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  • What is the purpose of Java's unary plus operator?

    - by Syntactic
    Java's unary plus operator appears to have come over from C, via C++. As near as I can tell, it has the following effects: promotes its operand to int, if it's not already an int or wider unboxes its operand, if it's a wrapper object complicates slightly the parsing of evil expressions containing large numbers of consecutive plus signs It seems to me that there are better (or, at least, clearer) ways to do all of these things. In this SO question, concerning the counterpart operator in C#, someone said that "It's there to be overloaded if you feel the need." But in Java, one cannot overload any operator. So does this operator exist in Java just because it existed in C++?

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  • A maximum character limit on the preg functions?

    - by animuson
    On my site I use output buffering to grab all the output and then run it through a process function before sending it out to the browser (I don't replace anything, just break it into more manageable pieces). In this particular case, there is a massive amount of output because it is listing out a label for every country in the database (around 240 countries). The problem is that in full, my preg_match functions seems to get skipped over, it does absolutely nothing and returns no matches. However, if I remove parts of the labels (no particular part, just random pieces to reduce characters) then the preg_match functions works again. It doesn't seem to matter what I remove from the label, it just seems to be that as long as I remove so many characters. Is there some sort of cap on what the preg functions can handle or will it time out if there is too much data to be scanned over?

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  • Subversion has --record-only for merges, how do I do the same in Git ?

    - by Paul Hammant
    I have a repo where 'master' is going in a certain direction, and a second branch 'foo' is going to be divergent for a couple of commits, then track all subsequent changes to 'master' after that. This is all by choice of course. In Subversion you could do a --record-only merge to mark things as "merge has happened" even though no actual changes were committed. i.e. this change the merge-tracking numbers in properties attached to directories in the target branch. I have had a play with.. git merge --no-commit master .. as something I may be able to tinker with before I do the commit, but it is making a hell of a mess of the target branch for part of the change in question (rename followed by delete). There must be an easier way.. ? Paul

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  • GA written in Java

    - by EnderMB
    I am attempting to write a Genetic Algorithm based on techniques I had picked up from the book "AI Techniques for Game Programmers" that uses a binary encoding and fitness proportionate selection (also known as roulette wheel selection) on the genes of the population that are randomly generated within the program in a two-dimensional array. I recently came across a piece of pseudocode and have tried to implement it, but have come across some problems with the specifics of what I need to be doing. I've checked a number of books and some open-source code and am still struggling to progress. I understand that I have to get the sum of the total fitness of the population, pick a random number between the sum and zero, then if the number is greater than the parents to overwrite it, but I am struggling with the implementation of these ideas. Any help in the implementation of these ideas would be very much appreciated as my Java is rusty.

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  • How to do a range query

    - by Walter H
    I have a bunch of numbers timestamps that I want to check against a range to see if they match a particular range of dates. Basically like a BETWEEN .. AND .. match in SQL. The obvious data structure would be a B-tree, but while there are a number of B-tree implementations on CPAN, they only seem to implement exact matching. Berkeley DB has the same problem; there are B-tree indices, but no range matching. What would be the simplest way to do this? I don't want to use an SQL database unless I have to. Clarification: I have a lot of these, so I'm looking for an efficient method, not just grep over an array.

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  • Connection to DB2 in Python

    - by Mestika
    Hi, I'm trying to create a database connection in a python script to my DB2 database. When the connection is done I've to run some different SQL statements. I googled the problem and has read the ibm_db API (http://code.google.com/p/ibm-db/wiki/APIs) but just can't seem to get it right. Here is what I got so far: import sys import getopt import timeit import multiprocessing import random import os import re import ibm_db import time from string import maketrans query_str = None conn = ibm_db.pconnect("dsn=write","usrname","secret") query_stmt = ibm_db.prepare(conn, query_str) ibm_db.execute(query_stmt, "SELECT COUNT(*) FROM accounts") result = ibm_db.fetch_assoc() print result status = ibm_db.close(conn) but I get an error. I really tried everything (or, not everything but pretty damn close) and I can't get it to work. I just need to make a automatic test python script that can test different queries with different indexes and so on and for that I need to create and remove indexes a long the way. Hope someone has a solutions or maybe knows about some example codes out there I can download and study. Thanks Mestika

