Search Results

Search found 686 results on 28 pages for 'christopher johnson'.

Page 20/28 | < Previous Page | 16 17 18 19 20 21 22 23 24 25 26 27  | Next Page >

  • Hashing a python method to regenerate output when method is modified

    - by Seth Johnson
    I have a python method that has a deterministic result. It takes a long time to run and generates a large output: def time_consuming_method(): # lots_of_computing_time to come up with the_result return the_result I modify time_consuming_method from time to time, but I would like to avoid having it run again while it's unchanged. [Time_consuming_method only depends on functions that are immutable for the purposes considered here; i.e. it might have functions from Python libraries but not from other pieces of my code that I'd change.] The solution that suggests itself to me is to cache the output and also cache some "hash" of the function. If the hash changes, the function will have been modified, and we have to re-generate the output. Is this possible or a ridiculous idea? If this isn't a terrible idea, is the best implementation to write f = """ def ridiculous_method(): a = # # lots_of_computing_time return a """ , use the hashlib module to compute a hash for f, and use compile or eval to run it as code?

    Read the article

  • Implementing a scalable and high-performing web app

    - by Christopher McCann
    I have asked a few questions on here before about various things relating to this but this is more of a consolidation question as I would like to check I have got the gist of everything. I am in the middle of developing a social media web app and although I have a lot of experience coding in Java and in PHP I am trying things a bit different this time. I have modularised each component of the application. So for example one component of the application allows users to private message each other and I have split this off into its own private messaging service. I have also created a user data service the purpose of which is to return data about the user for example their name, address, age etc etc from the database. Their is also another service, the friends service, which will work off the neo4j database to create a social graph. My reason for doing all this is to allow me up to update seperate modules when I need to - so while they mostly all run off MySQL right now I could move one to Cassandra later if I thought it approriate. The actual code of the web app is really just used for the final construction. The modules behind it dont really follow any strict REST or SOAP protocol. Basically each method on our API is turned into a PHP procedural script. This then may make calls to other back-end code which tends to be OO. The web app makes CURL requests to these pages and POSTs data to them or GETs data from them. These pages then return JSON where data is required. I'm still a little mixed up about how I actually identify which user is logged in at that moment. Do I just use sessions for that? Like if we called the get-messages.php script which equates to the getMessages() method for that user - returning all the private messages for that user - how would the back-end code know which user it is as posting the users ID to the script would not be secure. Anyone could do that and get all the messages. So I thought I would use sessions for it. Am I correct on this? Can anyone spot any other problems with what I am doing here? Thanks

    Read the article

  • What is recursion? -- In plain english.

    - by Christopher Altman
    I hear this word everyday, but cannot give a meaningful, concise, or plain-english answer to what it is. Recursion is defined by the bastian of knowledge as: Recursion in computer science is a method where the solution to a problem depends on solutions to smaller instances of the same problem.1 The approach can be applied to many types of problems, and is one of the central ideas of computer science.[2] Source Is recursion simply something that repeats itself to get a solution? I am looking for a "Recursion for Dummies" definition, and maybe simple examples. My goal is to be able to understand and explain recursion in my own words. I do not like simply thinking I know the meaning of something because I hear it referenced daily, but have not paused to form my own understanding.

    Read the article

  • Sync Algorithms

    - by Kristopher Johnson
    Are there any good references out there for sync algorithms? I'm interested in algorithms that synchronize the following kinds of data between multiple users: calendars documents lists and outlines I'm not just looking for synchronization of contents of directories a la rsync; I am interested in merging the data within individual files.

    Read the article

  • Git: changes not reflecting on other checkouts - huh?

