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• Should I use C++0x Features Now?

  - by svu2g

  With the official release of VS 2010, is it safe for me to start using the partially-implemented C++0x feature set in my new code? The features that are of interest to me right now are both implemented by VC++ 2010 and recent versions of GCC. These are the only two that I have to support. In terms of the "safety" mentioned in the first sentence: can I start using these features (e.g., lambda functions) and still be guaranteed that my code will compile in 10 years on a compiler that properly conforms to C++0x when it is officially released? I guess I'm asking if there is any chance that VC++ 2010 or GCC will end up like VC++ 6; it was released before the language was officially standardized and consequently allowed grossly ill-formed code to compile. After all, Microsoft does say that "10 is the new 6". ;)

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• does a switch idiom make sense in this case?

  - by the ungoverned

  I'm writing a parser/handler for a network protocol; the protocol is predefined and I am writing an adapter, in python. In the process of decoding the incoming messages, I've been considering using the idiom I've seen suggested elsewhere for "switch" in python: use a hash table whose keys are the field you want to match on (a string in this case) and whose values are callable expressions: self.switchTab = { 'N': self.handleN, 'M': self.handleM, ... } Where self.handleN, etc., are methods on the current class. The actual switch looks like this: self.switchTab[selector]() According to some profiling I've done with cProfile (and Python 2.5.2) this is actually a little bit faster than a chain of if..elif... statements. My question is, do folks think this is a reasonable choice? I can't imagine that re-framing this in terms of objects and polymorphism would be as fast, and I think the code looks reasonably clear to a reader.

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• How do I programmatically set property of control in aspx file ?

  - by Thomas Wanner

  This may be a very dumb question but I can't seem to get it working. I use at many places the following syntax for dynamically binding a property of a control in aspx file to the resource entry, e.g. <SomeFunnyControl Text="<%$ Resources : ResClass, ResEntry %>" /> I want to do a similar thing with a class containing some constants, something like <SomeFunnyControl Text="<%= MyConstantsClass.MyStringConstant %>" /> But this doesn't seem to work, it simply sets the text to the exact expression without evaluating it. I am using ASP.NET 3.5 btw. I have tried the databinding approach but I get an HttpParseException saying Databinding expressions are only supported on objects that have a DataBinding event.

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• Determine if a string contains only alphanumeric characters (or a space)

  - by dreamlax

  I'm learning C++ and I am writing a function that determines whether a string contains only alphanumeric characters and spaces. I suppose I am effectively testing whether it matches the regular expression ^[[:alnum:] ]+$ but without using regular expressions. I have seen a lot of algorithms revolve around iterators, so I tried to find a solution that made use of iterators, and this is what I have: #include <algorithm> static inline bool is_not_alnum_space(char c) { return !(isalpha(c) || isdigit(c) || (c == ' ')); } bool string_is_valid(const std::string &str) { return find_if(str.begin(), str.end(), is_not_alnum_space) == str.end(); } Is there a better solution, or a “more C++” way to do this?

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• Effecient data structure design

  - by Sway

  Hi there, I need to match a series of user inputed words against a large dictionary of words (to ensure the entered value exists). So if the user entered: "orange" it should match an entry "orange' in the dictionary. Now the catch is that the user can also enter a wildcard or series of wildcard characters like say "or__ge" which would also match "orange" The key requirements are: * this should be as fast as possible. * use the smallest amount of memory to achieve it. If the size of the word list was small I could use a string containing all the words and use regular expressions. however given that the word list could contain potentially hundreds of thousands of enteries I'm assuming this wouldn't work. So is some sort of 'tree' be the way to go for this...? Any thoughts or suggestions on this would be totally appreciated! Thanks in advance, Matt

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• Using Rails and Rspec, how do you test that the database is not touched by a method

  - by Will Tomlins

  So I'm writing a test for a method which for performance reasons should achieve what it needs to achieve without using SQL queries. I'm thinking all I need to know is what to stub: describe SomeModel do describe 'a_getter_method' do it 'should not touch the database' do thing = SomeModel.create something_inside_rails.should_not_receive(:a_method_querying_the_database) thing.a_getter_method end end end EDIT: to provide a more specific example: class Publication << ActiveRecord::Base end class Book << Publication end class Magazine << Publication end class Student << ActiveRecord::Base has_many :publications def publications_of_type(type) #this is the method I am trying to test. #The test should show that when I do the following, the database is queried. self.publications.find_all_by_type(type) end end describe Student do describe "publications_of_type" do it 'should not touch the database' do Student.create() student = Student.first(:include => :publications) #the publications relationship is already loaded, so no need to touch the DB lambda { student.publications_of_type(:magazine) }.should_not touch_the_database end end end So the test should fail in this example, because the rails 'find_all_by' method relies on SQL.