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  • wrapping aspx user controls commands in a transaction

    - by Hans Gruber
    I'm working on heavily dynamic and configurable CMS system. Therefore, many pages are composed of a dynamically loaded set of user controls. To enable loose coupling between containers (pages) and children (user controls), all user controls are responsible for their own persistence. Each User Control is wired up to its data/service layer dependencies via IoC. They also implement an IPersistable interface, which allows the container .aspx page to issue a Save command to its children without knowledge of the number or exact nature of these user controls. Note: what follows is only pseudo-code: public class MyUserControl : IPersistable, IValidatable { public void Save() { throw new NotImplementedException(); } public bool IsValid() { throw new NotImplementedException(); } } public partial class MyPage { public void btnSave_Click(object sender, EventArgs e) { foreach (IValidatable control in Controls) { if (!control.IsValid) { throw new Exception("error"); } } foreach (IPersistable control in Controls) { if (!control.Save) { throw new Exception("error"); } } } } I'm thinking of using declarative transactions from the System.EnterpriseService namespace to wrap the btnSave_Click in a transaction in case of an exception, but I'm not sure how this might be achieved or any pitfalls to such an approach.

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  • The fastest way to iterate through a collection of objects

    - by Trev
    Hello all, First to give you some background: I have some research code which performs a Monte Carlo simulation, essential what happens is I iterate through a collection of objects, compute a number of vectors from their surface then for each vector I iterate through the collection of objects again to see if the vector hits another object (similar to ray tracing). The pseudo code would look something like this for each object { for a number of vectors { do some computations for each object { check if vector intersects } } } As the number of objects can be quite large and the amount of rays is even larger I thought it would be wise to optimise how I iterate through the collection of objects. I created some test code which tests arrays, lists and vectors and for my first test cases found that vectors iterators were around twice as fast as arrays however when I implemented a vector in my code in was somewhat slower than the array I was using before. So I went back to the test code and increased the complexity of the object function each loop was calling (a dummy function equivalent to 'check if vector intersects') and I found that when the complexity of the function increases the execution time gap between arrays and vectors reduces until eventually the array was quicker. Does anyone know why this occurs? It seems strange that execution time inside the loop should effect the outer loop run time.

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  • Removing whitespace between HTML elements when using line breaks

    - by Skilldrick
    I have a page with a row of about 10 imgs. For readability of the HTML, I want to put a linebreak in between each img tag, but doing so renders whitespace between the images, which I do not want. Is there anything I can do other than break in the middle of the tags rather than between them? Edit: Here is a screenshot of what I have so far. I would like the book spine images to display in random combinations, using PHP. This is why I need separate img tags.

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  • How to use a proprety/value table in MySQL

    - by David
    I inherited a mysql database that has a table with columns like this: object_id, property, value It holds data like this: 1,first_name,Jane 1,last_name,Doe 1,age,10 1,color,red 2,first_name,Mike 2,last_name,Smith 2,age,20 2,color,blue 3,first_name,John 3,last_name,Doe 3,age,20 3,color,red ... Basically what I want to do is treat this table as a regular table. How would I get the id numbers (or all properties) of a person who is age 20 sorted by last and than first name? So far I have: SELECT object_id FROM table WHERE property = 'age' AND value = '20' union SELECT object_id FROM table WHERE property = 'color' AND value = 'red' But I'm not sure how to go about ordering the data. Thanks

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  • With the advent of HTML 5, is there a point in using COMET anymore?