    - by Chad Johnson
    Okay, so, I have my branches (git branch -a): * chat master remotes/origin/HEAD -> origin/master remotes/origin/chat I make changes (still with the 'chat' branch checkout out), commit, and push. I go to my server, on which I have a clone of the repository, and I do a fetch: git getch then I switch to the chat branch: git checkout --track -b chat origin/chat and I event do a pull, just to make sure everything is up to date: git pull and my changes from my other computer are NOT. THERE. What the heck am I doing wrong? If I had hair, I would have pulled it out. Thankfully I am bald. When I try a 'git commit' again, I get this # On branch chat # Changed but not updated: # (use "git add/rm <file>..." to update what will be committed) # (use "git checkout -- <file>..." to discard changes in working directory) # # modified: app/controllers/chat_controller.rb # modified: app/views/dashboard/index.html.erb # modified: app/views/dashboard/layout.js.erb # modified: app/views/layouts/dashboard.html.erb # deleted: app/views/project/.tmp_edit.html.erb.55742~ # deleted: app/views/project/.tmp_edit.html.erb.83482~ # modified: public/stylesheets/dashboard/layout.css # # Untracked files: # (use "git add <file>..." to include in what will be committed) # # .loadpath # .project # config/database.yml # config/environments/development.yml # config/environments/production.yml # config/environments/test.yml # log/ no changes added to commit (use "git add" and/or "git commit -a")

    Read the article

  • Do You Really Know Your Programming Languages?

    - by Kristopher Johnson
    I am often amazed at how little some of my colleagues know or care about their craft. Something that constantly frustrates me is that people don't want to learn any more than they need to about the programming languages they use every day. Many programmers seem content to learn some pidgin sub-dialect, and stick with that. If they see a keyword or construct that they aren't familiar with, they'll complain that the code is "tricky." What would you think of a civil engineer who shied away from calculus because it had "all those tricky math symbols?" I'm not suggesting that we all need to become "language lawyers." But if you make your living as a programmer, and claim to be a competent user of language X, then I think at a minimum you should know the following: Do you know the keywords of the language and what they do? What are the valid syntactic forms? How are memory, files, and other operating system resources managed? Where is the official language specification and library reference for the language? The last one is the one that really gets me. Many programmers seem to have no idea that there is a "specification" or "standard" for any particular language. I still talk to people who think that Microsoft invented C++, and that if a program doesn't compile under VC6, it's not a valid C++ program. Programmers these days have it easy when it comes to obtaining specs. Newer languages like C#, Java, Python, Ruby, etc. all have their documentation available for free from the vendors' web sites. Older languages and platforms often have standards controlled by standards bodies that demand payment for specs, but even that shouldn't be a deterrent: the C++ standard is available from ISO for $30 (and why am I the only person I know who has a copy?). Programming is hard enough even when you do know the language. If you don't, I don't see how you have a chance. What do the rest of you think? Am I right, or should we all be content with the typical level of programming language expertise? Update: Several great comments here. Thanks. A couple of people hit on something that I didn't think about: What really irks me is not the lack of knowledge, but the lack of curiosity and willingness to learn. It seems some people don't have any time to hone their craft, but they have plenty of time to write lots of bad code. And I don't expect people to be able to recite a list of keywords or EBNF expressions, but I do expect that when they see some code, they should have some inkling of what it does. Few people have complete knowledge of every dark corner of their language or platform, but everyone should at least know enough that when they see something unfamiliar, they will know how to get whatever additional information they need to understand it.

    Read the article

  • Creating a Ruby method that pads an Array

    - by CJ Johnson
    I'm working on creating a method that pads an array, and accepts 1. a desired value and 2. an optional string/integer value. Desired_size reflects the desired number of elements in the array. If a string/integer is passed in as the second value, this value is used to pad the array with extra elements. I understand there is a 'fill' method that can shortcut this - but that would be cheating for the homework I'm doing. The issue: no matter what I do, only the original array is returned. I started here: class Array def pad(desired_size, value = nil) desired_size >= self.length ? return self : (desired_size - self.length).times.do { |x| self << value } end end test_array = [1, 2, 3] test_array.pad(5) From what I researched the issue seemed to be around trying to alter self's array, so I learned about .inject and gave that a whirl: class Array def pad(desired_size, value = nil) if desired_size >= self.length return self else (desired_size - self.length).times.inject { |array, x| array << value } return array end end end test_array = [1, 2, 3] test_array.pad(5) The interwebs tell me the problem might be with any reference to self so I wiped that out altogether: class Array def pad(desired_size, value = nil) array = [] self.each { |x| array << x } if desired_size >= array.length return array else (desired_size - array.length).times.inject { |array, x| array << value } return array end end end test_array = [1, 2, 3] test_array.pad(5) I'm very new to classes and still trying to learn about them. Maybe I'm not even testing them the right way with my test_array? Otherwise, I think the issue is I get the method to recognize the desired_size value that's being passed in. I don't know where to go next. Any advice would be appreciated. Thanks in advance for your time.