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• C++ boost or STL `y += f(x)` type algorithm

  - by aaa

  hello. I know I can do this y[i] += f(x[i]) using transform with two input iterators. however it seems somewhat counterintuitive and more complicated than for loop. Is there a more natural way to do so using existing algorithm in boost or Stl. I could not find clean equivalent. here is transform (y = y + a*x): using boost::lambda; transform(y.begin(), y.end(), x.begin(), y.begin(), (_1 + scale*_2); // I thought something may exist: transform2(x.begin(), x.end(), y.begin(), (_2 + scale*_1); // it does not, so no biggie. I will write wrapper Thanks

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• Detecting regular expression in content during parse

  - by sonofdelphi

  I am writing a parser for C. I was just running it with some other language files (for fun, to see the extent C-likeness). It breaks down if the code being parsed contains regular expressions... Case 1: For example, while parsing the JavaScript code snippet, var phone="(304)434-5454" phone=phone.replace(/[\(\)-]/g, "") //Returns "3044345454" (removes "(", ")", and "-") The '(', '[' etc get matched as starters of new scopes, which may never be closed. Case 2: And, for the Perl code snippet, # Replace backslashes with two forward slashes # Any character can be used to delimit the regex $FILE_PATH =~ s@\\@//@g; The // gets matched as a comment... How can I detect a regular expression within the content text of a "C-like" program-file?

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• Sql Server Where Case Then Is Null Else Is Not Null

  - by Fabio Montezuma

  I have a procedure which receive a bit variable called @FL_FINALIZADA. If it is null or false I want to restrict my select to show only the rows that contain null DT_FINALIZACAO values. Otherwise I want to show the rows containing not null DT_FINALIZACAO values. Something like this: SELECT * FROM ... WHERE ... AND (OPE.DT_FINALIZACAO = CASE WHEN (@FL_FINALIZADA <> 1) THEN NULL END OR OPE.DT_FINALIZACAO IS NOT NULL) In this case I receive the message: None of the result expressions in a CASE specification can be NULL. How can I achieve this? Thanks in advance.

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• Best approch to dynamically filter .net objects

  - by maxba

  The project i´m working currently on has a way to define a filter to filter objects from a database. This filter is a pretty straitforward class containing filtercriteria that will be combined to a sql where-clause. The goal now is to use this filter class to filter .net objects as well. So the filter for example defines, that the title property of the object that it is applied to must contain some userdefined string etc. What are ways to approch this problem? What should the filter return instead of the sql where-clause and how can it be applied to the object? I´m thinking about this for hours and don´t yet have even a slight idea how to solve this. Been thinking about reflection, dynamic code execution, building expressions but still haven´t found an acutal starting point.

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• How to always return a set number of records when using find_related_tags with acts-as-taggable-on

  - by hadees

  I'm using the acts-as-taggable-on gem and I need to use find_related_tags on my survey model to get back 3 surveys every time. In the event there aren't always 3 related I need to pick how ever many are related plus some random ones to get to 3. Additionally I have a method I wrote called completed_survey_ids which return an array of survey_ids that shouldn't be used because the user has already completed them. Also there is a rare case that there won't be enough surveys because the user has completed them all so in that event it is okay to return less surveys then requested. I did write a named_scope to handle getting rid of the completed_survey_ids that I think works named_scope :not, lambda { |survey_ids| {:conditions => "id NOT IN (#{survey_ids.join(',')})" } }

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• C# Dynamic Query Without A Database Model

  - by hitopp

  I have been searching the web for a solution to dynamic queries. I have found many different solutions (e.g. Linq to Sql, Dynamic Linq Expressions, Dynamic Query), but all of these solutions involve some sort of previous knowledge of the database (like a model in code). Maybe what I am asking is way off the deep end, but is there any possible way to dynamically query a database without a model? For example, a database has a Customers table with the following columns: CustomerID Name FavoriteColor I want to create a query as SELECT Name FROM Customers WHERE @0 = @1, where the two placeholders are populated dynamically. The resulting data does not tie to a model class and I would prefer to use some sort of framework to build the queries, not simple string concatenation. The System.Linq.Dynamic namespace came really close to fulfilling this request, but it uses a database model. I realize this is crazy, but I was just curious.

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• Are there .NET Framework methods to parse an email (MIME)?

