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• IPHONE DEVELOPMENT PROFILE EXPIRED - I TRIED EVERYTHING AND YES, I READ THE DOCS

  - by theiphoneguy

  I really combed this site and others. I read and re-read the related links here and the Apple docs. I'm sorry, but either I am obviously missing something right under my nose, or this Apple profile/certificate stuff is a bit convoluted. Here it is: I have a product in the App Store. I have updated it several times and users like it. My development profile recently expired just when I was improving the app for its next release. I can run the app in the simulator. I can compile and put the distribution build on my iPhone just fine. I went to the Apple portal and renewed the development profile. I downloaded it and installed it in Xcode. I see it in the Organize window. I see it on my iPhone. I CANNOT put the debug build on my iPhone to debug or run with Instruments. The message is that either there is not a valid signed profile or it is untrusted. I subsequently tried to download and install the certificate to my Mac's keychain. Still no success. I checked the code signing section of Project settings and also for the target and the root. All appears to indicate that it is using the expected development profile for debug. Yes, I had deleted the old profile from my iPhone, from the Organizer. I cleaned the Xcode cache and all targets. I have done all of this several times and in varying sequences to try to cover every possibility. I am ready to do anything to be able to debug with Instruments in order to check for leaks or high memory usage. Even though the distribution compile runs fine on my iPhone and plays well with other running processes, I will not release anything without a leaks/memory test. Any ideas will be appreciated. If I missed something obvious, please forgive me - it was not due to just posting a question without searching for similar postings. Thanks!

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• Simple calculator app crashes when a third number key is punched.

  - by Justin

  Hi , I am a newbie to the iphone app world. So I thought I try my luck with a calculator app. Unfortunately I am running into an issue where if I press a third key in the calculator the app crashes. Sometimes I get this error EXC_BAD_ACCESS. Here is a code in my CalculatorViewController.m file. #import "CalculatorViewController.h" @implementation CalculatorViewController @synthesize screenText; - (IBAction)buttonPressed:(id)sender { NSString *title = [sender titleForState:UIControlStateNormal]; [self collect:title]; } - (void)collect:(NSString *)digitz { NSString * newText = nil; if ([digitz isEqualToString:@"+"]) { [self add:result]; big_digit = nil; } else if ([digitz isEqualToString:@"+"]) { [self sub:result]; } else if ([digitz isEqualToString:@"x"]) { [self multiply:result]; } else if ([digitz isEqualToString:@"="]) { [self equate:result]; } else { if (big_digit != nil && [big_digit isEqualToString:@"0"] == FALSE) big_digit = [big_digit stringByAppendingFormat:@"%@",digitz]; else big_digit = (NSMutableString *) digitz; result = (int) big_digit; newText = [[NSString alloc] initWithFormat: @"%@",big_digit]; } screenText.text = newText; [newText release]; } - (void)add:(int)res { NSString * newText = nil; ans = ans + res; newText = [[NSString alloc] initWithFormat: @"%@",ans]; screenText.text = newText; [newText release]; } Can anyone spot an obvious issue here. Here is the respective header file too. #import <UIKit/UIKit.h> @interface CalculatorViewController : UIViewController { UILabel *screenText; int number; int result; int ans; //NSString *big_digit; NSMutableString * big_digit ; } @property (nonatomic, retain) IBOutlet UILabel *screenText; - (IBAction)buttonPressed:(id)sender; - (void)collect:(NSString *)digitz; - (void)add:(int)num; - (void)sub:(int)num; - (void)multiply:(int)num; - (void)equate:(int)num; @end

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• Python/Biomolecular Physics- Trying to code a simple stochastic simulation of a system exhibiting co

  - by user359597

  *edited 6/17/10 I'm trying to understand how to improve my code (make it more pythonic). Also, I'm interested in writing more intuitive 'conditionals' that would describe scenarios that are commonplace in biochemistry. The conditional criteria in the below program is explained in Answer #2, but I am not satisfied with it- it is correct, but isn't obvious and isn't easy to implement for more complicated conditional scenarios. Ideas welcome. Comments/criticisms welcome. First posting experience @ stackoverflow- please comment on etiquette if needed. The code generates a list of values that are the solution to the following exercise: "In a programming language of your choice, implement Gillespie’s First Reaction Algorithm to study the temporal behaviour of the reaction A---B in which the transition from A to B can only take place if another compound, C, is present, and where C dynamically interconverts with D, as modelled in the Petri-net below. Assume that there are 100 molecules of A, 1 of C, and no B or D present at the start of the reaction. Set kAB to 0.1 s-1 and both kCD and kDC to 1.0 s-1. Simulate the behaviour of the system over 100 s." def sim(): # Set the rate constants for all transitions kAB = 0.1 kCD = 1.0 kDC = 1.0 # Set up the initial state A = 100 B = 0 C = 1 D = 0 # Set the start and end times t = 0.0 tEnd = 100.0 print "Time\t", "Transition\t", "A\t", "B\t", "C\t", "D" # Compute the first interval transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) # Loop until the end time is exceded or no transition can fire any more while t <= tEnd and transition >= 0: print t, '\t', transition, '\t', A, '\t', B, '\t', C, '\t', D t += interval if transition == 0: A -= 1 B += 1 if transition == 1: C -= 1 D += 1 if transition == 2: C += 1 D -= 1 transition, interval = transitionData(A, B, C, D, kAB, kCD, kDC) def transitionData(A, B, C, D, kAB, kCD, kDC): """ Returns nTransition, the number of the firing transition (0: A->B, 1: C->D, 2: D->C), and interval, the interval between the time of the previous transition and that of the current one. """ RAB = kAB * A * C RCD = kCD * C RDC = kDC * D dt = [-1.0, -1.0, -1.0] if RAB > 0.0: dt[0] = -math.log(1.0 - random.random())/RAB if RCD > 0.0: dt[1] = -math.log(1.0 - random.random())/RCD if RDC > 0.0: dt[2] = -math.log(1.0 - random.random())/RDC interval = 1e36 transition = -1 for n in range(len(dt)): if dt[n] > 0.0 and dt[n] < interval: interval = dt[n] transition = n return transition, interval if __name__ == '__main__': sim()

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• ASP.NET MVC : Good Replacement for User Control?