    - by h2g2java
    I am very tempted to use long wait http or periodic polling by the client to set up pseudo-sockets on the browser side, for an application that would be used publicly. But then on the 2nd thought, I am thinking HTML 5 is here. But on the 3rd thought, what is the percentage of browsers out there that remain non-HTML5 within 12 months, 24 months, 36 months? If there are at least 20% of browsers still incapable of HTML5, then I cannot depend on HTML5 because 20% of users not being able to access an application is a significant amount. What do you think, how would your advice be (to me and to developers in general)? Q1. Is there any point in rigging in COMET into an application anymore? I am thinking of gwt comet - http://code.google.com/p/gwt-comet/. Q2. Should we release a new public application within the next 2 months that is dependent on HTML5 sockets and tell non-HTML5 browser users "sorry, your browser version cannot access this application"? Or should we architect the apps to use communication like GWT RPC? Q3. I am also very distrustful of long wait http request. I have never used it before but I have a horrible feeling about it. I have been using 10 to 20 second client-side polling. Is long wait http request risky (risk of hanging a browser session)? Does long wait request present any additional security risk?

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  • Use JavaScript to Replace Classname Value

    - by user1515425
    I want to replace every occurrence of the numbers with the string: ???. Here is an example string: <em>Chelsea</em> 1-4 Atletico Madrid How can I do this in JavaScript? <a href="https://www.google.com/url?sa=t&amp;source=web&amp;cd=9&amp;cad=rja&amp;ved=0CFEQtwIwCA&amp;url=http%3A%2F%2Fwww.whoateallthepies.tv%2Fchelsea%2F137070%2Fsuper-cup-chelsea-1-4-atletico-madrid-falcao-on-fire-as-blues-flop-in-monaco-photos-highlights.html&amp;rct=j&amp;q=chelsea&amp;ei=1odBUImpBIWA0AWM1oC4BA&amp;usg=AFQjCNEwdCCckt15XTkHSAf2fsUnGk9IJg&amp;sig2=IOrD6hfMrviW9ods0DG2dw" class="l" onmousedown="return rwt(this,'','0','','9','AFQjCNEwdCCckt15XTkHSAf2fsUnGk9IJg','IOrD6hfMrviW9ods0DG2dw','0CFEQtwIwCA',null,event)" title="Super Cup: Chelsea 1-4 Atletico Madrid – Falcao On Fire As Blues Flop In Monaco (Photos ...">Super Cup: <em>Chelsea</em> 1-4 Atletico Madrid – Falcao On <b>...</b></a> Thanks in advance.

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  • Are there any widely-agreed upon guidelines for rating your language knowledge on a scale?

    - by DVK
    The question was imagined after a co-worker was complaining for an hour about some guy who could not answer basic Java questions on an interview after self-identifying himself as "8 out of 10" on Java. While that was an obvious fib, I personally always had major trouble defining my specific language skills on a sliding scale unless I'm given specific guidelines (remember 40 standard libraries by heart? Able to solve 10 random Project Euler problems in <30 mins each? Can write implementation of A, B and C data-structures from scratch in 30 mins? Know 30% of standard? Can answer 50% of questions on StackOverflow pertaining to the language?) So, I was wondering - is there some sort of commonly accepted methodology for translating such tangible benchmarks into "rate yourself on a language between 1-10"? "Kernighan gets an A, God gets a B, everyone else gets C and less" type jokes are not helpful :)

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  • How to create a view of table that contains a timestamp column?

    - by Matt Faus
    This question is an extension of a previous one I have asked. I have a table (2014_05_31_transformed.Video) with a schema that looks like this. I have put up the JSON returned by the BigQuery API describing it's schema in this gist. I am trying to create a view against this table with an API call that looks like this: { 'view': { 'query': u 'SELECT deleted_mod_time FROM [2014_05_31_transformed.Video]' }, 'tableReference': { 'datasetId': 'latest_transformed', 'tableId': u 'Video', 'projectId': 'redacted' } } But, the BigQuery API is returning this error: HttpError: https://www.googleapis.com/bigquery/v2/projects/124072386181/datasets/latest_transformed/tables?alt=json returned "Invalid field name "deleted_mod_time.usec". Fields must contain only letters, numbers, and underscores, start with a letter or underscore, and be at most 128 characters long." The schema that the BigQuery API does not make any distinction between a TIMESTAMP data type and a regular nullable INTEGER data type, so I can't think of a way to programmatically correct this problem. Is there anything I can do, or is this a bug with BigQuery's view implementation?

