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  • Insert A Line At The Beginning Of A File

    - by thebourneid
    I'm trying to insert/add a line 'COMMENT DUMMY' at the beginnig of a file as a first row if /PATTERN/ not found. I know how to do this with OPEN CLOSE function. Probably after reading the file it should look something like this: open F, ">", $fn or die "could not open file: $!"; ; print F "COMMENT DUMMY\n", @array; close F; But I have a need to implement this with the use of the Tie::File function and don't know how. use strict; use warnings; use Tie::File; my $fn = 'test.txt'; tie my @lines, 'Tie::File', $fn or die "could not tie file: $!"; untie @lines;

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  • Sqlalchemy layout with WSGI application

    - by TheDude
    I'm working on writing a small WSGI application using Bottle and SqlAlchemy and am confused on how the "layout" of my application should be in terms of SqlAlchemy. My confusion is with creating engines and sessions. My understanding is that I should only create one engine with the 'create_engine' method. Should I be creating an engine instance in the global namespace in some sort of singleton pattern and creating sessions based off of it? How have you done this in your projects? Any insight would be appreciated. The examples in the documentation dont seem to make this entirely clear (unless I'm missing something obvious). Any thoughts?

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  • Exception handling in Boost.Asio

    - by Alex B
    Boost.Asio documentation suggests the following exception handling pattern: boost::asio::io_service io_service; ... for (;;) { try { io_service.run(); break; // run() exited normally } catch (my_exception& e) { // Deal with exception as appropriate. } } The problem with it is that the context of exception is lost at the point when it's handled. For example, if I have multiple socket sessions going on, I don't know which one caused the exception to be thrown. What would be a better way to handle the exceptions from asynchronous handlers without wrapping them in try/catch blocks?

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  • Immutability of big objects

    - by Malax
    Hi StackOverflow! I have some big (more than 3 fields) Objects which can and should be immutable. Every time I run into that case i tend to create constructor abominations with long parameter lists. It doesn't feel right, is hard to use and readability suffers. It is even worse if the fields are some sort of collection type like lists. A simple addSibling(S s) would ease the object creation so much but renders the object mutable. What do you guys use in such cases? I'm on Scala and Java, but i think the problem is language agnostic as long as the language is object oriented. Solutions I can think of: "Constructor abominations with long parameter lists" The Builder Pattern Thanks for your input!

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  • GUI system architecture?

    - by topright
    I'm designing GUI (graphical user interface) system for a game engine (C++). Idea is to create a heirarchy of GUI controllers like Focusable, Hoverable, Dragable etc. Every GUI component can attach multiple controllers, they modify component's behaviour. I think it gives flexible system and protects from code duplication. Different instances of the same GUI class can have different complex behaviours (may be, even change it dynamically), so this approach looks practical. The other choice is to add focused, hovered, dragged etc. flags in the base GUI component class. It looks like overhead and not that flexible. Another solution is to use Decorator pattern and wrap objects with FocusDecorator, HoverDecorator etc. Maintaining such system looks a bit harder. Question: What are pitfalls in my solution? May be you have seen a better approaches in GUI systems? What are the best ways of implementing such flexible complex system?

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  • How to tell when my batch of EAP calls are completed?

    - by codemonkie
    This is following my question: http://stackoverflow.com/questions/2607038/c-how-to-consume-web-service-adheres-to-the-event-based-asynchronous-pattern My program is calling the DoStuffAsync() x many times in a batch, hence the callback will get invoked the same number of times upon OnComplete(). Is there a way to find out when my batch is finished such that I can generate a report on the success/failed results? All I can think of is to have a static count variable for x and deduct 1 every time OnComplete() is called, but its kind of silly and error prone I'm afraid. TIA.

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  • Pass a captured named regular expression to URL dictionary in generic view

    - by Trent Jurewicz
    I am working with a generic view in Django. I want to capture a named group parameter in the URL and pass the value to the URL pattern dictionary. For example, in the URLConf below, I want to capture the parent_slug value in the URL and pass it to the queryset dictionary value like so: urlpatterns = patterns('django.views.generic.list_detail', (r'^(?P<parent_slugs>[-\w])$', 'object_list', {'queryset':Promotion.objects.filter(category=parent_slug)}, 'promo_promotion_list'), ) Is this possible to do in one URLConf entry, or would it be wiser if I create a custom view to capture the value and pass the queryset directly to the generic view from my overridden view?