  - by David Lively

  I found user controls to be incredibly useful when working with ASP.NET webforms. By encapsulating the code required for displaying a control with the markup, creation of reusable components was very straightforward and very, very useful. While MVC provides convenient separation of concerns, this seems to break encapsulation (ie, you can add a control without adding or using its supporting code, leading to runtime errors). Having to modify a controller every time I add a control to a view seems to me to integrate concerns, not separate them. I'd rather break the purist MVC ideology than give up the benefits of reusable, packaged controls. I need to be able to include components similar to webforms user controls throughout a site, but not for the entire site, and not at a level that belongs in a master page. These components should have their own code not just markup (to interact with the business layer), and it would be great if the page controller didn't need to know about the control. Since MVC user controls don't have codebehind, I can't see a good way to do this. Update FINALLY, a good (and, in retrospect, obvious) way to accomplish this. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; namespace K.ObjectModel.Controls { public class TestControl : ViewUserControl { protected override void Render(System.Web.UI.HtmlTextWriter writer) { writer.Write("Hello World"); base.Render(writer); } } } Create a new class which inherits ViewUserControl Override the .Render() method as shown above. Register the control via its associated ASCX as you would in a webForm: <%@ Register TagName="tn" TagPrefix="k" Src="~/Views/Navigation/LeftBar.ascx"%> Use the corresponding tag in whatever view or master page that you need: <k:tn runat="server"/> Make sure your .ascx inherits your new control: <%@ Control Language="C#" Inherits="K.ObjectModel.Controls.TestControl" %> Voila, you're up and running. This is tested with ASP.NET MVC 2, VS 2010 and .NET 4.0. Your custom tag references the ascx partial view, which inherits from the TestControl class. The control then overrides the Render() method, which is called to render the view, giving you complete control over the process from tag to output. Why does everyone try to make this so much harder than it has to be?

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• Infinite loop when adding a row to a list in a class in python3

  - by Margaret

  I have a script which contains two classes. (I'm obviously deleting a lot of stuff that I don't believe is relevant to the error I'm dealing with.) The eventual task is to create a decision tree, as I mentioned in this question. Unfortunately, I'm getting an infinite loop, and I'm having difficulty identifying why. I've identified the line of code that's going haywire, but I would have thought the iterator and the list I'm adding to would be different objects. Is there some side effect of list's .append functionality that I'm not aware of? Or am I making some other blindingly obvious mistake? class Dataset: individuals = [] #Becomes a list of dictionaries, in which each dictionary is a row from the CSV with the headers as keys def field_set(self): #Returns a list of the fields in individuals[] that can be used to split the data (i.e. have more than one value amongst the individuals def classified(self, predicted_value): #Returns True if all the individuals have the same value for predicted_value def fields_exhausted(self, predicted_value): #Returns True if all the individuals are identical except for predicted_value def lowest_entropy_value(self, predicted_value): #Returns the field that will reduce <a href="http://en.wikipedia.org/wiki/Entropy_%28information_theory%29">entropy</a> the most def __init__(self, individuals=[]): and class Node: ds = Dataset() #The data that is associated with this Node links = [] #List of Nodes, the offspring Nodes of this node level = 0 #Tree depth of this Node split_value = '' #Field used to split out this Node from the parent node node_value = '' #Value used to split out this Node from the parent Node def split_dataset(self, split_value): fields = [] #List of options for split_value amongst the individuals datasets = {} #Dictionary of Datasets, each one with a value from fields[] as its key for field in self.ds.field_set()[split_value]: #Populates the keys of fields[] fields.append(field) datasets[field] = Dataset() for i in self.ds.individuals: #Adds individuals to the datasets.dataset that matches their result for split_value datasets[i[split_value]].individuals.append(i) #<---Causes an infinite loop on the second hit for field in fields: #Creates subnodes from each of the datasets.Dataset options self.add_subnode(datasets[field],split_value,field) def add_subnode(self, dataset, split_value='', node_value=''): def __init__(self, level, dataset=Dataset()): My initialisation code is currently: if __name__ == '__main__': filename = (sys.argv[1]) #Takes in a CSV file predicted_value = "# class" #Identifies the field from the CSV file that should be predicted base_dataset = parse_csv(filename) #Turns the CSV file into a list of lists parsed_dataset = individual_list(base_dataset) #Turns the list of lists into a list of dictionaries root = Node(0, Dataset(parsed_dataset)) #Creates a root node, passing it the full dataset root.split_dataset(root.ds.lowest_entropy_value(predicted_value)) #Performs the first split, creating multiple subnodes n = root.links[0] n.split_dataset(n.ds.lowest_entropy_value(predicted_value)) #Attempts to split the first subnode.

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• When to call glEnable(GL_FRAMEBUFFER_SRGB)?

  - by Steven Lu

  I have a rendering system where I draw to an FBO with a multisampled renderbuffer, then blit it to another FBO with a texture in order to resolve the samples in order to read off the texture to perform post-processing shading while drawing to the backbuffer (FBO index 0). Now I'd like to get some correct sRGB output... The problem is the behavior of the program is rather inconsistent between when I run it on OS X and Windows and this also changes depending on the machine: On Windows with the Intel HD 3000 it will not apply the sRGB nonlinearity but on my other machine with a Nvidia GTX 670 it does. On the Intel HD 3000 in OS X it will also apply it. So this probably means that I'm not setting my GL_FRAMEBUFFER_SRGB enable state at the right points in the program. However I can't seem to find any tutorials that actually tell me when I ought to enable it, they only ever mention that it's dead easy and comes at no performance cost. I am currently not loading in any textures so I haven't had a need to deal with linearizing their colors yet. To force the program to not simply spit back out the linear color values, what I have tried is simply comment out my glDisable(GL_FRAMEBUFFER_SRGB) line, which effectively means this setting is enabled for the entire pipeline, and I actually redundantly force it back on every frame. I don't know if this is correct or not. It certainly does apply a nonlinearization to the colors but I can't tell if this is getting applied twice (which would be bad). It could apply the gamma as I render to my first FBO. It could do it when I blit the first FBO to the second FBO. Why not? I've gone so far as to take screen shots of my final frame and compare raw pixel color values to the colors I set them to in the program: I set the input color to RGB(1,2,3) and the output is RGB(13,22,28). That seems like quite a lot of color compression at the low end and leads me to question if the gamma is getting applied multiple times. I have just now gone through the sRGB equation and I can verify that the conversion seems to be only applied once as linear 1/255, 2/255, and 3/255 do indeed map to sRGB 13/255, 22/255, and 28/255 using the equation 1.055*C^(1/2.4)+0.055. Given that the expansion is so large for these low color values it really should be obvious if the sRGB color transform is getting applied more than once. So, I still haven't determined what the right thing to do is. does glEnable(GL_FRAMEBUFFER_SRGB) only apply to the final framebuffer values, in which case I can just set this during my GL init routine and forget about it hereafter?