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  • Why won't this SQL CAST work?

    - by Kev
    I have a nvarchar(50) column in a SQL Server 2000 table defined as follows: TaskID nvarchar(50) NULL I need to fill this column with some random SQL Unique Identifiers (I am unable to change the column type to uniqueidentifier). I tried this: UPDATE TaskData SET TaskID = CAST(NEWID() AS nvarchar) but I got the following error: Msg 8115, Level 16, State 2, Line 1 Arithmetic overflow error converting expression to data type nvarchar. I also tried: UPDATE TaskData SET TaskID = CAST(NEWID() AS nvarchar(50)) but then got this error: Msg 8152, Level 16, State 6, Line 1 String or binary data would be truncated. I don't understand why this doesn't work but this does: DECLARE @TaskID nvarchar(50) SET @TaskID = CAST(NEW() AS nvarchar(50)) I also tried CONVERT(nvarchar, NEWID()) and CONVERT(nvarchar(50), NEWID()) but got the same errors.

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  • What does 'salt' refer to in string-to-key (s2k) specifier?

    - by WilliamKF
    What does 'salt' refer to in string-to-key (s2k) specifier? It appears to be a random number generator to shake things up, but I would like to know what 'salt' stands for? For example it is written: 3.6.1.2. Salted S2K This includes a "salt" value in the S2K specifier -- some arbitrary data -- that gets hashed along with the passphrase string, to help prevent dictionary attacks. Octet 0: 0x01 Octet 1: hash algorithm Octets 2-9: 8-octet salt value Salted S2K is exactly like Simple S2K, except that the input to the hash function(s) consists of the 8 octets of salt from the S2K specifier, followed by the passphrase. But salt is not defined, although its meaning seems clear.

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  • asp.net mvc validation must be a number custom error

    - by Para
    Hi, I am new to asp.net and I have a problem. When the users insert in a editor for a decimal field something other than numbers, they get an error "Field name" is not a number. But I don't want them to receive this message I want them to receive another message. I have no problem with this with required and range validators. Is there any way for me to do this? I am not refering necessarily to changing the culture just displaying another message. Thanks.

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  • How to set Chrome's user script version number.

    - by Atli
    Hey. I've been wondering how I might set the version number displayed for user-scripts in Chrome's extension tab So far the obvious methods have failed: // ==UserScript== // @version 1.1.5 // @uso:version 1.1.5 // ==/UserScript== I know Greasemonkey for Firefox doesn't use a version value, but since Chrome actually displays a version number, I thought it might. Perhaps this is a feature that has not been implemented? Or maybe it was never intended to be there, but it is there because extensions have version numbers, and user-scripts are currently installed as extensions? (I'm using the Linux beta, version: 4.0.249.43, by the way) Thanks. Edit: Seems this is listed as an unconfirmed bug in the Chromium bug database (Issue 30760)

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  • Using the value of a variable as another variables name in Ruby

    - by hrickards
    Hi, I'm just starting out in learning Ruby and I've written a program that generates some numbers and assigns them to variables @one, @two, @three etc. The user can then specify a variable to change by inputting it's name (e.g one). I then need to do something like '@[valueofinout] = asd'. How would I do this, and is there a better way as the way I'm thinking of seems to be discouraged? I've found x = "myvar" myvar = "hi" eval(x) -> "hi" but I don't completely understand why the second line is needed. In my case would I use something like @one = "21" input = "one" input = "@" + input changeto = "22" eval(input) -> changeto Thanks

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  • call multiple c++ functions in python using threads

    - by wiso
    Suppose I have a C(++) function taking an integer, and it is bound to (C)python with python api, so I can call it from python: import c_module c_module.f(10) now, I want to parallelize it. The problem is: how does the GIL work in this case? Suppose I have a queue of numbers to be processed, and some workers (threading.Thread) working in parallel, each of them calling c_module.f(number) where number is taken from a queue. The difference with the usual case, when GIL lock the interpreter, is that now you don't need the interpreter to evaluate c_module.f because it is compiled. So the question is: in this case the processing is really parallel?