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  • Random directions, with no repeat.. (Bad Description)

    - by Neurofluxation
    Hey there, So I'm knocking together a random pattern generation thing. My code so far: int permutes = 100; int y = 31; int x = 63; while (permutes > 0) { int rndTurn = random(1, 4); if (rndTurn == 1) { y = y - 1; } //go up if (rndTurn == 2) { y = y + 1; } //go down if (rndTurn == 3) { x = x - 1; } //go right if (rndTurn == 4) { x = x + 1; } //go left setP(x, y, 1); delay(250); } My question is, how would I go about getting the code to not go back on itself? e.g. The code says "Go Left" but the next loop through it says "Go Right", how can I stop this? NOTE: setP turns a specific pixel on. Cheers peoples!

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  • How to access File over the Network

    - by Polo
    Hi! I am having a hard time on this one, I have a folder over the network with public access (no credential restriction). I am trying to do a File.Exist or Directory.Exist and I keep on having a exception. Can someone tell me the good way to do IO over the network. EDIT 1 FOR DETAILS: if i do execture = \agoodip\Public\test.txt I get the file etc etc In my code it look like a basic Directory.Exist(@"\\agoodip\Public") or File.exist(@"\\agoodip\Public\test.txt") The exception I get is Path not found. EDIT 2 : I am using Silverlight 3, Is there any security pattern to be aware of to lookup file on the network? Thanks!

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  • Django - Tips to avoid repeating code in views

    - by D Roddis
    I'm moving from a PHP background into Django development via python, mostly for the sake of tackling a MVC (or MVT) that I feel makes the most sense, although in this pattern I've started to notice a lot of repeated code in my views. For example, when logged in I have information regarding the user that I would like to appear on every page, although when using render_to_response and in every view this is required I have to grab the information and pass it to the render_to_response function. I'm wondering what would be the most efficient way to cut down on the duplicate code which would in essence be required in all views in a particular app. Thanks in advance.

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  • Is there any benefit to declaring a private property with a getter and setter?

    - by AmoebaMan17
    I am reviewing another developer's code and he has written a lot of code for class level variables that is similar to the following: /// <summary> /// how often to check for messages /// </summary> private int CheckForMessagesMilliSeconds { get; set; } /// <summary> /// application path /// </summary> private string AppPath { get; set; } Doesn't coding this way add unnecessary overhead since the variable is private? Am I not considering a situation where this pattern of coding is required for private variables?

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  • MVVM View reference to ViewModel

    - by BrettRobi
    I'm using MVVM in a WPF app. I'm very new to both. Let me state that I am not a purest in the MVVM pattern, I am trying to use as many best practices as I can but am trying to make what I think are reasonable compromises to make it work in our environment. For example, I am not trying to achieve 0% code in my View codebehind. I have a couple of questions about best practices. 1) I understand I don't want my VM to know about the attached View, but is it reasonable for the View to have a reference to its VM? 2) If a control in a View opens another View (such as a dialog) should I handle this in the View? It seems wrong to handle it in the VM since then the VM has some knowledge of a specific View.

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  • What can I use the Google App Engine for?

    - by Sergio Boombastic
    This question possibly doesn't belong here. We'll see how the answers pan out, if this doesn't belong here please move it to where it belongs. I'm following the getting started guide for Google App Engine, and I'm seeing what it can and can't do. Basically, I'm seeing it's very similar to an MVC pattern. You create your model, then create a View that uses that Model to display information. Not only that, but it uses a controller of some kind in this fashion: application = webapp.WSGIApplication( [('/', MainPage)], debug=True) My question is, why would you use this Google App Engine if it's the same as using a number of other MVC frameworks? Is the only benefit you gain the load balancing being handled by Google automagically? What is a good example of something you would need the App Engine for? I'm trying to learn, so thanks for the discussion.