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• Why is FLD1 loading NaN instead?

  - by Bernd Jendrissek

  I have a one-liner C function that is just return value * pow(1.+rate, -delay); - it discounts a future value to a present value. The interesting part of the disassembly is 0x080555b9 : neg %eax 0x080555bb : push %eax 0x080555bc : fildl (%esp) 0x080555bf : lea 0x4(%esp),%esp 0x080555c3 : fldl 0xfffffff0(%ebp) 0x080555c6 : fld1 0x080555c8 : faddp %st,%st(1) 0x080555ca : fxch %st(1) 0x080555cc : fstpl 0x8(%esp) 0x080555d0 : fstpl (%esp) 0x080555d3 : call 0x8051ce0 0x080555d8 : fmull 0xfffffff8(%ebp) While single-stepping through this function, gdb says (rate is 0.02, delay is 2; you can see them on the stack): (gdb) si 0x080555c6 30 return value * pow(1.+rate, -delay); (gdb) info float R7: Valid 0x4004a6c28f5c28f5c000 +41.68999999999999773 R6: Valid 0x4004e15c28f5c28f6000 +56.34000000000000341 R5: Valid 0x4004dceb851eb851e800 +55.22999999999999687 R4: Valid 0xc0008000000000000000 -2 =R3: Valid 0x3ff9a3d70a3d70a3d800 +0.02000000000000000042 R2: Valid 0x4004ff147ae147ae1800 +63.77000000000000313 R1: Valid 0x4004e17ae147ae147800 +56.36999999999999744 R0: Valid 0x4004efb851eb851eb800 +59.92999999999999972 Status Word: 0x1861 IE PE SF TOP: 3 Control Word: 0x037f IM DM ZM OM UM PM PC: Extended Precision (64-bits) RC: Round to nearest Tag Word: 0x0000 Instruction Pointer: 0x73:0x080555c3 Operand Pointer: 0x7b:0xbff41d78 Opcode: 0xdd45 And after the fld1: (gdb) si 0x080555c8 30 return value * pow(1.+rate, -delay); (gdb) info float R7: Valid 0x4004a6c28f5c28f5c000 +41.68999999999999773 R6: Valid 0x4004e15c28f5c28f6000 +56.34000000000000341 R5: Valid 0x4004dceb851eb851e800 +55.22999999999999687 R4: Valid 0xc0008000000000000000 -2 R3: Valid 0x3ff9a3d70a3d70a3d800 +0.02000000000000000042 =R2: Special 0xffffc000000000000000 Real Indefinite (QNaN) R1: Valid 0x4004e17ae147ae147800 +56.36999999999999744 R0: Valid 0x4004efb851eb851eb800 +59.92999999999999972 Status Word: 0x1261 IE PE SF C1 TOP: 2 Control Word: 0x037f IM DM ZM OM UM PM PC: Extended Precision (64-bits) RC: Round to nearest Tag Word: 0x0020 Instruction Pointer: 0x73:0x080555c6 Operand Pointer: 0x7b:0xbff41d78 Opcode: 0xd9e8 After this, everything goes to hell. Things get grossly over or undervalued, so even if there were no other bugs in my freeciv AI attempt, it would choose all the wrong strategies. Like sending the whole army to the arctic. (Sigh, if only I were getting that far.) I must be missing something obvious, or getting blinded by something, because I can't believe that fld1 should ever possibly fail. Even less that it should fail only after a handful of passes through this function. On earlier passes the FPU correctly loads 1 into ST(0). The bytes at 0x080555c6 definitely encode fld1 - checked with x/... on the running process. What gives?

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• Missing parameter error after running MySql query

  - by annelie

  Hello, I'm completely new to MySql and haven't used SqlDataSource with UpdateParameters before, so I'm probably missing something very obvious. When trying to update a record, the update does happen but then throws an error saying "'id' parameter is missing at the statement". So the query works and the database gets updated as it should, but an error is thrown afterwards. These are the update parameters: <UpdateParameters> <asp:Parameter Name="business_name" Type="string" Size="256" /> <asp:Parameter Name="addr_line_1" Type="string" Size="256" /> <asp:Parameter Name="addr_line_2" Type="string" Size="256" /> <asp:Parameter Name="addr_line_3" Type="string" Size="256" /> <asp:Parameter Name="postcode" Type="string" Size="32" /> <asp:Parameter Name="county" Type="string" Size="128" /> <asp:Parameter Name="town_city" Type="string" Size="256" /> <asp:Parameter Name="tl_url" Type="string" Size="256" /> <asp:Parameter Name="customer_id" Type="string" Size="16" /> <asp:Parameter Name="region_id" Type="Int16" /> <asp:Parameter Name="description" Type="string" Size="1024" /> <asp:Parameter Name="approval_status" Type="string" Size="1" /> <asp:Parameter Name="tl_user_name" Type="string" Size="256" /> <asp:Parameter Name="phone" Type="string" Size="50" /> <asp:Parameter Name="uploaders_own" Type="Int16" /> </UpdateParameters> Here's the update statement: UPDATE myTable SET business_name = ?, addr_line_1 = ?, addr_line_2 = ?, addr_line_3 = ?, postcode = ?, county = ?, town_city = ?, tl_url = ?, customer_id = ?, region_id = ?, description = ?, approval_status = ?, tl_user_name = ?, phone = ?, uploaders_own = ? WHERE id = " + id Here's the stack trace: [InvalidOperationException: 'id' parameter is missing at the statement] CoreLab.MySql.r.a() +775 CoreLab.MySql.r.a(Int32& A_0, ArrayList& A_1) +448 CoreLab.MySql.x.e() +398 CoreLab.MySql.x.o() +89 CoreLab.MySql.MySqlCommand.a(CommandBehavior A_0, IDisposable A_1, Int32 A_2, Int32 A_3) +1306 CoreLab.Common.DbCommandBase.ExecuteDbDataReader(CommandBehavior behavior) +310 System.Data.Common.DbCommand.ExecuteReader() +12 CoreLab.Common.DbCommandBase.ExecuteNonQuery() +64 System.Web.UI.WebControls.SqlDataSourceView.ExecuteDbCommand(DbCommand command, DataSourceOperation operation) +386 System.Web.UI.WebControls.SqlDataSourceView.ExecuteUpdate(IDictionary keys, IDictionary values, IDictionary oldValues) +325 System.Web.UI.DataSourceView.Update(IDictionary keys, IDictionary values, IDictionary oldValues, DataSourceViewOperationCallback callback) +92 System.Web.UI.WebControls.DetailsView.HandleUpdate(String commandArg, Boolean causesValidation) +837 System.Web.UI.WebControls.DetailsView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup) +509 System.Web.UI.WebControls.DetailsView.OnBubbleEvent(Object source, EventArgs e) +95 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 System.Web.UI.WebControls.DetailsViewRow.OnBubbleEvent(Object source, EventArgs e) +113 System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37 System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e) +118 System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) +135 System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +175 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565 Does anyone know what I'm doing wrong? Thanks, Annelie

