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  • How do I remove a control if not a specific type?

    - by joek1975
    I have a control that I need to restrict the types of child controls that it can contain during design time (dragging a new control onto an existing control on the form designer). I tried to do this by overriding the OnControlAdded event: Protected Overrides Sub OnControlAdded(ByVal e As System.Windows.Forms.ControlEventArgs) MyBase.OnControlAdded(e) If e.Control.GetType() IsNot GetType(ExpandablePanel) Then MsgBox("You can only add the ExpandablePanel control to the TaskPane.", MsgBoxStyle.Exclamation Or MsgBoxStyle.OkOnly, "TaskPane") Controls.Remove(e.Control) End If End Sub This seems to work, however I get an error message from Visual Studio immediately after the control is removed: 'child' is not a child control of this parent. What does this mean? How can I accomplish this without errors occurring?

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  • replace asp.net Response.Output with my own content

    - by WebDude
    I am trying to intercept a asp.net web request and based on a lookup replace the page thats going to be rendered to the client. example: is a request for "/about-us" comes to my web server, i will first see if i have a version of this in the database, otherwise i will revert to flat files. The version i will retrieve from the database will be a .aspx page that has to be rendered and containt web controls and inline serverside script. What is the best way to go about this? I have tried overriding the CreateHtmlTextWriter method but this seems too late in the process as the TextWriter passed to this method is already instantiated. I have also tried to Implement my own PageHandlerFactory but this seems to create an instance of Page of which i cannot seem to override its internal setting of the Response.Output stream. Amd i barking up the wrong tree here? what is the best approach to take here?

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  • Control the MultipleOutputFormat files sub-path

    - by iCode
    I need to control the sub-path of the different different files being managed by MultipleOutputFormat based on the reducer key. I basically want to set the sub path of the file based on the key given to the reducer. I can changed the file name by overwrting the generateFileNameForKeyValue method of MultipleOutputFormatbut how can I also change the sub-path of these files? I mean with just overriding the generateFileNameForKeyValue, I get mySetJobConfigOutputPath/fileNameBasedKey1.dat /fileNameBasedKey2.dat /fileNameBasedKey3.dat ... but I want to make it to be organize files like below mySetJobConfigOutputPath/path0ConfiguredInsideReducerBasedOnKey/fileNameBasedKey1.dat /path1ConfiguredInsideReducerBasedOnKey/fileNameBasedKey2.dat /fileNameBasedKey3.dat /path2ConfiguredInsideReducerBasedOnKey/fileNameBasedKey8.dat as seen, the sub-path and the file name are both figured out by the key inside the reducer. I know how to configure the file name but was wondering if I can configure the sub-path of the each file under the mySetJobConfigOutputPath folder?

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  • If a NSView uses autolayout, do all of its subviews also need to use autolayout for positioning?

    - by boyfarrell
    I have a view in a window, the position and size of the view are calculated with autolayout. The view has a subview, a draggable NSView subclass. It is really easy to make a NSView "draggable" by overriding -mouseDown: and -mouseDragged: and changing the frame of the view directly. The view hierarchy is as follows, What is the best way of making the subview draggable in this case? For example, Is it possible for the subview to not use autolayout, so that it can be positioned by changing the frame directly? i.e. the window positions the main view, but then autolayout does not layout the subview inside the main view. Or to all views in the hierarchy need to use autolayout. When I have used autolayout before, I have used it to make "fixed" layout that respond to resizing. But dragging a view with a mouse does't seems like a natural use case for autolayout.

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  • Blackberry Developement

    - by varun
    Hi, I am new to Blackberry Development.This is my first Question for you people. I am creating a search box for my project. But it looks like blackberry doesn't have an internal api for creating single line Edit field. I have created a Custom Field by extending BasciEditField overriding methods like layout, paint. In paint i am drawing a rectangle with getpreferred width and height. But the cursor is coming at default position (top-left) in Edit Field. Can any body tell me how i can draw it where my text is(i.e in middle of Edit Field by calling drwaText()). Thanks,

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  • Objective C - Custom Getter with inheritance

