2\.[1-9]?[0-9]\.; ^10\.2\.1[0-1][0-9]\. etc. The third way, if you wish to specify multiple discrete IP addresses, is to bracket them in the style of ^(1.1.1.1|2.2.2.2|3.3.3.3)$, and you can of course use square brackets to substitute octets or single digits again. NB: if you're using individual RewriteCond lines to specify multiple IPs / ranges, make sure to put [OR] at the end of each one otherwise mod_rewrite will interpret as "if IP address matches 1.1.1.1 AND if IP address matches 2.2.2.2... which is of course impossible! However as far as I'm aware this isn't necessary if you're using the ! negator to specify "and is not...". Kudos also to SE: this older question also came in useful when I was verifying my own knowledge prior to my futzing around with code. This page was helpful, as were the various other links posted below (can't hyperlink them all due to spam protection... other regex checkers are available). The AddedBytes cheat sheet's useful to pin up on your wall. Other referenced URLs: internetofficer.com/seo-tool/regex-tester/ fantomaster.com/faarticles/rewritingurls.txt internetofficer.com/seo-tool/regex-tester/ addedbytes.com/cheat-sheets/mod_rewrite-cheat-sheet/

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• Defining Discovery: Core Concepts

  - by Joe Lamantia

  Discovery tools have had a referencable working definition since at least 2001, when Ben Shneiderman published 'Inventing Discovery Tools: Combining Information Visualization with Data Mining'.  Dr. Shneiderman suggested the combination of the two distinct fields of data mining and information visualization could manifest as new category of tools for discovery, an understanding that remains essentially unaltered over ten years later.  An industry analyst report titled Visual Discovery Tools: Market Segmentation and Product Positioning from March of this year, for example, reads, "Visual discovery tools are designed for visual data exploration, analysis and lightweight data mining." Tools should follow from the activities people undertake (a foundational tenet of activity centered design), however, and Dr. Shneiderman does not in fact describe or define discovery activity or capability. As I read it, discovery is assumed to be the implied sum of the separate fields of visualization and data mining as they were then understood.  As a working definition that catalyzes a field of product prototyping, it's adequate in the short term.  In the long term, it makes the boundaries of discovery both derived and temporary, and leaves a substantial gap in the landscape of core concepts around discovery, making consensus on the nature of most aspects of discovery difficult or impossible to reach.  I think this definitional gap is a major reason that discovery is still an ambiguous product landscape. To help close that gap, I'm suggesting a few definitions of four core aspects of discovery.  These come out of our sustained research into discovery needs and practices, and have the goal of clarifying the relationship between discvoery and other analytical categories.  They are suggested, but should be internally coherent and consistent.   Discovery activity is: "Purposeful sense making activity that intends to arrive at new insights and understanding through exploration and analysis (and for these we have specific defintions as well) of all types and sources of data." Discovery capability is: "The ability of people and organizations to purposefully realize valuable insights that address the full spectrum of business questions and problems by engaging effectively with all types and sources of data." Discovery tools: "Enhance individual and organizational ability to realize novel insights by augmenting and accelerating human sense making to allow engagement with all types of data at all useful scales." Discovery environments: "Enable organizations to undertake effective discovery efforts for all business purposes and perspectives, in an empirical and cooperative fashion." Note: applicability to a world of Big data is assumed - thus the refs to all scales / types / sources - rather than stated explicitly.  I like that Big Data doesn't have to be written into this core set of definitions, b/c I think it's a transitional label - the new version of Web 2.0 - and goes away over time. References and Resources: Inventing Discovery Tools Visual Discovery Tools: Market Segmentation and Product Positioning Logic versus usage: the case for activity-centered design A Taxonomy of Enterprise Search and Discovery

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• July, the 31 Days of SQL Server DMO’s – Day 21 (sys.dm_db_partition_stats)