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• AJAX, same-origin Policy and working XML Requests

  - by Joern

  Hello guys, so, currently I develop Widgets for Smartphones and am going a bit more advanced into fields of data exchange between client and server applications. My problem is: For my current project I want my client file to request data from a PHP script with the help of AJAX XmlHttpRequest and the POST method: function xmlRequestNotes() { var parameter = 'p=1234'; xmlhttp = new XMLHttpRequest(); xmlhttp.open("POST", url, true); // Http Header xmlhttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); xmlhttp.setRequestHeader("Content-length", parameter.length); xmlhttp.setRequestHeader("Connection", "close"); xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { json = JSON.parse(xmlhttp.responseText); // Doing Stuff with the Response } }; xmlhttp.send(parameter); } This works perfectly fine on my local server set up in XAMPP and the local Widget emulator. But if it gets onto the device (also with access to the target network) I receive the 101 Network Error. And as far as I have read, this is due to the "Same-Origin Policy" of XmlHttpRequests? My problem is to really understand that. Although the idea of this policy is clear to me, I'm a bit confused by the fact that another XmlHttpRequest for a Yahoo Weather XML Feed works fine. Now, could anyone be so helpful to enlighten me? Here is the request that returns a city name from Yahoo's weather feed: function getCityName() { xmlhttp = new XMLHttpRequest(); xmlhttp.open("GET", "http://weather.yahooapis.com/forecastrss?w=645458&u=c", true); xmlhttp.onreadystatechange = function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { xmlhttp.responseXML; var yweather = "http://xml.weather.yahoo.com/ns/rss/1.0"; alert(xmlhttp.responseXML.getElementsByTagNameNS(yweather, "location")[0].getAttribute("city")); } }; xmlhttp.send(null); } Obvious differences are the POST and GET methods for once, but seeing that the Same-Origin Policy takes effect no matter what method, I can't really make much sense of it. Why does the latter request work but not the first? I would really appreciate some help here. Greetings and a merry Christmas to you guys!

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• Searching in Ruby on Rails - How do I search on each word entered and not the exact string?

  - by bgadoci

  I have built a blog application w/ ruby on rails and I am trying to implement a search feature. The blog application allows for users to tag posts. The tags are created in their own table and belong_to :post. When a tag is created, so is a record in the tag table where the name of the tag is tag_name and associated by post_id. Tags are strings. I am trying to allow a user to search for any word tag_name in any order. Here is what I mean. Lets say a particular post has a tag that is 'ruby code controller'. In my current search feature, that tag will be found if the user searches for 'ruby', 'ruby code', or 'ruby code controller'. It will not be found if the user types in 'ruby controller'. Essentially what I am saying is that I would like each word entered in the search to be searched for, not necessarily the 'string' that is entered into the search. I have been experimenting with providing multiple textfields to allow the user to type in multiple words, and also have been playing around with the code below, but can't seem to accomplish the above. I am new to ruby and rails so sorry if this is an obvious question and prior to installing a gem or plugin I thought I would check to see if there was a simple fix. Here is my code: View: /views/tags/index.html.erb <% form_tag tags_path, :method => 'get' do %> <p> <%= text_field_tag :search, params[:search], :class => "textfield-search" %> <%= submit_tag "Search", :name => nil, :class => "search-button" %> </p> <% end %> TagsController def index @tags = Tag.search(params[:search]).paginate :page => params[:page], :per_page => 5 @tagsearch = Tag.search(params[:search]) @tag_counts = Tag.count(:group => :tag_name, :order => 'count_all DESC', :limit => 100) respond_to do |format| format.html # index.html.erb format.xml { render :xml => @tags } end end Tag Model class Tag < ActiveRecord::Base belongs_to :post validates_length_of :tag_name, :maximum=>42 validates_presence_of :tag_name def self.search(search) if search find(:all, :order => "created_at DESC", :conditions => ['tag_name LIKE ?', "%#{search}%"]) else find(:all, :order => "created_at DESC") end end end

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• markdown to HTML with customised WMD editor