    Read the article

  • display base64 image in html

    - by Christopher
    Having trouble displaying a base64 image inline. Can someone point me in the right direction? <!DOCTYPE html> <html> <head> <title>Display Image</title> </head> <body> <img style='display:block; width:100px;height:100px;' id='base64image' src='data:image/jpeg;base64, LzlqLzRBQ...<!-- base64 data -->' /> </body>

    Read the article

  • How do I keep my branches up to date with the 'default' branch under Mercurial?

    - by Chad Johnson
    Let's say I have the following workflow with Mercurial: stable (clone on server) default (branch) development (clone on server) default (branch) bugs (branch) developer1 (clone on local machine) developer2 (clone on local machine) developer3 (clone on local machine) feature1 (branch) developer3 (clone on local machine) feature2 (branch) developer1 (clone on local machine) developer2 (clone on local machine) My main line of development which is always in a release ready state is 'default'. So the 'default' branch in the 'development' clone is always release-ready. Now suppose I'm developer1 working on feature2. And let's say also that feature2 takes several months. It's pretty obvious that I'm going to want to keep my 'feature2' branch up to date with the 'default' branch. Does this make sense? How would I go about doing this with Mercurial?

    Read the article

  • PHP: How can I eliminate quotes around output from CSV file?

    - by brian johnson
    This code: <?php $curl=curl_init(); curl_setopt ($curl,CURLOPT_URL,"http://download.finance.yahoo.com/d/quotes.csv?s=XIN&f=l1c1p2rj1y&e=.csv"); curl_setopt ($curl,CURLOPT_HEADER,0); ob_start(); curl_exec ($curl); curl_close ($curl); $data=ob_get_clean(); $data = explode(",",$data); foreach ($data as $results) echo "<td>$results</td>"; ?> yields these results in my browser: 2.80 +0.02 "+0.72%" 1.85 204.2M 1.44 How can I have this PHP code above eliminate the quotations around the "+0.72%" so the end result is just: 0.72% ?

    Read the article

  • Is there a way to force a user to select an autocomplete value before they can submit the form?

    - by Randy Johnson
    I am using the jqueryui autocomplete feature to allow the user to select their location. I need to make sure they select a location from the autocomplete before they can submit the form. I don't want them to be able to submit the form before they select a value. My solution is after they submit make sure that the value found is in the database. The other solution would be that when they click submit or after they leave the location box and go to another field to submit the entry via ajax to ensure it is valid if not show an error and do not let them submit the form. I was wondering if there was something easier I could do, or if there is something more elegant. I realize they have to be able to type something into the box to get the autocomplete to work, so I could force them to select a value from the autocomplete because it is not a select box, so it seems that my above solutions would be the best way to go. Thoughts?

    Read the article

  • gwtQuery's outerWidth(true) and IE8 not working without putting a delay

    - by Christopher
    I recently came across an odd behavior when trying to calculate the width (with margins) of an element using gwtQuery. The goal is to get the width (including padding, borders and margins) of a given element as a child of a certain parent. This parent may define specific CSS rules for some children so I clone it, add my element to this parent, call .outerWidth(true) to get the width and finally remove the clone from the parent. It works fine on Chrome, Firefox and IE 10, but randomly fails (outputs 0) on IE 8. However I noticed that if I put a "sleep" between the moment I add the element to the DOM and the moment I get the outer width, it always succeeds. I obviously don't want to keep that sleep. So my question is does anyone has any insights on how to work around this behavior or even a better way of achieving the same goal? Thank you! Here's a code snippet private Integer computeTabWidth(IsWidget tab) { GQuery $tab = $("<li></li>").append($(tab).clone()); $(containerPanel).append($tab); // IE 8 debug. sleep(100); Integer tabWidth = $tab.outerWidth(true); $tab.remove(); return tabWidth; } private void sleep(int i) { long time = new Date().getTime() + i; while (time > new Date().getTime()); }

    Read the article

  • Why use a Rails-like deployment mechanism over 'git pull' for releasing?