    - by anhdat
    Recently I have worked with Core Data. When I want to set a default value for some fields, I came up with this problem: So I made a simple represent: We have 2 class Parent and Child, in which Child inherit from Parent. // Parent.h @interface Parent : NSObject @property (strong, nonatomic) NSString *lastName; // Child.h @interface Child : Parent In Parent class, I made a custom getter to set a default value when nothing is set: // Parent.h - (NSString *)lastName { if (_lastName) { return _lastName; } else { return @"Parent Default Name"; } } But I cannot make a custom default value for the field "name" which Child inherits from its Parent. // Child.h @implementation Child - (NSString *)lastname { if (super.lastName) { return super.lastName; } else { return @"Child Default Name"; } } Apparently, this method is never called. So my question here is: How can I set a custom getter for the field the Child class inherits from Parent without define an overriding property?

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  • How to use AOP to intercept a method call in super on an argument?

    - by hleinone
    I'm extending a class and overriding a method. All I want to do is to call super, but with a modified argument that gets intercepted upon one of its methods is called. An example makes it more clear: // Foo is an interface and also this method is part of an interface @Override public void foo(Foo foo) { // I want to intercept the call to foo.bar() in super super.foo(foo); } I'd rather use a tool that doesn't require a compiler of its own. What would be the optimal one?

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  • Do not want Form to display over other application windows

    - by Cat
    I am displaying a Form from one process by passing the Show method a window handle from another process. I only want this new Form to display above the passed Form, like a MessageBox. However, this newly launched Form appears above other application windows, despite: Setting Process.WindowStyle.Hidden to the Form-displaying process Overriding the ShowWithoutActivation and CreateParams properties of the Form. Making sure Form.TopMost is not true I have checked that the window handle is valid from the second process. Focus is not stolen, however. Process A: Pass (Form) window handle to a new Process B via the command line Process B: Display a new Form using Form.Show(anotherProcessWindowHandle)

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  • Android: Scrollable (bitmap) screen

    - by somin
    I am currently implementing a view in Android that involves using a larger than the screen size bitmap as a background and then having drawables drawn ontop of this. This is so as to simulate a "map" that can be scrolled horizontally aswell as vertically. Which is done by using a canvas and then drawing to this the full "map" bitmap, then putting the other images on top as an overlay and then drawing only the viewable bit of this to screen. Overriding the touch events to redraw the screen on a scroll/fling. I'm sure this probably has a huge ammount of overhead (by creating a canvas of the full image whilst using(drawing) only a fifth of it) and could be done in a different way as to the explained, but I was just wondering what people would do in this situation, and perhaps examples? If you need more info just let me know, Thanks, Simon

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  • How to $.extend 2 objects by adding numerical values together from keys with the same name?

    - by muudless
    I currently have 2 obj and using the jquery extend function, however it's overriding value from keys with the same name. How can I add the values together instead? obj1 = {"orange":2,"apple":1, "grape":1} obj2 = {"orange":5,"apple":1, "banana":1} mergedObj = $.extend({}, obj1, obj2); var printObj = typeof JSON != "undefined" ? JSON.stringify : function(obj) { var arr = []; $.each(obj, function(key, val) { var next = key + ": "; next += $.isPlainObject(val) ? printObj(val) : val; arr.push( next ); }); return "{ " + arr.join(", ") + " }"; }; console.log('all together: '+printObj(mergedObj) ); And I get obj1 = {"orange":5,"apple":1, "grape":1, "banana":1} What I need is obj1 = {"orange":7,"apple":2, "grape":1, "banana":1}

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  • Android TextWatcher for more than one EditText

    - by Creative MITian
    I want to implement the TextWatcher interface for more than one EditText fields. Currently I am using : text1.addTextChangedListener(this); text2.addTextChangedListener(this); then overriding the methods in my Activity: public void afterTextChanged(Editable s) {} public void beforeTextChanged(CharSequence s, int start, int count, int after) {} public void onTextChanged(CharSequence s, int start, int before, int count) { // do some operation on text of text1 field // do some operation on text of text2 field } However this is working fine but I'm looking for other ways so that I can explicitly identify that in which EditText field the SoftKeyboard is currently focused.