  - by spirytus

  For my application I customized slightly the way WMD behaves so when user enters empty lines, these are reflected in HTML output as <br />'s. Now I came to a point when I should store it somewhere at backend and so after going thru SO posts for a while I'm not sure what is the best way to do it. I have few options and if you could point out which their pros/cons that would be much appreciated. send to server and store as markdown rather than HTML. To me obvious advantage would be keeping exactly same formatting as user originally entered. But then how can I convert it back to HTML for display to a client? It seems very troublesome to convert it on client side as even if it would be possible what would happen if JS would be disabled? If I wanted to do it on the server, then standard server side implementations of markup to HTML might be resource expensive. Would that be an issue in your opinion? Even if it wouldn't be the case then as I mentioned my WMD implementation is customised and those server side solutions wouldn't probably do the right conversion to markdown anyway and there always would be a risk that something would convert wrong. Send to server as converted HTML. Same as above.. conversion on client side would be difficult, server side same with possibility of getting it wrong. send original markdown and converted HTML and store both. No performance issues related to converting markdown to HTML on client side, nor on server side. Users would have always same markdown they originally entered and same HTML they originally saw in preview (possibly sanitized in php though). It would have to take twice that much storage space though and that is my biggest worry. I tend to lean towards 3rd solution as it seems simplest, but there is a worry of doubled storage space needed for this solution. Please bear in mind that my implementation of WMD is slightly modified and also I'm going with PHP/MySql server side implementation. So apart from 3 options I listed above, are there any other possible solutions to my problem? Did I miss anything important that would make one of the options above better then the rest? And what other pros/cons would apply to each solution I listed? Also how is it implemented on SO? I read somwhere that they using option 3, and so if its good enough for SO would be good enough for me :) but not sure if its true anyway, so how is it done? Also please forgive me, but at least for once I got to say that StackOverflow IS THE BEST DAMN RESOURCE ON THE WEB and I truly appreciate all the people trying to help others here! The site and users here are simply amazing!

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• Getting key/value pairs from plist-style xml using simplexml in php

  - by Anthony

  Here is an example bit from the xml file: <array> <dict> <key>Name</key> <string>Joe Smith</string> <key>Type</key> <string>Profile</string> <key>Role</key> <string>User</string> <key>Some Number</key> <integer>1</integer> <key>Some Boolean</key> <true/> </dict> </array> I have two separate goals. The first is to extract an array from the dictnode that would look like: [Name] => Joe Smith [Type] => Profile [Role] => User [Some Number] => 1 [Some Boolean] => true It's not crucial that the boolean be included, so if that adds too much complexity, I'd rather just know how to deal with the others for now. The second goal is to be able to select the value node (<string>, <integer>,etc) so that I can change the value. I would need to select it based on the text value of the preceding key element. I think the following XPath should work: //key[.=$keyname]/following-sibling[1] But I'm not sure. Basically, this whole system that Apple uses seems logical, but totally contrary to the XML is supposed to work. If I ran the world, the original XML would look more like: <dict type="array"> <value key="Name" type="string">Joe Smith</value> <value key="Type" type="string">Profile</value> <value key="Role type="string">User</value> <value key="Some Number" type="integer">1</value> <value key="Some Boolean" type="boolean">true</value> </dict> But since it is fairly logical, I am wondering if I'm missing some obvious way of handling it.

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• Mocking methods that call other methods Still hit database.Can I avoid it?

  - by devnet247

  Hi, It has been decided to write some unit tests using moq etc..It's lots of legacy code c# (this is beyond my control so cannot answer the whys of this) Now how do you cope with a scenario when you dont want to hit the database but you indirectly still hit the database? This is something I put together it's not the real code but gives you an idea. How would you deal with this sort of scenario? Basically calling a method on a mocked interface still makes a dal call as inside that method there are other methods not part of that interface?Hope it's clear [TestFixture] public class Can_Test_this_legacy_code { [Test] public void Should_be_able_to_mock_login() { var mock = new Mock<ILoginDal>(); User user; var userName = "Jo"; var password = "password"; mock.Setup(x => x.login(It.IsAny<string>(), It.IsAny<string>(),out user)); var bizLogin = new BizLogin(mock.Object); bizLogin.Login(userName, password, out user); } } public class BizLogin { private readonly ILoginDal _login; public BizLogin(ILoginDal login) { _login = login; } public void Login(string userName, string password, out User user) { //Even if I dont want to this will call the DAL!!!!! var bizPermission = new BizPermission(); var permissionList = bizPermission.GetPermissions(userName); //Method I am actually testing _login.login(userName,password,out user); } } public class BizPermission { public List<Permission>GetPermissions(string userName) { var dal=new PermissionDal(); var permissionlist= dal.GetPermissions(userName); return permissionlist; } } public class PermissionDal { public List<Permission> GetPermissions(string userName) { //I SHOULD NOT BE GETTING HERE!!!!!! return new List<Permission>(); } } public interface ILoginDal { void login(string userName, string password,out User user); } public interface IOtherStuffDal { List<Permission> GetPermissions(); } public class Permission { public int Id { get; set; } public string Name { get; set; } } Any suggestions? Am I missing the obvious? Is this Untestable code? Very very grateful for any suggestions.

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• IPhone Development Profile Expired

  - by theiphoneguy

  I really combed this site and others. I read and re-read the related links here and the Apple docs. I'm sorry, but either I am obviously missing something right under my nose, or this Apple profile/certificate stuff is a bit convoluted. Here it is: I have a product in the App Store. I have updated it several times and users like it. My development profile recently expired just when I was improving the app for its next release. I can run the app in the simulator. I can compile and put the distribution build on my iPhone just fine. I went to the Apple portal and renewed the development profile. I downloaded it and installed it in Xcode. I see it in the Organize window. I see it on my iPhone. I CANNOT put the debug build on my iPhone to debug or run with Instruments. The message is that either there is not a valid signed profile or it is untrusted. I subsequently tried to download and install the certificate to my Mac's keychain. Still no success. I checked the code signing section of Project settings and also for the target and the root. All appears to indicate that it is using the expected development profile for debug. Yes, I had deleted the old profile from my iPhone, from the Organizer. I cleaned the Xcode cache and all targets. I have done all of this several times and in varying sequences to try to cover every possibility. I am ready to do anything to be able to debug with Instruments in order to check for leaks or high memory usage. Even though the distribution compile runs fine on my iPhone and plays well with other running processes, I will not release anything without a leaks/memory test. Any ideas will be appreciated. If I missed something obvious, please forgive me - it was not due to just posting a question without searching for similar postings. Thanks!