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  • what happens to running/blocked runnables when executorservice is shutdown()

    - by prmatta
    I posted a question about a thread pattern today, and almost everyone suggested that I look into the ExecutorService. While I was looking into the ExecutorService, I think I am missing something. What happens if the service has a running or blocked threads, and someone calls ExecutorService.shutdown(). What happens to threads that are running or blocked? Does the ExecutorService wait for those threads to complete before it terminates? The reason I ask this is because a long time ago when I used to dabble in Java, they deprecated Thread.stop(), and I remember the right way of stopping a thread was to use sempahores and extend Thread when necessary: public void run () { while (!this.exit) { try { block(); //do something } catch (InterruptedException ie) { } } } public void stop () { this.exit = true; if (this.thread != null) { this.thread.interrupt(); this.thread = null; } } How does ExecutorService handle running threads?

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  • Data access strategy for a site like SO - sorted SQL queries and simultaneous updates that affect th

    - by Kaleb Brasee
    I'm working on a Grails web app that would be similar in access patterns to StackOverflow or MyLifeIsAverage - users can vote on entries, and their votes are used to sort a list of entries based on the number of votes. Votes can be placed while the sorted select queries are being performed. Since the selects would lock a large portion of the table, it seems that normal transaction locking would cause updates to take forever (given enough traffic). Has anyone worked on an app with a data access pattern such as this, and if so, did you find a way to allow these updates and selects to happen more or less concurrently? Does anyone know how sites like SO approach this? My thought was to make the sorted selects dirty reads, since it is acceptable if they're not completely up to date all of the time. This is my only idea for possibly improving performance of these selects and updates, but I thought someone might know a better way.

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  • Looking for a good explanation of the table generation macro idiom

    - by detly
    I want to make this clear up front : I know how this trick works, what I want is a link to a clear explanation to share with others. One of the answers to a C macro question talks about the "X macro" or "not yet defined macro" idiom. This involves defining something like: #define MAGIC_LIST \ X(name_1, default_1) \ X(name_2, default_2) \ ... Then to create, say, an array of values with named indices you do: typedef enum { #define X(name, val) name, MAGIC_LIST #undef X } NamedDefaults; You can repeat the procedure with a different #define for X() to create an array of values, and maybe debugging strings, etc. I'd like a link to a clear explanation of how this works, pitched at someone who is passably familiar with C. I have no idea what everyone usually calls this pattern, though, so my attempts to search the web for it have failed thus far. (If there is such an explanation on SO, that'd be fine...)

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  • Can you use data binding with the Content property of a WPF Frame?

    - by dthrasher
    I can use data binding to set the initial Content of a WPF Frame, but subsequent changes to the the bound property (implemented using INotifyPropertyChange) do not seem to change the content. Also, does anyone know if binding directly to the Content property in this way will cause the bound item to appear in the Frame or NavigationWindow's journal? Some context: I realize that I should probably be using the NavigationService to interact with the Frame, but I'm attempting to follow the MVVM pattern. It seems like it would be much simpler to databind to the Content property...

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  • VB.net: Custom ' TODO: List on an Interface

    - by Shiftbit
    How do I add my own todo and comments list to appear on Interfaces? I want it to pop up like IDisposable does: Public Class Foo : Implements IDisposable Private disposedValue As Boolean = False ' To detect redundant calls ' IDisposable Protected Overridable Sub Dispose(ByVal disposing As Boolean) If Not Me.disposedValue Then If disposing Then ' TODO: free other state (managed objects). End If ' TODO: free your own state (unmanaged objects). ' TODO: set large fields to null. End If Me.disposedValue = True End Sub #Region " IDisposable Support " ' This code added by Visual Basic to correctly implement the disposable pattern. Public Sub Dispose() Implements IDisposable.Dispose ' Do not change this code. Put cleanup code in Dispose(ByVal disposing As Boolean) above. Dispose(True) GC.SuppressFinalize(Me) End Sub #End Region End Class Whenever I enter my own comments and todo list they are never autogenerated like IDisposable Interface does. I would like my own Interfaces to preserve the comments so that I can share my Interfaces with in source documentation.