  - by Tamarick Hill

  The sys.dm_db_partition_stats DMV returns page count and row count information for each table or index within your database. Lets have a quick look at this DMV so we can review some of the results. **NOTE: I am going to create an ‘ObjectName’ column in our result set so that we can more easily identify tables. SELECT object_name(object_id) ObjectName, * FROM sys.dm_db_partition_stats As stated above, the first column in our result set is an Object name based on the object_id column of this result set. The partition_id column refers to the partition_id of the index in question. Each index will have at least 1 unique partition_id and will have more depending on if the object has been partitioned. The index_id column relates back to the sys.indexes table and uniquely identifies an index on a given object. A value of 0 (zero) in this column would indicate the object is a HEAP and a value of 1 (one) would signify the Clustered Index. Next is the partition_number which would signify the number of the partition for a particular object_id. Since none of my tables in my result set have been partitioned, they all display 1 for the partition_number. Next we have the in_row_data_page_count which tells us the number of data pages used to store in-row data for a given index. The in_row_used_page_count is the number of pages used to store and manage the in-row data. If we look at the first row in the result set, we will see we have 700 for this column and 680 for the previous. This means that just to manage the data (not store it) is requiring 20 pages. The next column in_row_reserved_page_count is how many pages have been reserved, regardless if they are being used or not. The next 2 columns are used for storing LOB (Large Object) data which could be text, image, varchar(max), or varbinary(max) columns. The next two columns, row_overflow, represent pages used for data that exceed the 8,060 byte row size limit for the in-row data pages. The next columns used_page_count and reserved_page_count represent the sum of the in_row, lob, and row_overflow columns discussed earlier. Lastly is a row_count column which displays the number of rows that are in a particular index. This DMV is a very powerful resource for identifying page and row count information. By knowing the page counts for indexes within your database, you are able to easily calculate the size of indexes. For more information on this DMV, please see the below Books Online link: http://msdn.microsoft.com/en-us/library/ms187737.aspx Follow me on Twitter @PrimeTimeDBA

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• DBCC MEMUSAGE in 2005/8 ?

  - by steveh99999

  I used to like using undocumented command DBCC MEMUSAGE in SQL 2000 to see which tables were using space in SQL data cache. In SQL 2005, this command is not longer present. Instead a DMV – sys.dm_os_buffer_descriptors – can be used to display data cache contents,  but this doesn’t quite give you the same output as DBCC MEMUSAGE. I’m also aware that you can use Quest’s spotlight tool to view a summary of data cache contents. Using  this post by Umachandar Jayachandran  of Microsoft, I was able to create the following equivalent for SQL 2005/8. I’ve wrapped Umachandar’s original query in a CTE to produce summary information :- ;WITH memusage_CTE AS (SELECT bd.database_id, bd.file_id, bd.page_id, bd.page_type , COALESCE(p1.object_id, p2.object_id) AS object_id , COALESCE(p1.index_id, p2.index_id) AS index_id , bd.row_count, bd.free_space_in_bytes, CONVERT(TINYINT,bd.is_modified) AS 'DirtyPage' FROM sys.dm_os_buffer_descriptors AS bd JOIN sys.allocation_units AS au ON au.allocation_unit_id = bd.allocation_unit_id OUTER APPLY ( SELECT TOP(1) p.object_id, p.index_id FROM sys.partitions AS p WHERE p.hobt_id = au.container_id AND au.type IN (1, 3) ) AS p1 OUTER APPLY ( SELECT TOP(1) p.object_id, p.index_id FROM sys.partitions AS p WHERE p.partition_id = au.container_id AND au.type = 2 ) AS p2 WHERE  bd.database_id = DB_ID() AND bd.page_type IN ('DATA_PAGE', 'INDEX_PAGE') ) SELECT TOP 20 DB_NAME(database_id) AS 'Database',OBJECT_NAME(object_id,database_id) AS 'Table Name', index_id,COUNT(*) AS 'Pages in Cache', SUM(dirtyPage) AS 'Dirty Pages' FROM memusage_CTE GROUP BY database_id, object_id, index_id ORDER BY COUNT(*) DESC I’m not 100% happy with the results of the above query however… I’ve noticed that on a busy BizTalk messageBox database  it will return information on pages that contain GHOST rows – . ie where data has already been deleted but has yet to be cleaned-up by a background process – I’m need to investigate further why cache on this server apparently contains so much GHOST data… For more information on the background ghost cleanup process, see this article by Paul Randall. However, I think the results of this query should still be of interest to a DBA. I have another post to come shortly regarding an example I encountered where this information proved useful to me… I notice in SQL 2008, sys.dm_os_buffer_descriptors gained an extra column – numa_mode – I’m interested to see how this is populated and how useful this column can be on a NUMA-enabled system. I’m assuming in theory you could use this column to help analyse how your tables are spread across Numa-enabled data-cache ?