    - by Chad Johnson
    To release my centralized webapp, I COULD have a vhost pointed to some directory and then just do a 'git pull' when I want to release, updating the files. But Rails has a different deployment mechanism: it copies files to a subdirectory and then points a symlink ('current') to that new subdirectory. I understand that it probably more acceptable to do a Rails-like deployment because the release is built in some directory, and then the symlink is pointed to that directory, so this is much faster, and it's less likely that users would experience weird issues while a release is happening. Are there any other advantages to the Rails approach? Or, is a 'git pull' approach actually more widely accepted?

    Read the article

  • C# Retrieving Data From XML File

    - by Christopher MacKinnon
    I seem to be having a problem with retrieving XML values with C#, which I know it is due to my very limited knowledge of C# and .XML. I was given the following XML file <PowerBuilderRunTimes> <PowerBuilderRunTime> <Version>12</Version> <Files> <File>EasySoap110.dll</File> <File>exPat110.dll</File> <File>pbacc110.dll</File> </File> </PowerBuilderRunTime> </PowerBuilderRunTimes> I am to process the XML file and make sure that each of the files in the exist in the folder (that's the easy part). It's the processing of the XML file that I have having a hard time with. Here is what I have done thus far: var runtimeXml = File.ReadAllText(string.Format("{0}\\{1}", configPath, Resource.PBRuntimes)); var doc = XDocument.Parse(runtimeXml); var topElement = doc.Element("PowerBuilderRunTimes"); var elements = topElement.Elements("PowerBuilderRunTime"); foreach (XElement section in elements) { //pbVersion is grabbed earlier. It is the version of PowerBuilder if( section.Element("Version").Value.Equals(string.Format("{0}", pbVersion ) ) ) { var files = section.Elements("Files"); var fileList = new List<string>(); foreach (XElement area in files) { fileList.Add(area.Element("File").Value); } } } My issue is that the String List is only ever populated with one value, "EasySoap110.dll", and everything else is ignored. Can someone please help me, as I am at a loss.

    Read the article

  • Mass update of data in sql from int to varchar

    - by Christopher Kelly
    we have a large table (5608782 rows and growing) that has 3 columns Zip1,Zip2, distance all columns are currently int, we would like to convert this table to use varchars for international usage but need to do a mass import into the new table convert zip < 5 digits to 0 padded varchars 123 becomes 00123 etc. is there a way to do this short of looping over each row and doing the translation programmaticly?

    Read the article

  • Tracking DB changes with Zend Framework?

    - by Chad Johnson
    I am trying to decide between the Zend Framework and Ruby On Rails for my web application. If I go with ZF, I need the following: A way to incrementally track changes to my database, as with RoR's migration feature (001_something.sql, 002_something_else.sql). A place to put SQL for the next release of my software. At work in our custom PHP solution, we just have release.sql, which gets run, archived, and blanked out upon release. ZF has Zend_Db_Schema_Manager, which does the same thing, but I'm not interested as its not official, complete, or maintained. Is there an official mechanism that ZF provides for doing something similar to what I described? EDIT I ended up going with Rails. Nothing compares.

    Read the article

  • Connecting a PHP front-end to a back-end java service

    - by christopher-mccann
    I am currently using various back-end services and I want to use PHP to simply query these services and perform the final page construction. These services could be coded in any number of programming langauges such as Erlang, Java, Python etc. However I am unsure of the best way to actually interface the back-end services with the web app. Requests to these services would be both synchronous and asynchronous. Would I use something like SOAP or JSON-RPC?? Any help greatly appreciated.

    Read the article

  • Reference book on Ruby on Rails social network site for novices

    - by Christopher
    Hey, so I am a novice programmer who has only worked with HTML, CSS, and a touch of Java a couple of years ago. I am looking to try to get a social network site up and running on Ruby on Rails and was looking at RailsSpace: Building a Social Networking Website with Ruby on Rails (Addison-Wesley Professional Ruby Series) - Paperback (July 30, 2007) by Michael Hartl. This was published in 2007, however, and the newer reviews say it is not very helpful. Does anyone know if there are any new publications out there that walk you through building a social network site while teaching you the code(rather than just using a out of the box program)? Thanks

    Read the article

< Previous Page | 16 17 18 19 20 21 22 23 24 25 26 27  | Next Page >