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  • Deleting files associated with model - django

    - by alexBrand
    I have the following code in one of my models class PostImage(models.Model): post = models.ForeignKey(Post, related_name="images") # @@@@ figure out a way to have image folders per user... image = models.ImageField(upload_to='images') image_infowindow = models.ImageField(upload_to='images') image_thumb = models.ImageField(upload_to='images') image_web = models.ImageField(upload_to='images') description = models.CharField(max_length=100) order = models.IntegerField(null=True) IMAGE_SIZES = { 'image_infowindow':(70,70), 'image_thumb':(100,100), 'image_web':(640,480), } def delete(self, *args, **kwargs): # delete files.. self.image.delete(save=False) self.image_thumb.delete(save=False) self.image_web.delete(save=False) self.image_infowindow.delete(save=False) super(PostImage, self).delete(*args, **kwargs) I am trying to delete the files when the delete() method is called on PostImage. However, the files are not being removed. As you can see, I am overriding the delete() method, and deleting each ImageField. For some reason however, the files are not being removed.

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  • Button top increase with multiple lines

    - by NeTeInStEiN
    Some very very strange behaviour was appearing in my Android application. I was extending Button to replace the standard. In my own button I set: - TextAppearence (text 16px, bold..) - BackgroundDrawable (to an selector that replaced the standard button, that used images of 60px) - Gravity: LEFT|CENTER_VERTICAL. Whenever the text was enough to make the button have 2 text lines, if it had the property Gravity.CENTER_VERTICAL, a top padding would appear! This kept me overflowing and googling for weeks... (set paddingTop, singleLine, and other simple solutions didn't work of course!) Finally got the solution!!! @Override protected boolean setFrame(int l, int t, int r, int b) { int fixedTopSize = 5; return super.setFrame(l,fixedTopSize, r, b-t); } By overriding this method on the extended Button finally i got it to work without the irritating top padding... still i don't understand why this happens. Any ideia?

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  • How to make my JavaScript code unusable by anyone else? [closed]

    - by egasimus
    Heh, that's something that many plugin authors do without needing help, isn't it? :) Here's the rub -- I'm coding a jQuery plugin which I have the intent to sell. I want to provide a live demo of it; of course, I don't want anyone just using the demo code. I know it's dumb, and it certainly doesn't bring any good karma, but what are some naughty things I can do in the demo script that would make life reasonably difficult for anyone trying to use it? Setting undefined = true comes to mind, as well as overriding jQuery methods. Any suggestions beyond that?

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  • Why can't I decrease the line-height of this text?

    - by daGUY
    http://jsfiddle.net/mJxn4/ This is very odd: I have a few lines of text wrapped in an <em> tag. No matter what I do, lowering the value for line-height below 17px has no effect. I can bump the line-height up to greater than 17px and it'll apply, but I can't get it lower than 17px. The CSS in question is: #others .item em { font-size: 13px; line-height: 17px; } Try adjusting the line height both higher and lower and run the updated fiddle after each change, and you'll see what I mean. Why would this be? No line-height is specified anywhere else in the CSS, so nothing is overriding it. That couldn't be the case anyway because I'm adjusting the line-height up and down within the same selector, so it doesn't make sense that a higher value would apply, but a lower value would get overridden.

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  • My Body Summary template for Orchard

    - by Bertrand Le Roy
    By default, when Orchard displays a content item such as a blog post in a list, it uses a very basic summary template that removes all markup and then extracts the first 200 characters. Removing the markup has the unfortunate effect of removing all styles and images, in particular the image I like to add to the beginning of my posts. Fortunately, overriding templates in Orchard is a piece of cake. Here is the Common.Body.Summary.cshtml file that I drop into the Views/Parts folder of pretty much all Orchard themes I build: @{ Orchard.ContentManagement.ContentItem contentItem = Model.ContentPart.ContentItem; var bodyHtml = Model.Html.ToString(); var more = bodyHtml.IndexOf("<!--more-->"); if (more != -1) { bodyHtml = bodyHtml.Substring(0, more); } else { var firstP = bodyHtml.IndexOf("<p>"); var firstSlashP = bodyHtml.IndexOf("</p>"); if (firstP >=0 && firstSlashP > firstP) { bodyHtml = bodyHtml.Substring(firstP, firstSlashP + 4 - firstP); } } var body = new HtmlString(bodyHtml); } <p>@body</p> <p>@Html.ItemDisplayLink(T("Read more...").ToString(), contentItem)</p> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This template does not remove any tags, but instead looks for an HTML comment delimiting the end of the post’s intro: <!--more--> This is the same convention that is being used in WordPress, and it’s easy to add from the source view in TinyMCE or Live Writer. If such a comment is not found, the template will extract the first paragraph (delimited by <p> and </p> tags) as the summary. And if it finds neither, it will use the whole post. The template also adds a localizable link to the full post.