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• Specializating a template function that takes a universal reference parameter

  - by David Stone

  How do I specialize a template function that takes a universal reference parameter? foo.hpp: template<typename T> void foo(T && t) // universal reference parameter foo.cpp template<> void foo<Class>(Class && class) { // do something complicated } Here, Class is no longer a deduced type and thus is Class exactly; it cannot possibly be Class &, so reference collapsing rules will not help me here. I could perhaps create another specialization that takes a Class & parameter (I'm not sure), but that implies duplicating all of the code contained within foo for every possible combination of rvalue / lvalue references for all parameters, which is what universal references are supposed to avoid. Is there some way to accomplish this? To be more specific about my problem in case there is a better way to solve it: I have a program that can connect to multiple game servers, and each server, for the most part, calls everything by the same name. However, they have slightly different versions for a few things. There are a few different categories that these things can be: a move, an item, etc. I have written a generic sort of "move string to move enum" set of functions for internal code to call, and my server interface code has similar functions. However, some servers have their own internal ID that they communicate with, some use strings, and some use both in different situations. Now what I want to do is make this a little more generic. I want to be able to call something like ServerNamespace::server_cast<Destination>(source). This would allow me to cast from a Move to a std::string or ServerMoveID. Internally, I may need to make a copy (or move from) because some servers require that I keep a history of messages sent. Universal references seem to be the obvious solution to this problem. The header file I'm thinking of right now would expose simply this: namespace ServerNamespace { template<typename Destination, typename Source> Destination server_cast(Source && source); } And the implementation file would define all legal conversions as template specializations.

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• Which style is preferable when writing this boolean expression?

  - by Jeppe Stig Nielsen

  I know this question is to some degree a matter of taste. I admit this is not something I don't understand, it's just something I want to hear others' opinion about. I need to write a method that takes two arguments, a boolean and a string. The boolean is in a sense (which will be obvious shortly) redundant, but it is part of a specification that the method must take in both arguments, and must raise an exception with a specific message text if the boolean has the "wrong" value. The bool must be true if and only if the string is not null or empty. So here are some different styles to write (hopefully!) the same thing. Which one do you find is the most readable, and compliant with good coding practice? // option A: Use two if, repeat throw statement and duplication of message string public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name)) throw new SomeException("..."); if (!useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option B: Long expression but using only && and || public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name) || !useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option C: With == operator between booleans public void SomeMethod(bool useName, string name) { if (useName == string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option D1: With XOR operator public void SomeMethod(bool useName, string name) { if (!(useName ^ string.IsNullOrEmpty(name))) throw new SomeException("..."); // rest of method } // option D2: With XOR operator public void SomeMethod(bool useName, string name) { if (useName ^ !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } Of course you're welcome to suggest other possibilities too. Message text "..." would be something like "If 'useName' is true a name must be given, and if 'useName' is false no name is allowed".

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• Application error when drawing to SurfaceView

  - by DKDiveDude

  I'm am doing a simple coding attempt trying to draw on a SurfaceView created on my main.xml layout. I can change background color and display an icon fine, but when I try to draw I get an error. I am a newbie so obvious I am missing something, please lent a helping hint, thanks! main.xml <?xml version="1.0" encoding="utf-8"?> <SurfaceView android:id="@+id/Paper" android:layout_height="fill_parent" android:layout_width="fill_parent"> </SurfaceView> and code here; package com.example.SurfaceViewTest; import android.app.Activity; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.os.Bundle; import android.view.SurfaceHolder; import android.view.SurfaceView; public class SurfaceViewTest extends Activity implements SurfaceHolder.Callback { private SurfaceView mSurfaceView; private SurfaceHolder mSurfaceHolder; private Paint paint; private Canvas canvas; Bitmap mDrawing; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mSurfaceView = (SurfaceView) this.findViewById(R.id.Paper); mSurfaceHolder = mSurfaceView.getHolder(); mSurfaceHolder.addCallback(this); mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { // TODO Auto-generated method stub } @Override public void surfaceCreated(SurfaceHolder holder) { mSurfaceView.setBackgroundColor(Color.rgb(0, 255, 0)); //mSurfaceView.setBackgroundResource(R.drawable.icon); canvas = holder.lockCanvas(null); mDrawing = Bitmap.createBitmap(100, 100, Bitmap.Config.RGB_565); canvas.setBitmap(mDrawing); paint = new Paint(); paint.setColor(Color.rgb(255, 255,255)); canvas.drawLine(1,1,200,300, paint); holder.unlockCanvasAndPost(canvas); } @Override public void surfaceDestroyed(SurfaceHolder holder) { // TODO Auto-generated method stub } }

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• Sessions not persisting between requests

  - by klonq

  My session objects are only stored within the request scope on google app engine and I can't figure out how to persist objects between requests. The docs are next to useless on this matter and I can't find anyone who's experienced a similar problem. Please help. When I store session objects in the servlet and forward the request to a JSP using: getServletContext().getRequestDispatcher("/example.jsp").forward(request,response); Everything works like it should. But when I store objects to the session and redirect the request using: response.sendRedirect("/example/url"); The session objects are lost to the ether. In fact when I dump session key/value pairs on new requests there is absolutely nothing, session objects only appear within the request scope of servlets which create session objects. It appears to me that the objects are not being written to Memcache or Datastore. In terms of configuring sessions for my application I have set <sessions-enabled>true</sessions-enabled> In appengine-web.xml. Is there anything else I am missing? The single paragraph of documentation on sessions also notes that only objects which implement Serializable can be stored in the session between requests. I have included an example of the code which is not working below. The obvious solution is to not use redirects, and this might be ok for the example given below but some application data does need to be stored in the session between requests so I need to find a solution to this problem. EXAMPLE: The class FlashMessage gives feedback to the user from server-side operations. if (email.send()) { FlashMessage flash = new FlashMessage(FlashMessage.SUCCESS, "Your message has been sent."); session.setAttribute(FlashMessage.SESSION_KEY, flash); // The flash message will not be available in the session object in the next request response.sendRedirect(URL.HOME); } else { FlashMessage flash = new FlashMessage(FlashMessage.ERROR, FlashMessage.INVALID_FORM_DATA); session.setAttribute(FlashMessage.SESSION_KEY, flash); // The flash message is displayed without problem getServletContext().getRequestDispatcher(Templates.CONTACT_FORM).forward(request,response); } FlashMessage.java import java.io.Serializable; public class FlashMessage implements Serializable { private static final long serialVersionUID = 8109520737272565760L; // I have tried using different, default and no serialVersionUID public static final String SESSION_KEY = "flashMessage"; public static final String ERROR = "error"; public static final String SUCCESS = "success"; public static final String INVALID_FORM_DATA = "Your request failed to validate."; private String message; private String type; public FlashMessage (String type, String message) { this.type = type; this.message = message; } public String display(){ return "<div id='flash' class='" + type + "'>" + message + "</div>"; } }