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  • Only error showing is null, rss feed reader not working

    - by Callum
    I have been following a tutorial which is showing me how to create an rssfeed reader, I come to the end of the tutorial; and the feed is not displaying in the listView. So I am looking for errors in logCat, but the only one I can find is one just saying 'null', which is not helpful at all. Can anyone spot a potential problem with the code I have written? Thanks. DirectRSS(main class): package com.example.rssapplication; import java.util.List; import android.app.ListActivity; import android.content.pm.ActivityInfo; import android.os.Bundle; import android.util.Log; import android.widget.ArrayAdapter; import android.widget.ListView; public class DirectRSS extends ListActivity{ @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.directrss); //Set to portrait, so that every time the view changes; it does not run the DB query again... setRequestedOrientation (ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); try{ RssReader1 rssReader = new RssReader1("http://www.skysports.com/rss/0,20514,11661,00.xml"); ListView list = (ListView)findViewById(R.id.list); ArrayAdapter<RssItem1> adapter = new ArrayAdapter<RssItem1>(this, android.R.layout.simple_list_item_1); list.setAdapter(adapter); list.setOnItemClickListener(new ListListener1(rssReader.getItems(),this)); }catch(Exception e) { String err = (e.getMessage()==null)?"SD Card failed": e.getMessage(); Log.e("sdcard-err2:",err + " " + e.getMessage()); // Log.e("Error", e.getMessage()); Log.e("LOGCAT", "" + e.getMessage()); } } } ListListener1: package com.example.rssapplication; import java.util.List; import android.app.Activity; import android.content.Intent; import android.net.Uri; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; public class ListListener1 implements OnItemClickListener{ List<RssItem1> listItems; Activity activity; public ListListener1(List<RssItem1> listItems, Activity activity) { this.listItems = listItems; this.activity = activity; } @Override public void onItemClick(AdapterView<?> parent, View view, int pos, long id) { // TODO Auto-generated method stub Intent i = new Intent(Intent.ACTION_VIEW); i.setData(Uri.parse(listItems.get(pos).getLink())); activity.startActivity(i); } } RssItem1: package com.example.rssapplication; public class RssItem1 { private String title; private String link; public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getLink() { return link; } public void setLink(String link) { this.link = link; } } RssParseHandler1: package com.example.rssapplication; import java.util.ArrayList; import java.util.List; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; public class RssParseHandler1 extends DefaultHandler{ private List<RssItem1> rssItems; private RssItem1 currentItem; private boolean parsingTitle; private boolean parsingLink; public RssParseHandler1(){ rssItems = new ArrayList<RssItem1>(); } public List<RssItem1> getItems(){ return rssItems; } @Override public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if("item".equals(qName)){ currentItem = new RssItem1(); } else if("title".equals(qName)){ parsingTitle = true; } else if("link".equals(qName)){ parsingLink = true; } // TODO Auto-generated method stub super.startElement(uri, localName, qName, attributes); } @Override public void endElement(String uri, String localName, String qName) throws SAXException { if("item".equals(qName)){ rssItems.add(currentItem); currentItem = null; } else if("title".equals(qName)){ parsingTitle = false; } else if("link".equals(qName)){ parsingLink = false; } // TODO Auto-generated method stub super.endElement(uri, localName, qName); } @Override public void characters(char[] ch, int start, int length) throws SAXException { if(parsingTitle) { if(currentItem!=null) { currentItem.setTitle(new String(ch,start,length)); } } else if(parsingLink) { if(currentItem!=null) { currentItem.setLink(new String(ch,start,length)); parsingLink = false; } } // TODO Auto-generated method stub super.characters(ch, start, length); } } RssReader1: package com.example.rssapplication; import java.util.List; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; public class RssReader1 { private String rssUrl; public RssReader1(String rssUrl) { this.rssUrl = rssUrl; } public List<RssItem1> getItems() throws Exception { SAXParserFactory factory = SAXParserFactory.newInstance(); SAXParser saxParser = factory.newSAXParser(); RssParseHandler1 handler = new RssParseHandler1(); saxParser.parse(rssUrl, handler); return handler.getItems(); } } Here is the logCat also: 08-25 11:13:20.803: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.803: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.803: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.813: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.813: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.813: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.813: W/ApplicationPackageManager(26291): getCSCPackageItemText() 08-25 11:13:20.843: D/AbsListView(26291): Get MotionRecognitionManager 08-25 11:13:20.843: E/sdcard-err2:(26291): SD Card failed null 08-25 11:13:20.843: E/LOGCAT(26291): null 08-25 11:13:20.843: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 4 08-25 11:13:20.843: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.873: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 0 08-25 11:13:20.883: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.903: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.933: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.963: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:20.973: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:21.323: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 4 08-25 11:13:21.323: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:21.323: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 4 08-25 11:13:21.323: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:21.323: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 4 08-25 11:13:21.323: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:21.323: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 4 08-25 11:13:21.323: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:21.323: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 4 08-25 11:13:21.323: D/AbsListView(26291): unregisterIRListener() is called 08-25 11:13:21.333: D/AbsListView(26291): onVisibilityChanged() is called, visibility : 4 08-25 11:13:21.333: D/AbsListView(26291): unregisterIRListener() is called

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  • how to start animation using MVVM?