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  • Smarter Ways to Unlock Your Unused Contingency Budgets

    - by Melissa Centurio Lopes
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Cash flow is becoming increasingly important in the current economy; senior executives are looking for smarter ways of unlocking unused funds for new or ongoing capital expenditure projects. With project contingency budgets on average equaling 10 percent of overall costs, are you confident that you can release this cash without risking existing investments or the health of your overall project portfolio? This is the central question posed in a new report from the EPPM board, Hedging Your Bets? Optimizing Investment Opportunities for Great Cash Flow. The board is Oracle’s international steering committee, which brings together senior figures from leading organizations to discuss the critical role of enterprise project portfolio management (EPPM). C-Level Visibility Will Unlock Funds In addition to exploring how unlocking your contingency funds enables you to augment your cash flow (without resorting to expensive borrowing), the report offers a number of suggestions on how this can be done in a risk-free way, including Building an effective governance framework that shows the demonstrable value of every project within the portfolio Undertaking contingency planning risk assessments that give you complete portfolio wide visibility into all risk factors Establishing executive ownership of the portfolio to promote a more realistic appreciation of the risk levels inherent in the portfolio Creating a chief risk officer role that can review consolidated contingencies and risks so they are not considered in isolation The overriding message behind the report—and the work carried out by the EPPM board—is the need for increased C-level visibility across the entire enterprise project portfolio to enable better business decisions. Read the complete report in English, Chinese, German, or French. Read more in the October Edition of the quarterly Information InDepth EPPM Newsletter

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  • How do I reconfigure my GLES frame buffer after a rotation?

    - by Panda Pajama
    I am implementing interface rotation for my GLES based game for iOS, written in Xamarin.iOS with OpenTK. I am detecting the rotation by overriding WillRotate, in my UIViewController, and I correctly re-setup all of my projection matrices. However, when drawing a sprite, the image looks a bit blurrier on the landscape version compared to the portrait version, as you can see in the following closeups magnified 10x. Portrait (before rotating) Landscape (after rotating) In both cases, I'm using the same texture with the same sampler, the same shader, and the same GL state. I just changed the order of the parameters in the projection matrix, so the resulting sizes should be exactly the same pixelwise. Since this could be thought of as a window resize, I suppose that the framebuffer has to be recreated to the new size. When working on desktop apps on Direct3D11 (SharpDX), I would have to call swapChain.ResizeBuffers() to do this. I have tried setting AutoResize = true in my iPhoneOSGameView, but then the framebuffer gets clipped as I rotate the interface, and then everything disappears when rotating the interface again. I'm not doing anything strange, my framebuffer initialization is pretty vanilla: int scaling = (int)UIScreen.MainScreen.Scale; DeviceWidth = (int)UIScreen.MainScreen.Bounds.Width * scaling; DeviceHeight = (int)UIScreen.MainScreen.Bounds.Height * scaling; Size = new System.Drawing.Size((int)(DeviceWidth), (int)(DeviceHeight)); Bounds = new System.Drawing.RectangleF(0, 0, DeviceWidth, DeviceHeight); Frame = new System.Drawing.RectangleF(0, 0, DeviceWidth, DeviceHeight); ContextRenderingApi = EAGLRenderingAPI.OpenGLES2; AutoResize = true; LayerRetainsBacking = true; LayerColorFormat = EAGLColorFormat.RGBA8; I get inconsistent results when changing Size, Bounds and Frame on my CreateFrameBuffer override, but since the documentation is so incomplete (it has nothing on Bounds and Frame), I have resorted to randomly changing stuff here and there without really knowing what is going on. There is a similar question which has no answers. However, I don't know if they're experiencing the same problem as I am. Is my supposition that recreating the framebuffer is necessary, correct? If so, does anybody know how to do it correctly in OpenTK for Xamarin.iOS?