  - by Neil C. Obremski

  Is there a class or set of functions built into the .NET Framework (3.5+) to parse raw emails (MIME documents)? I am not looking for anything fancy or a separate library, it needs to be built-in. I'm going to be using this in some unit tests and need only grab the main headers of interest (To, From, Subject) along with the body (which in this case will always be text and therefore no MIME trees or boundaries). I've written several MIME parsers in the past and if there isn't anything readily available, I'll just put together something from regular expressions. It would be great to be able to do something like: MailMessage msg = MailMessage.Parse(text); Thoughts?

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• Rewriting usort function because of fatal error (PHP bug)

  - by Lionel

  The two following usort functions throw fatal error Base lambda function for closure not found in our productive environment (PHP 5.4). This seems to be a known PHP bug that should be fixed by now (https://bugs.php.net/bug.php?id=52144), but it still occurs for us. Anyway, we unfortunately don't have time to figure out what's wrong with our PHP configurations etc. We would like to rewrite these two functions without the use of anonymous functions, so that the error doesn't occur anymore. Ordering of a multidimensional array ($array) by value of key "position": usort($array, function($a, $b) { return $a['position'] - $b['position']; }); Ordering of a multidimensional array ($array) according to the order of a second array ($position_order): usort($array, function($a, $b) use($position_order) { return (isset($position_order[$a['ftid']]) ? ($position_order[$a['ftid']] - $position_order[$b['ftid']]) : 1); }); Especially the latter causes some headache, as we don't know how to pass the "outside" array $position_order.

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• Problem when reading backslash in Prolog

  - by Jerry

  I'm writing a lexer in Prolog which will be used as a part of functional language interpreter. Language spec allows expressions like for example let \x = x + 2; to occur. What I want lexer to do for such input is to "return": [tokLet, tokLambda, tokVar(x), tokEq, tokVar(x), tokPlus, tokNumber(2), tokSColon] and the problem is, that Prolog seems to ignore the \ character and "returns" the line written above except for tokLambda. One approach to solve this would be to somehow add second backslash before/after every occurrence of one in the program code (because everything works fine if I change the original input to let \\x = x + 2;) but I don't really like it. Any ideas?

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• How do I write a scheme macro that defines a variable and also gets the name of that variable as a s

  - by Jason Baker

  This is mostly a follow-up to this question. I decided to just keep YAGNI in mind and created a global variable (libpython). I set it to #f initially, then set! it when init is called. I added a function that should handle checking if that value has been initialized: (define (get-cpyfunc name type) (lambda args (if libpython (apply (get-ffi-obj name libpython type) args) (error "Call init before using any Python C functions")))) So now here's what I want to do. I want to define a macro that will take the following: (define-cpyfunc Py_Initialize (_fun -> _void)) And convert it into this: (define Py_Initialize (get-cpyfunc "Py_Initialize" (_fun -> _void))) I've been reading through the macro documentation to try figuring this out, but I can't seem to figure out a way to make it work. Can anyone help me with this (or at least give me a general idea of what the macro would look like)? Or is there a way to do this without macros?

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• Regular expression match, extracting only wanted segments of string

  - by Ben Carey

  I am trying to extract three segments from a string. As I am not particularly good with regular expressions, I think what I have done could probably be done better... I would like to extract the bold parts of the following string: SOMETEXT: ANYTHING_HERE (Old=ANYTHING_HERE, New=ANYTHING_HERE) Some examples could be: ABC: Some_Field (Old=,New=123) ABC: Some_Field (Old=ABCde,New=1234) ABC: Some_Field (Old=Hello World,New=Bye Bye World) So the above would return the following matches: $matches[0] = 'Some_Field'; $matches[1] = ''; $matches[2] = '123'; So far I have the following code: preg_match_all('/^([a-z]*\:(\s?)+)(.+)(\s?)+\(old=(.+)\,(\s?)+new=(.+)\)/i',$string,$matches); The issue with the above is that it returns a match for each separate segment of the string. I do not know how to ensure the string is the correct format using a regular expression without catching and storing the match if that makes sense? So, my question, if not already clear, how I can retrieve just the segments that I want from the above string?

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• Regex expression with leading zero

  - by user1874087

  I'm rather new to regex expressions and need help with a simple expression. I'm using Pentaho for ETL (Replace in String transformation) and I have column values that I need to add leading zeros to and parse out text as part of the database import. So far I have been unable to add the leading zero. The column is called Region and the values are "region 8", "region 10", "region 11". My regex expression is ['Region'] which will eliminate the region text but produces results = "8", "10", "11". I need values to produce "08", "10", "11". So all the single digit numbers must have leading zeros.

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• regular expression to check file content type is .doc or not?