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• Delegates in c#

  - by Jalpesh P. Vadgama

  I have used delegates in my programming since C# 2.0. But I have seen there are lots of confusion going on with delegates so I have decided to blog about it. In this blog I will explain about delegate basics and use of delegates in C#. What is delegate? We can say a delegate is a type safe function pointer which holds methods reference in object. As per MSDN it's a type that references to a method. So you can assign more than one methods to delegates with same parameter and same return type. Following is syntax for the delegate public delegate int Calculate(int a, int b); Here you can see the we have defined the delegate with two int parameter and integer parameter as return parameter. Now any method that matches this parameter can be assigned to above delegates. To understand the functionality of delegates let’s take a following simple example. using System; namespace Delegates { class Program { public delegate int CalculateNumber(int a, int b); static void Main(string[] args) { int a = 5; int b = 5; CalculateNumber addNumber = new CalculateNumber(AddNumber); Console.WriteLine(addNumber(5, 6)); Console.ReadLine(); } public static int AddNumber(int a, int b) { return a + b; } } } Here in the above code you can see that I have created a object of CalculateNumber delegate and I have assigned the AddNumber static method to it. Where you can see in ‘AddNumber’ static method will just return a sum of two numbers. After that I am calling method with the help of the delegates and printing out put to the console application. Now let’s run the application and following is the output as expected. That’s it. You can see the out put of delegates after adding a number. This delegates can be used in variety of scenarios. Like in web application we can use it to update one controls properties from another control’s action. Same you can also call a delegates whens some UI interaction done like button clicked. Hope you liked it. Stay tuned for more. In next post I am going to explain about multicast delegates. Till then happy programming.

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• Tuxedo Load Balancing

  - by Todd Little

  A question I often receive is how does Tuxedo perform load balancing.  This is often asked by customers that see an imbalance in the number of requests handled by servers offering a specific service. First of all let me say that Tuxedo really does load or request optimization instead of load balancing.  What I mean by that is that Tuxedo doesn't attempt to ensure that all servers offering a specific service get the same number of requests, but instead attempts to ensure that requests are processed in the least amount of time.   Simple round robin "load balancing" can be employed to ensure that all servers for a particular service are given the same number of requests.  But the question I ask is, "to what benefit"?  Instead Tuxedo scans the queues (which may or may not correspond to servers based upon SSSQ - Single Server Single Queue or MSSQ - Multiple Server Single Queue) to determine on which queue a request should be placed.  The scan is always performed in the same order and during the scan if a queue is empty the request is immediately placed on that queue and request routing is done.  However, should all the queues be busy, meaning that requests are currently being processed, Tuxedo chooses the queue with the least amount of "work" queued to it where work is the sum of all the requests queued weighted by their "load" value as defined in the UBBCONFIG file.  What this means is that under light loads, only the first few queues (servers) process all the requests as an empty queue is often found before reaching the end of the scan.  Thus the first few servers in the queue handle most of the requests.  While this sounds non-optimal, in fact it capitalizes on the underlying operating systems and hardware behavior to produce the best possible performance.  Round Robin scheduling would spread the requests across all the available servers and thus require all of them to be in memory, and likely not share much in the way of hardware or memory caches.  Tuxedo's system maximizes the various caches and thus optimizes overall performance.  Hopefully this makes sense and now explains why you may see a few servers handling most of the requests.  Under heavy load, meaning enough load to keep all servers that can handle a request busy, you should see a relatively equal number of requests processed.  Next post I'll try and cover how this applies to servers in a clustered (MP) environment because the load balancing there is a little more complicated. Regards,Todd LittleOracle Tuxedo Chief Architect