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  • Adjusting the Score on Oracle Text search results

    - by Kyle Hatlestad
    When you sort the results of a search by Score using OracleTextSearch as the search engine in WebCenter Content, the results coming back are based on the relevancy on the document.  In theory, the more relevant the search term is to the document, the higher ranked Score it should receive.  But in practice, the relevancy score can seem somewhat of a mystery.  It's not entirely clear how it ranks the importance of some documents over others based on the search term.  And often times, once a word appears a certain number of times within a document, the Score simply maxes out at 100 and the top results can be difficult to discern from one another.  Take for example the search for 'vacation' on this set of documents: Out of 7 results, 6 of them have a Score of '100' which means they are basically ranked the same.  This doesn't make the sort by Score very meaningful.   Besides sorting by relevance, you can also tell Oracle Text to sort by occurrence.  In that case, it is a much more predictable result in how they would be ranked. And for many cases provide a more meaningful sorting of results then relevance. To change this takes a small component change to the SearchOperatorMap resource.  By default, the query used for full-text searching looks like: <td>(ORACLETEXTSEARCH)fullText</td> <td>DEFINESCORE((%V), RELEVANCE * .1)</td> <td>text</td> Overriding this resource and changing it to: <td>(ORACLETEXTSEARCH)fullText</td> <td>DEFINESCORE((%V), OCCURRENCE * .01)</td>  <td>text</td> will force it to now use occurrence (note the change in scale to .01 as well).  So running the same search and sort options as the example above, the results come out quite a bit differently: In this case, there is a clear understanding of how the items rank.   And generally, if the search term appears 3 times more in one document then another, it's got a better chance of being a document I'm interested in.  You may or may not feel the relevance ranking is better then the search term occurrence, but this provides the opportunity to try an alternate method that might work better for your results.  A pre-built component is available for download here. There is one caveat in using this method.  The occurrence ranking also maxes out at 100, so if a search term is in the document more then that, the Score result will stay at 100.

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  • An Epic Question "How to call a method when the page loads"

    - by Arunkumar Ramamoorthy
    Quite often, there comes a question in OTN, with different subjects, all meaning "How to call a method when my ADF page loads?". More often, people tend to take the approach of ADF Phase Listener by overriding before/afterPhase methods.In this blog, we will go through different options in achieving it.1. Method Call Activity as default activity in Taskflow :If the application is built with taskflows, then this is the best suited approach to take. 1.a. Calling a Data Control Method :To call a Data Control method (ex: A method in AMImpl exposed as client interface), simply Drag and Drop the method as Default Method Call Activity, then draw a control flow case from the method to your page. Once after this, drop the taskflow as region in main page. When we run the main page, the Method Call Activity would be called first, and then the page will be rendered.1.b. Calling a Method in Backing Bean: To call a method in the backing bean before pageload, we can follow the similar approach as above. Instead of binding the Method Call Activity to an action/method binding in pagedef, we bind to the method. Insert a Method Call Activity (and make it as default) from the Component Palette. Double click on to select a method to bind. This approach can also be used, to perform some action in backing bean along with calling a method Data Control (just need to add bindings code in backing bean to execute DC method). 2. Using invokeAction Executable :If the application is built with pages and no taskflows are involved, then this option can be taken into consideration.In the page definition of the page, add an invokeAction Executable and bind it to the method needed to be executed. 3. Using combination of Server and Client Listeners : If the page does not have any page definition, then to call a method in backing bean, this approach can be taken. In this, a serverListener would be added at the document level, which would be calling the method in backing bean. Along with this, a clientListener would be added with "load" type (i.e will be triggered when the page loads), which would queue a serverEvent to trigger the method. 4. Using Page Phase Listener :This should be the last resort. Care should be taken when using this approach since the Phase Listener would be called for each request sent by the client.Zeeshan Baig's blog covers this scenario.