    - by Kishore Kumar
    I am converting my exising Application using WPF using MVVM pattern. I have different storyboards in my view . eg. 1. showing splashscreen while loading the app 2. while clicking Menu Toggle button/Radio Button to show the slide in and Slide out animation effect 3. And different mouseover effect for different elements available in the View. How will i call the storyboard using MVVM and which is the best method?. To show the mouse over effect do we really have to use MVVM or code behind?

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  • IIS7 301 Redirect from a List of URLs

    - by corymathews
    Recent changes are forcing me to add a bunch of 301 redirects. Seems that IIS7 is my best bet as compared to redirects within the files. I have found how to add them 1 by 1 but this requires the page/folder to exist (which most don't anymore(and creating them seems to defeat the point of the redirect)) and does not work on dynamic urls. I also cannot go to every page and add the redirects at the page level because some older pages are in php which is no longer supported on the new server. There is also no obvious pattern to the changes so each one must be made on its own. samples of the redirects page.htm - /page/ /folder/folder/ - /folder/folder.cfm /folder/folder/ - /folder/ /page.php?id=1 - page.htm

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  • Rails: common approach for handling exceptions in restful actions on objects that have been destroye

    - by Greg
    It is very common in Rails for an objects_controller controller to have RESTful edit and destroy actions like so: def edit @object = Object.find(params[:id]) end def destroy @object = Object.find(params[:id]) @object.destroy redirect_to :back end With an associated view that provides edit and destroy links like so: <%= link_to "Edit the Object", edit_object_path(object) %> <%= link_to "Delete", object, :confirm => 'Are you sure?', :method => :delete %> And it is easy to blow this up. If I open two browser windows, A and B, destroy an object with the "Delete" link in browser A and then press the "Edit" link in browser B, the find() in the edit action throws an exception. Obviously there are several ways to deal with this in the edit action: catch the exception and recover gracefully use @object = find(:first, "conditions... etc. and test the @object before going further But seeing as this is such a common pattern, I would love to know how other folks deal with this situation.

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  • How to check connection leak using regular expression ?

    - by gauravkarnatak
    I have to check connection leak in my application i.e. open connections which have not been closed. After searching, after I found out that a thousands times connections have been opened but I can't manually go to each and every code fragment and check for connection close thing. I think, it could be possible using a regular expression but the fact is, I am not that well versed with regex that I could write one. Please suggest a regular expression for checking in a no of java files that a opened connection has been closed or not. My code pattern is something like this. try { /* Some code goes here */ con = EJBUtil.getConnection(JNDI_NAME); /* Some code goes here */ } finally { /* Some code goes here */ DBUtil.close(con); or closeConnection.close(con); /* Some code goes here */ }

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  • Is it a bad idea to have a login dialog inside an iframe?

    - by AyKarsi
    We're creating a website where we will be giving out code snippets to our users which they can place on their own websites. These snippets contain a link a javascript include. When clicking the link, an iframe containing the login dialog to our site opens. The user then authenticates inside the iframe, does his work and when he leaves the iframe his session is closed. We've got it working allready and it's very slick. Our main concern though is phishing. The user has absolutely now way of veryifying where the login page is really coming from. On the other hand, phising attacks are also succesfull even if the user can see the fake-url in the address bar. Would you enter your (OpenId) credentials in an iframe? Does anyone know a pattern with which we could minimise the chances of a phishing attack?

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  • emacs: inverse search

    - by Data
    Is there a way to do a inverse search? I have very big log file where a particular pattern fills up for few dozen pages 20100414 alpha beta 20100414 alpha beta <few dozen pages> 20100414 alpha beta 20100414 gamma delta 20100414 gamma delta <few dozen pages> 20100414 gamma delta Problem is, I don't know what text would be after "alpha beta". It could be "gamma delta" or something else. So I would like to skip all the lines that contain "alpha beta".

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