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• Unit testing in Django

  - by acjohnson55

  I'm really struggling to write effective unit tests for a large Django project. I have reasonably good test coverage, but I've come to realize that the tests I've been writing are definitely integration/acceptance tests, not unit tests at all, and I have critical portions of my application that are not being tested effectively. I want to fix this ASAP. Here's my problem. My schema is deeply relational, and heavily time-oriented, giving my model object high internal coupling and lots of state. Many of my model methods query based on time intervals, and I've got a lot of auto_now_add going on in timestamped fields. So take a method that looks like this for example: def summary(self, startTime=None, endTime=None): # ... logic to assign a proper start and end time # if none was provided, probably using datetime.now() objects = self.related_model_set.manager_method.filter(...) return sum(object.key_method(startTime, endTime) for object in objects) How does one approach testing something like this? Here's where I am so far. It occurs to me that the unit testing objective should be given some mocked behavior by key_method on its arguments, is summary correctly filtering/aggregating to produce a correct result? Mocking datetime.now() is straightforward enough, but how can I mock out the rest of the behavior? I could use fixtures, but I've heard pros and cons of using fixtures for building my data (poor maintainability being a con that hits home for me). I could also setup my data through the ORM, but that can be limiting, because then I have to create related objects as well. And the ORM doesn't let you mess with auto_now_add fields manually. Mocking the ORM is another option, but not only is it tricky to mock deeply nested ORM methods, but the logic in the ORM code gets mocked out of the test, and mocking seems to make the test really dependent on the internals and dependencies of the function-under-test. The toughest nuts to crack seem to be the functions like this, that sit on a few layers of models and lower-level functions and are very dependent on the time, even though these functions may not be super complicated. My overall problem is that no matter how I seem to slice it, my tests are looking way more complex than the functions they are testing.

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• Book review: Peopleware: Productive Projects and Teams