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• C++ Class Access Specifier Verbosity

  - by PolyTex

  A "traditional" C++ class (just some random declarations) might resemble the following: class Foo { public: Foo(); explicit Foo(const std::string&); ~Foo(); enum FooState { Idle, Busy, Unknown }; FooState GetState() const; bool GetBar() const; void SetBaz(int); private: struct FooPartialImpl; void HelperFunction1(); void HelperFunction2(); void HelperFunction3(); FooPartialImpl* m_impl; // smart ptr FooState m_state; bool m_bar; int m_baz; }; I always found this type of access level specification ugly and difficult to follow if the original programmer didn't organize his "access regions" neatly. Taking a look at the same snippet in a Java/C# style, we get: class Foo { public: Foo(); public: explicit Foo(const std::string&); public: ~Foo(); public: enum FooState { Idle, Busy, Unknown }; public: FooState GetState() const; public: bool GetBar() const; public: void SetBaz(int); private: struct FooPartialImpl; private: void HelperFunction1(); private: void HelperFunction2(); private: void HelperFunction3(); private: FooPartialImpl* m_impl; // smart ptr private: FooState m_state; private: bool m_bar; private: int m_baz; }; In my opinion, this is much easier to read in a header because the access specifier is right next to the target, and not a bunch of lines away. I found this especially true when working with header-only template code that wasn't separated into the usual "*.hpp/*.inl" pair. In that scenario, the size of the function implementations overpowered this small but important information. My question is simple and stems from the fact that I've never seen anyone else actively do this in their C++ code. Assuming that I don't have a "Class View" capable IDE, are there any obvious drawbacks to using this level of verbosity? Any other style recommendations are welcome!

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• Linking two models in a multi-model form

  - by Elliot

  Hey Guys, I have a nested multimodel form right now, using Users and Profiles. Users has_one profile, and Profile belongs_to Users. When the form is submitted, a new user is created, and a new profile is created, but they are not linked (this is the first obvious issue). The user's model has a profile_id row, and the profile's model has a user_id row. Here is the code for the form: <%= form_for(@user, :url => teams_path) do |f| %> <p><%= f.label :email %><br /> <%= f.text_field :email %></p> <p><%= f.label :password %><br /> <%= f.password_field :password %></p> <p><%= f.label :password_confirmation %><br /> <%= f.password_field :password_confirmation %></p> <%= f.hidden_field :role_id, :value => @role.id %></p> <%= f.hidden_field :company_id, :value => current_user.company_id %></p> <%= fields_for @user.profile do |profile_fields| %> <div class="field"> <%= profile_fields.label :first_name %><br /> <%= profile_fields.text_field :first_name %> </div> <div class="field"> <%= profile_fields.label :last_name %><br /> <%= profile_fields.text_field :last_name %> </div> <% end %> <p><%= f.submit "Sign up" %></p> <% end %> A second issue, is even though the username, and password are successfully created through the form for the user model, the hidden fields (role_id & company_id - which are also links to other models) are not created (even though they are part of the model) - the values are successfully shown in the HTML for those fields however. Any help would be great!

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• async_write/async_read problems while trying to implement question-answer logic

  - by Max

  Good day. I'm trying to implement a question - answer logic using boost::asio. On the Client I have: void Send_Message() { .... boost::asio::async_write(server_socket, boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Client::Handle_Write_Message, this, boost::asio::placeholders::error)); .... } void Handle_Write_Message(const boost::system::error_code& error) { .... std::cout << "Message was sent.\n"; .... boost::asio::async_read(server_socket_,boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Client::Handle_Read_Message, this, boost::asio::placeholders::error)); .... } void Handle_Read_Message(const boost::system::error_code& error) { .... std::cout << "I have a new message.\n"; .... } And on the Server i have the "same - logic" code: void Read_Message() { .... boost::asio::async_read(client_socket, boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Server::Handle_Read_Message, this, boost::asio::placeholders::error)); .... } void Handle_Read_Message(const boost::system::error_code& error) { .... std::cout << "I have a new message.\n"; .... boost::asio::async_write(client_socket_,boost::asio::buffer(&Message, sizeof(Message)), boost::bind(&Server::Handle_Write_Message, this, boost::asio::placeholders::error)); .... } void Handle_Write_Message(const boost::system::error_code& error) { .... std::cout << "Message was sent back.\n"; .... } Message it's just a structure. And the output on the Client is: Message was sent. Output on the Server is: I have a new message. And that's all. After this both programs are still working but nothing happens. I tried to implement code like: if (!error) { .... } else { // close sockets and etc. } But there are no errors in reading or writing. Both programs are just running normally, but doesn't interact with each other. This code is quite obvious but i can't understand why it's not working. Thanks in advance for any advice.

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• Optimize slow ranking query

  - by Juan Pablo Califano

  I need to optimize a query for a ranking that is taking forever (the query itself works, but I know it's awful and I've just tried it with a good number of records and it gives a timeout). I'll briefly explain the model. I have 3 tables: player, team and player_team. I have players, that can belong to a team. Obvious as it sounds, players are stored in the player table and teams in team. In my app, each player can switch teams at any time, and a log has to be mantained. However, a player is considered to belong to only one team at a given time. The current team of a player is the last one he's joined. The structure of player and team is not relevant, I think. I have an id column PK in each. In player_team I have: id (PK) player_id (FK -> player.id) team_id (FK -> team.id) Now, each team is assigned a point for each player that has joined. So, now, I want to get a ranking of the first N teams with the biggest number of players. My first idea was to get first the current players from player_team (that is one record top for each player; this record must be the player's current team). I failed to find a simple way to do it (tried GROUP BY player_team.player_id HAVING player_team.id = MAX(player_team.id), but that didn't cut it. I tried a number of querys that didn't work, but managed to get this working. SELECT COUNT(*) AS total, pt.team_id, p.facebook_uid AS owner_uid, t.color FROM player_team pt JOIN player p ON (p.id = pt.player_id) JOIN team t ON (t.id = pt.team_id) WHERE pt.id IN ( SELECT max(J.id) FROM player_team J GROUP BY J.player_id ) GROUP BY pt.team_id ORDER BY total DESC LIMIT 50 As I said, it works but looks very bad and performs worse, so I'm sure there must be a better way to go. Anyone has any ideas for optimizing this? I'm using mysql, by the way. Thanks in advance Adding the explain. (Sorry, not sure how to format it properly) id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY t ALL PRIMARY NULL NULL NULL 5000 Using temporary; Using filesort 1 PRIMARY pt ref FKplayer_pt77082,FKplayer_pt265938,new_index FKplayer_pt77082 4 t.id 30 Using where 1 PRIMARY p eq_ref PRIMARY PRIMARY 4 pt.player_id 1 2 DEPENDENT SUBQUERY J index NULL new_index 8 NULL 150000 Using index