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  • An Epic Question "How to call a method when the page loads"

    - by Arunkumar Ramamoorthy
    Quite often, there comes a question in OTN, with different subjects, all meaning "How to call a method when my ADF page loads?". More often, people tend to take the approach of ADF Phase Listener by overriding before/afterPhase methods.In this blog, we will go through different options in achieving it.1. Method Call Activity as default activity in Taskflow :If the application is built with taskflows, then this is the best suited approach to take. 1.a. Calling a Data Control Method :To call a Data Control method (ex: A method in AMImpl exposed as client interface), simply Drag and Drop the method as Default Method Call Activity, then draw a control flow case from the method to your page. Once after this, drop the taskflow as region in main page. When we run the main page, the Method Call Activity would be called first, and then the page will be rendered.1.b. Calling a Method in Backing Bean: To call a method in the backing bean before pageload, we can follow the similar approach as above. Instead of binding the Method Call Activity to an action/method binding in pagedef, we bind to the method. Insert a Method Call Activity (and make it as default) from the Component Palette. Double click on to select a method to bind. This approach can also be used, to perform some action in backing bean along with calling a method Data Control (just need to add bindings code in backing bean to execute DC method). 2. Using invokeAction Executable :If the application is built with pages and no taskflows are involved, then this option can be taken into consideration.In the page definition of the page, add an invokeAction Executable and bind it to the method needed to be executed. 3. Using combination of Server and Client Listeners : If the page does not have any page definition, then to call a method in backing bean, this approach can be taken. In this, a serverListener would be added at the document level, which would be calling the method in backing bean. Along with this, a clientListener would be added with "load" type (i.e will be triggered when the page loads), which would queue a serverEvent to trigger the method. 4. Using Page Phase Listener :This should be the last resort. Care should be taken when using this approach since the Phase Listener would be called for each request sent by the client.Zeeshan Baig's blog covers this scenario.

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  • Liskov principle: violation by type-hinting

    - by Elias Van Ootegem
    According to the Liskov principle, a construction like the one below is invalid, as it strengthens a pre-condition. I know the example is pointless/nonsense, but when I last asked a question like this, and used a more elaborate code sample, it seemed to distract people too much from the actual question. //Data models abstract class Argument { protected $value = null; public function getValue() { return $this->value; } abstract public function setValue($val); } class Numeric extends Argument { public function setValue($val) { $this->value = $val + 0;//coerce to number return $this; } } //used here: abstract class Output { public function printValue(Argument $arg) { echo $this->format($arg); return $this; } abstract public function format(Argument $arg); } class OutputNumeric extends Output { public function format(Numeric $arg)//<-- VIOLATION! { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } My question is this: Why would this kind of "violation" be considered harmful? So much so that some languages, like the one I used in this example (PHP), don't even allow this? I'm not allowed to strengthen the type-hint of an abstract method but, by overriding the printValue method, I am allowed to write: class OutputNumeric extends Output { final public function printValue(Numeric $arg) { echo $this->format($arg); } public function format(Argument $arg) { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } But this would imply repeating myself for each and every child of Output, and makes my objects harder to reuse. I understand why the Liskov principle exists, don't get me wrong, but I find it somewhat difficult to fathom why the signature of an abstract method in an abstract class has to be adhered to so much stricter than a non-abstract method. Could someone explain to me why I'm not allowed to hind at a child class, in a child class? The way I see it, the child class OutputNumeric is a specific use-case of Output, and thus might need a specific instance of Argument, namely Numeric. Is it really so wrong of me to write code like this?

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  • Base Pages and Interfaces for ASP.NET Pages