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  • Only the last run in a for loop in Javascript works

    - by Mengfei Murphy
    Here is a for loop written by Javascript. It is trying to apply queries for websql. for (var i = 0; i < 10; i++){ db.transaction(function (tx){ tx.executeSql('INSERT INTO ProjSetsT (ProjID) VALUES (?);', [i]); }); } The attempt is obvious, I tried to add values "0, 1, 2, ... 9" into column ProjID in table ProjSetsT. It does not work. I only got the last element, i.e. "9" inserted, but not the first eight numbers. Is there any syntax mistakes?

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  • Oracle - Is there any effects of not having a primary key on a table ?

    - by Sathya
    We use sequence numbers for primary keys on the tables. There are some tables where we dont really use the primary key for any querying purpose. But, we have Indexes on other columns. These are non-unique indexes. The queries use these non-primary key columns in the WHERE conditions. So, I dont really see any benefit of having a primary key on such tables. My experience with SQL 2000 was that, it used to replicate tables which had some primary key. Otherwise it would not. I am using Oracle 10gR2. I would like to know if there are any such side-effects of having tables that dont have primary key.

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  • How do I get Git's latest stable release version number?

    - by MattDiPasquale
    I'm writing a git-install.sh script: http://gist.github.com/419201 To get Git's latest stable release version number, I do: LSR_NUM=$(curl -silent http://git-scm.com/ | sed -n '/id="ver"/ s/.*v\([0-9].*\)<.*/\1/p') 2 Questions: Refactor my code: Is there a better way programmatically to do this? This works now, but it's brittle: if the web page at http://git-scm.com/ changes, the line above may stop working. PHP has a reliable URL for getting the latest release version: http://stackoverflow.com/questions/288206/is-there-a-site-which-simply-outputs-the-latest-stable-version-numbers-of-php-and Is there something like this for Git? This comes close: http://www.kernel.org/pub/software/scm/git/

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  • Open source configuration framework for ASP.NET - does one exist?

    - by Jon
    We currently have an old product written in classic asp and are about to re-write parts in ASP.NET. One big problem is that much of the cutomer-specifics within the system are hard coded. We want to split this out for specific customers by storing data in the database. Is there a quick an easy open source framework which allows me to set up some quick tables and simple UIs to allow me to change configuration items? We have 6-7 modules, and it would be nice to have the ability to have system admins gain access to a configuration area where they can set-up settings in a tabbed UI format, settings could also be set-up to allow dropdown, fields, numbers etc. The items could then be accessed via classes in C#/vb for use within the operational parts of the system. If not, I'm suprised and it might even be a good basis for a new open source project.

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  • Is it bad use "display: table;" to organise a layout into 2 columns?

    - by Colen
    Hello, I am trying to make a 2 column layout, apparently the bane of CSS. I know you shouldn't use tables for layout, but I've settled on this CSS. Note the use of display: table etc. div.container { width: 600px; height: 300px; margin: auto; display: table; table-layout: fixed; } ul { white-space: nowrap; overflow: hidden; display: table-cell; width: 40%; } div.inner { display: table-cell; width: auto; } With this layout: <div class="container"> <ul> <li>First</li> <li>Second</li> <li>Third</li> </ul> <div class="inner"> <p>Hello world</p> </div> </div> This seems to work admirably. However, I can't help wondering - am I obeying the letter of the "don't use tables" rule, but not the spirit? I think it's ok, since there's no positioning markup in the HTML code, but I'm just not sure about the "right" way to do it. I can't use css float, because I want the columns to expand and contract with the available space. Please, stack overflow, help me resolve my existential sense of dread at these pseudo-tables.

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