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• jQuery ajax multiline "script" response

  - by Rendrik

  I'm designing a template creation tool, which uses a jQuery Ajax request that posts parameters to a PHP file. The PHP does the actual generation of the template's HTML. // Send for processing. Expect JS back to execute. function generate() { $.ajax({ type: "POST", url: "generate.php", data: $('#genform :input').serialize(), dataType: "script", beforeSend: function() { $("#loading").html("<img src='images/loadbar.gif' />"); $("#loading") .dialog({ height: 80, width: 256, autoOpen: true, modal: true }); }, success: function(data) { $("#loading").dialog('close'); } }); } My trouble is that I have the ajax dataType: set to "script". Using this, the PHP file generates some jQuery dialogs for any errors which works nicely. However, after I generate the HTML, i'm having trouble passing it back. So I have probably 100 lines of generated HTML and javascript which i'd like to work with. In the PHP file, i've tried: echo('$("#result").html("'.$html.'");'); This does actually work if there are NO line breaks in $html. As soon as there are any line breaks, the Chrome debugger reports "gen.html:1 Uncaught SyntaxError: Unexpected token ILLEGAL". It's obvious that it's trying to eval the returned response headers, but is stopping at any line break. So, to be clear, when I pass $html back, if the contents are this: $html = "<div>hi there</div>"; It works fine (all of my error message dialogs are one line). But if it's: $html = "<div> hi there </div>"; It blows up. I'm really not sure how to get around this, or if there's a better way to go about it. It's important to me to keep the formatting so people can copy the HTML template. I may just break down and display the template file on the PHP page if I can't solve this, but I was really hoping to keep everything within the confines of the HTML page.

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• Safely escaping and reading back a file path in ruby

  - by user336851

  I need to save a few informations about some files. Nothing too fancy so I thought I would go with a simple one line per item text file. Something like this : # write io.print "%i %s %s\n" % [File.mtime(fname), fname, Digest::SHA1.file(fname).hexdigest] # read io.each do |line| mtime, name, hash = line.scanf "%i %s %s" end Of course this doesn't work because a file name can contain spaces (breaking scanf) and line breaks (breaking IO#each). The line break problem can be avoided by dropping the use of each and going with a bunch of gets(' ') while not io.eof? mtime = Time.at(io.gets(" ").to_i) name = io.gets " " hash = io.gets "\n" end Dealing with spaces in the names is another matter. Now we need to do some escaping. note : I like space as a record delimiter but I'd have no issue changing it for one easier to use. In the case of filenames though, the only one that could help is ascii nul "\0" but a nul delimited file isn't really a text file anymore... I initially had a wall of text detailing the iterations of my struggle to make a correct escaping function and its reciprocal but it was just boring and not really useful. I'll just give you the final result: def write_name(io, val) io << val.gsub(/([\\ ])/, "\\\\\\1") # yes that' 6 backslashes ! end def read_name(io) name, continued = "", true while continued continued = false name += io.gets(' ').gsub(/\\(.)/) do |c| if c=="\\\\" "\\" elsif c=="\\ " continued=true " " else raise "unexpected backslash escape : %p (%s %i)" % [c, io.path, io.pos] end end end return name.chomp(' ') end I'm not happy at all with read_name. Way too long and akward, I feel it shouldn't be that hard. While trying to make this work I tried to come up with other ways : the bittorrent encoded / php serialize way : prefix the file name with the length of the name then just io.read(name_len.to_i). It works but it's a real pita to edit the file by hand. At this point we're halfway to a binary format. String#inspect : This one looks expressly made for that purpose ! Except it seems like the only way to get the value back is through eval. I hate the idea of eval-ing a string I didn't generate from trusted data. So. Opinions ? Isn't there some lib which can do all this ? Am I missing something obvious ? How would you do that ?

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• Are there any platforms where using structure copy on an fd_set (for select() or pselect()) causes p

  - by Jonathan Leffler

  The select() and pselect() system calls modify their arguments (the 'struct fd_set *' arguments), so the input value tells the system which file descriptors to check and the return values tell the programmer which file descriptors are currently usable. If you are going to call them repeatedly for the same set of file descriptors, you need to ensure that you have a fresh copy of the descriptors for each call. The obvious way to do that is to use a structure copy: struct fd_set ref_set_rd; struct fd_set ref_set_wr; struct fd_set ref_set_er; ... ...code to set the reference fd_set_xx values... ... while (!done) { struct fd_set act_set_rd = ref_set_rd; struct fd_set act_set_wr = ref_set_wr; struct fd_set act_set_er = ref_set_er; int bits_set = select(max_fd, &act_set_rd, &act_set_wr, &act_set_er, &timeout); if (bits_set > 0) { ...process the output values of act_set_xx... } } My question: Are there any platforms where it is not safe to do a structure copy of the struct fd_set values as shown? I'm concerned lest there be hidden memory allocation or anything unexpected like that. (There are macros/functions FD_SET(), FD_CLR(), FD_ZERO() and FD_ISSET() to mask the internals from the application.) I can see that MacOS X (Darwin) is safe; other BSD-based systems are likely to be safe, therefore. You can help by documenting other systems that you know are safe in your answers. (I do have minor concerns about how well the struct fd_set would work with more than 8192 open file descriptors - the default maximum number of open files is only 256, but the maximum number is 'unlimited'. Also, since the structures are 1 KB, the copying code is not dreadfully efficient, but then running through a list of file descriptors to recreate the input mask on each cycle is not necessarily efficient either. Maybe you can't do select() when you have that many file descriptors open, though that is when you are most likely to need the functionality.) There's a related SO question - asking about 'poll() vs select()' which addresses a different set of issues from this question.

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