    - by geekrutherford
    For quite a while I have been using the concept of base pages when developing pages in ASP.NET applications. It is a wonderful method for exposing common functions to all of your applications pages and also overriding certain events for various purposes (i.e. dynamic themes).  Recently I found out a new developer will be joining my team. This prompted me to review the applications code for readability and ease of maintenance. I began adding comments through out the code behind for all pages within the application. While doing so I noted that I had used common method names for such things as loading data, configuring controls, applying filters, etc.   Bringing a new developer on board, I wanted to make the transition as seamless as possible while also ensuring they follow existing coding practices we already have in place. While I could have created virtual methods for the common page methods allowing them to overridden, what I really needed was a way to ensure the new developer implemented the same methods for each and every page. Thus I created an interface to force the issue.   Now, every page not only inherits the base page class but also implements an interface. This provides every page not only common functions and overridden page events but also imposes rules for implementing certain common methods :-)   Interface   public interface BasePageInterface { /// Configures page based on users security permissions. void CheckPermissions(); /// Configures Filter Form control for current page.  /// Ensure you have set the FilteredGrid and PageAjaxManager properties of the FilterForm control in PageLoad!!!  void ConfigureFilters(); /// Sets event handlers and default settings for controls on the current page. void ConfigureControls(); /// Exports data bound to grid in selected format. void ExportGridData(ExportFormat fmt); /// Loads data and binds to grid. /// Columns are turned on/off in grid depending on tab selected and users permissions.  void LoadData(); }   Page code-behind class definition:   public partial class MyPage : BasePage, BasePageInterface Note, you could not use an abstract class to accomplish this considering C# does not allow for multiple inheritance.  Nor could the base page class be abstract since it needs to inherit from the System.Web.UI.Page class in order to override page events.

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  • Representing complex object dependencies

    - by max
    I have several classes with a reasonably complex (but acyclic) dependency graph. All the dependencies are of the form: class X instance contains an attribute of class Y. All such attributes are set during initialization and never changed again. Each class' constructor has just a couple parameters, and each object knows the proper parameters to pass to the constructors of the objects it contains. class Outer is at the top of the dependency hierarchy, i.e., no class depends on it. Currently, the UI layer only creates an Outer instance; the parameters for Outer constructor are derived from the user input. Of course, Outer in the process of initialization, creates the objects it needs, which in turn create the objects they need, and so on. The new development is that the a user who knows the dependency graph may want to reach deep into it, and set the values of some of the arguments passed to constructors of the inner classes (essentially overriding the values used currently). How should I change the design to support this? I could keep the current approach where all the inner classes are created by the classes that need them. In this case, the information about "user overrides" would need to be passed to Outer class' constructor in some complex user_overrides structure. Perhaps user_overrides could be the full logical representation of the dependency graph, with the overrides attached to the appropriate edges. Outer class would pass user_overrides to every object it creates, and they would do the same. Each object, before initializing lower level objects, will find its location in that graph and check if the user requested an override to any of the constructor arguments. Alternatively, I could rewrite all the objects' constructors to take as parameters the full objects they require. Thus, the creation of all the inner objects would be moved outside the whole hierarchy, into a new controller layer that lies between Outer and UI layer. The controller layer would essentially traverse the dependency graph from the bottom, creating all the objects as it goes. The controller layer would have to ask the higher-level objects for parameter values for the lower-level objects whenever the relevant parameter isn't provided by the user. Neither approach looks terribly simple. Is there any other approach? Has this problem come up enough in the past to have a pattern that I can read about? I'm using Python, but I don't think it matters much at the design level.

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  • Identifying which pattern fits better.

    - by Daniel Grillo
    I'm developing a software to program a device. I have some commands like Reset, Read_Version, Read_memory, Write_memory, Erase_memory. Reset and Read_Version are fixed. They don't need parameters. Read_memory and Erase_memory need the same parameters that are Length and Address. Write_memory needs Lenght, Address and Data. For each command, I have the same steps in sequence, that are something like this sendCommand, waitForResponse, treatResponse. I'm having difficulty to identify which pattern should I use. Factory, Template Method, Strategy or other pattern. Edit I'll try to explain better taking in count the given comments and answers. I've already done this software and now I'm trying to refactoring it. I'm trying to use patterns, even if it is not necessary because I'm taking advantage of this little software to learn about some patterns. Despite I think that one (or more) pattern fits here and it could improve my code. When I want to read version of the software of my device, I don't have to assembly the command with parameters. It is fixed. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To read a portion of the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len and Address. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. To write a portion in the memory (maximum of 256 bytes), I have to assembly the command using the parameters Len, Address and Data. So I have to send it. After wait for response. If there is a response, treat (or parse) it and returns. I think that I could use Template Method because I have almost the same algorithm for all. But the problem is some commands are fixes, others have 2 or 3 parameters. I think that parameters should be passed on the constructor of the class. But each class will have a constructor overriding the abstract class constructor. Is this a problem for the template method? Should I use other pattern?

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