  - by DigiMortal

     Peopleware by Tom DeMarco and Timothy Lister is golden classic book that can be considered as mandatory reading for software project managers, team leads, higher level management and board members of software companies. If you make decisions about people then you cannot miss this book. If you are already good on managing developers then this book can make you even better – you will learn new stuff about successful development teams for sure. Why peopleware? Peopleware gives you very good hints about how to build up working environment for project teams where people can really do their work. Book also covers team building topics that are also important reading. As software developer I found practically all points in this book to be accurate and valid. Many times I have found my self thinking about same things and Peopleware made me more confident about my opinions. Peopleware covers also time management and planning topics that help you do way better job on using developers time effectively by minimizing the amount of interruptions by phone calls, pointless meetings and i-want-to-know-what-are-you-doing-right-now questions by managers who doesn’t write code anyway. I think if you follow suggestions given by Peopleware your developers are very happy. I suggest you to also read another great book – Death March by Edward Yourdon. Death March describes you effectively what happens when good advices given by Peopleware are totally ignored or worse yet – people are treated exactly opposite way. I consider also Death March as golden classics and I strongly recommend you to read this book too. Table of Contents Acknowledgments Preface to the Second Edition Preface to the First Edition Part 1: Managing the Human Resource Chapter 1: Somewhere Today, a Project Is Failing Chapter 2: Make a Cheeseburger, Sell a Cheeseburger Chapter 3: Vienna Waits for You Chapter 4: Quality-If Time Permits Chapter 5: Parkinson's Law Revisited Chapter 6: Laetrile Part II: The Office Environment Chapter 7: The Furniture Police Chapter 8: "You Never Get Anything Done Around Here Between 9 and 5" Chapter 9: Saving Money on Space Intermezzo: Productivity Measurement and Unidentified Flying Objects Chapter 10: Brain Time Versus Body Time Chapter 11: The Telephone Chapter 12: Bring Back the Door Chapter 13: Taking Umbrella Steps Part III: The Right People Chapter 14: The Hornblower Factor Chapter 15: Hiring a Juggler Chapter 16: Happy to Be Here Chapter 17: The Self-Healing System Part IV: Growing Productive Teams Chapter 18: The Whole Is Greater Than the Sum of the Parts Chapter 19: The Black Team Chapter 20: Teamicide Chapter 21: A Spaghetti Dinner Chapter 22: Open Kimono Chapter 23: Chemistry for Team Formation Part V: It't Supposed to Be Fun to Work Here Chapter 24: Chaos and Order Chapter 25: Free Electrons Chapter 26: Holgar Dansk Part VI: Son of Peopleware Chapter 27: Teamicide, Revisited Chapter 28: Competition Chapter 29: Process Improvement Programs Chapter 30: Making Change Possible Chapter 31: Human Capital Chapter 32:Organizational Learning Chapter 33: The Ultimate Management Sin Is Chapter 34: The Making of Community Notes Bibliography Index About the Authors

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• A strong component keeps everything together

  - by Justin Paul-Oracle

  Most of the times you implement a WebCenter Content based system, you require some sort of customization. Sometimes these customizations need a Java class or two, or libraries (for example, the JavaMail API), or Database Objects (like new tables, views, indexes, etc). I have seen that libraries and Database Objects are usually put in place using manual steps. This means that the library jar files are copied to one of the common classes directory (set in the Content CLASSPATH variable) and/or the database scripts are executed manually. I have also seen people place the custom Java classes in the common classes directory. While this may seem like an easy solution, think about a scenario where you need to disable or uninstall the component or if you have to upgrade or migrate the system. You have to keep these manual steps documented and execute them every time you encounter the above scenarios. It is very common that some of these manual steps are missed when you have multiple teams and people working on the system. Here are a few points to ponder upon: Place all your custom Java classes within your component. Create a new directory, say ${COMPONENT_DIR}/classes, and place your code there. You can choose to bundle all your classes into a jar or you can place the entire class directory structure. Add a path entry to the Build Settings so that it is bundled with the component when you build it. You also need to update the Custom Class Path and the Custom Class Path Load Order under the Advanced Build Settings. This will ensure that the system CLASSPATH is updated to add this new directory. Create a new component for any new library that you want to add. Add the appropriate path entries to the Build Settings so that it is bundled with the component when you build it. You also need to update the Custom Class Path, Custom Class Path Load Order and/or the Custom Library Path under the Advanced Build Settings. Enter a comma separated list of features that this component will provide. When you create other components that will use the features exposed by this component, make sure that you specify a dependency to this library component by specifying the comma separated list of features in the Advanced Build Settings. The component wizard allows you to create custom install/uninstall Java code. The wizard will create a install filter class when you check the “Has Install” checkbox on the “Install/Uninstall Settings” tab. Consider using this filter class to create database objects when you install the component and drop the objects when you uninstall the component. If you do a lot of custom component development, consider creating a install/uninstall Java class, which can execute queries defined within the component. To sum up, whenever you write a new custom component, make sure that you bundle everything within the component.