  - by Pandiya Chendur

  When i use a file upload i use to check file contenttype with regular expressions... For ex private bool IsImage(HttpPostedFile file) { if (file != null && Regex.IsMatch(file.ContentType, "image/\\S+") && file.ContentLength > 0) { return true; } return false; } This returns my file is an image or not... How to check it is a word(.doc/.docx) document or not using c#...

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• Extracting property names from a c# source file

  - by Pete

  I want to parse a c# file. The only thing I want is to determine if it contains a property with a specific name; just a simple true/false response. Or rather, since I'd checking for more than one property in each run, extracting a list of property names could be helpful I thought that I could create an elegant solution using the CodeDomProvider functionality (f# example): use reader = new StreamReader(existingFile) let codeProvider = new CSharpCodeProvider() let codeUnit = codeProvider.Parse(reader) Unfortunately, the Parse function is not implemented for the CSharpCodeProvider. Is there a way to get a CodeCompileUnit from a source file? Or is there another elegant way? (I had hoped to avoid regular expressions on this)?

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• How to sort a list by the 2nd tuple element in python and C#

  - by user350468

  I had a list of tuples where every tuple consists of two integers and I wanted to sort by the 2nd integer. After looking in the python help I got this: sorted(myList, key=lambda x: x[1]) which is great. My question is, is there an equally succinct way of doing this in C# (the language I have to work in)? I know the obvious answer involving creating classes and specifying an anonymous delegate for the whole compare step but perhaps there is a linq oriented way as well. Thanks in advance for any suggestions.

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• Apply function to one element of a list in Python

  - by user189637

  I'm looking for a concise and functional style way to apply a function to one element of a tuple and return the new tuple, in Python. For example, for the following input: inp = ("hello", "my", "friend") I would like to be able to get the following output: out = ("hello", "MY", "friend") I came up with two solutions which I'm not satisfied with. One uses a higher-order function. def apply_at(arr, func, i): return arr[0:i] + [func(arr[i])] + arr[i+1:] apply_at(inp, lambda x: x.upper(), 1) One uses list comprehensions (this one assumes the length of the tuple is known). [(a,b.upper(),c) for a,b,c in [inp]][0] Is there a better way? Thanks!

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• Java Counting # of occurrences of a word in a string

  - by Doug

  I have a large text file I am reading from and I need to find out how many times some words come up. For example, the word "the". I'm doing this line by line each line is a string. I need to make sure that I only count legit "the"'s the the in other would not count. This means I know I need to use regular expressions in some way. What I was trying so far is this: numSpace += line.split("[^a-z]the[^a-z]").length; I realize the regular expression may not be correct at the moment but I tried without that and just tried to find occurrences of the word the and I get wrong numbers to. I was under the impression this would split the string up into an array and how many times that array was split up was how many times the word is in the string. Any ideas I would be grateful.

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• Passing dependent objects to a parent constructor in Scala

  - by Nick Johnson

  Suppose I have the following class heirarchy: class A() class B(a:A) class C(b:B) class BaseClass(b:B, c:C) Now I want to implement a subclass of BaseClass, which is given an instance of A, and constructs instances of B and C, which it passes to its superclass constructor. If I could use arbitrary expressions, I'd do something like this: b = new B(a) c = new C(b) super(b, c) Because the second argument to the parent constructor depends on the value of the first argument, though, I can't see any way to do this, without using a factory function, or a gratuitous hack, such as : class IntermediateSubclass(b:B) extends BaseClass(b, new C(b)) class RealSubclass(a:A) extends IntermediateSubclass(new B(a)) Is there clean way to do this?

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• Interacting With Class Objects in Ruby

  - by michaelmichael

  How can I interact with objects I've created based on their given attributes in Ruby? To give some context, I'm parsing a text file that might have several hundred entries like the following: ASIN: B00137RNIQ -------------------------Status Info------------------------- Upload created: 2010-04-09 09:33:45 Upload state: Imported Upload state id: 3 I can parse the above with regular expressions and use the data to create new objects in a "Product" class: class Product attr_reader :asin, :creation_date, :upload_state, :upload_state_id def initialize(asin, creation_date, upload_state, upload_state_id) @asin = asin @creation_date = creation_date @upload_state = upload_state @upload_state_id = upload_state_id end end After parsing, the raw text from above will be stored in an object that look like this: [#<Product:0x00000101006ef8 @asin="B00137RNIQ", @creation_date="2010-04-09 09:33:45 ", @upload_state="Imported ", @upload_state_id="3">] How can I then interact with the newly created class objects? For example, how might I pull all the creation dates for objects with an upload_state_id of 3? I get the feeling I'm going to have to write class methods, but I'm a bit stuck on where to start.

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