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• Playing with F#

  - by mroberts

  Project Euler is a awesome site.   When working with a new language it can be tricky to find problems that need solving, that are more complex than "Hello World" and simpler than a full blown application. Project Euler gives use just that, cool and thought provoking problems that usually don't take days to solve.  I've solved a number of questions with C# and some with Java.  BTW, I used Java because it had BigInteger support before .Net. A couple weeks ago, back when winter had a firm grip on Columbus, OH, I began playing (researching) with F#.  I began with Problem #1 from Project Euler.  I started by looking at my solution in C#. Here is my solution in C#. 1: using System; 2: using System.Collections.Generic; 3:   4: namespace Problem001 5: { 6: class Program 7: { 8: static void Main(string[] args) 9: { 10: List<int> values = new List<int>(); 11:   12: for (int i = 1; i < 1000; i++) 13: { 14: if (i % 3 == 0 || i % 5 == 0) 15: values.Add(i); 16: } 17: int total = 0; 18:   19: values.ForEach(v => total += v); 20:   21: Console.WriteLine(total); 22: Console.ReadKey(); 23: } 24: } 25: }   Now, after much tweaking and learning, here is my solution in F#.   1: open System 2:   3: let calc n = 4: [1..n] 5: |> List.map (fun x -> if (x % 3 = 0 || x % 5 = 0) then x else 0) 6: |> List.sum 7:   8: let main() = 9: calc 999 10: |> printfn "result = %d" 11: Console.ReadKey(true) |> ignore 12:   13: main() Just this little example highlights some cool things about F#. Type inference. F# infers the type of a value.  In the C# code above we declare a number of variables, the list, and a couple ints.  F# does not require this, it infers the calc (a function) accepts a int and returns a int. Great built in functionality for Lists.  List.map for example. BTW, I don’t think I’m spilling the beans by giving away the code for Problem 1.  It by far is the easiest question, IMHO, solved by 92,000+ people. Next I’ll look into writing a class library with F#.

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• C++11 Tidbits: Decltype (Part 2, trailing return type)

  - by Paolo Carlini

  Following on from last tidbit showing how the decltype operator essentially queries the type of an expression, the second part of this overview discusses how decltype can be syntactically combined with auto (itself the subject of the March 2010 tidbit). This combination can be used to specify trailing return types, also known informally as "late specified return types". Leaving aside the technical jargon, a simple example from section 8.3.5 of the C++11 standard usefully introduces this month's topic. Let's consider a template function like: template <class T, class U> ??? foo(T t, U u) { return t + u; } The question is: what should replace the question marks? The problem is that we are dealing with a template, thus we don't know at the outset the types of T and U. Even if they were restricted to be arithmetic builtin types, non-trivial rules in C++ relate the type of the sum to the types of T and U. In the past - in the GNU C++ runtime library too - programmers used to address these situations by way of rather ugly tricks involving __typeof__ which now, with decltype, could be rewritten as: template <class T, class U> decltype((*(T*)0) + (*(U*)0)) foo(T t, U u) { return t + u; } Of course the latter is guaranteed to work only for builtin arithmetic types, eg, '0' must make sense. In short: it's a hack. On the other hand, in C++11 you can use auto: template <class T, class U> auto foo(T t, U u) -> decltype(t + u) { return t + u; } This is much better. It's generic and a construct fully supported by the language. Finally, let's see a real-life example directly taken from the C++11 runtime library as implemented in GCC: template<typename _IteratorL, typename _IteratorR> inline auto operator-(const reverse_iterator<_IteratorL>& __x, const reverse_iterator<_IteratorR>& __y) -> decltype(__y.base() - __x.base()) { return __y.base() - __x.base(); } By now it should appear be completely straightforward. The availability of trailing return types in C++11 allowed fixing a real bug in the C++98 implementation of this operator (and many similar ones). In GCC, C++98 mode, this operator is: template<typename _IteratorL, typename _IteratorR> inline typename reverse_iterator<_IteratorL>::difference_type operator-(const reverse_iterator<_IteratorL>& __x, const reverse_iterator<_IteratorR>& __y) { return __y.base() - __x.base(); } This was guaranteed to work well with heterogeneous reverse_iterator types only if difference_type was the same for both types.

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