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  • Issue with my wordpress functions.php script

    - by iMayne
    Hello peeps. Im having an issues when activating my theme in wordpress. I got this error message: "Parse error: syntax error, unexpected $end in C:\xampp\htdocs\xampp\wordpress\wp-content\themes\xit\functions.php on line 223". Whats wrong, I totally dont understand. The script of the php is: <?php if ( function_exists('register_sidebar') ) register_sidebar(array( 'before_widget' => '', 'after_widget' => '', 'before_title' => '<h2>', 'after_title' => '</h2>', )); function content($num) { $theContent = get_the_content(); $output = preg_replace('/<img[^>]+./','', $theContent); $limit = $num+1; $content = explode(' ', $output, $limit); array_pop($content); $content = implode(" ",$content)."..."; echo $content; } function post_is_in_descendant_category( $cats, $_post = null ) { foreach ( (array) $cats as $cat ) { // get_term_children() accepts integer ID only $descendants = get_term_children( (int) $cat, 'category'); if ( $descendants && in_category( $descendants, $_post ) ) return true; } return false; } //custom comments function mytheme_comment($comment, $args, $depth) { $GLOBALS['comment'] = $comment; ?> <li <?php comment_class(); ?> id="li-comment-<?php comment_ID() ?>"> <div id="comment-<?php comment_ID(); ?>"> <div class="comment-author vcard"> <div class="comment-meta commentmetadata"> <?php echo get_avatar($comment,$size='32',$default='http://www.gravatar.com/avatar/61a58ec1c1fba116f8424035089b7c71?s=32&d=&r=G' ); ?> <?php printf(__('%1$s at %2$s'), get_comment_date(), get_comment_time()) ?> <br /><?php printf(__('<strong>%s</strong> says:'), get_comment_author_link()) ?><?php edit_comment_link(__('(Edit)'),' ','') ?></div> </div> <?php if ($comment->comment_approved == '0') : ?> <em><?php _e('Your comment is awaiting moderation.') ?></em> <br /> <?php endif; ?> <div class="text"><?php comment_text() ?></div> <div class="reply"> <?php comment_reply_link(array_merge( $args, array('depth' => $depth, 'max_depth' => $args['max_depth']))) ?> </div> </div> <?php } add_action('admin_menu', 'xit_theme_page'); function xit_theme_page () { if ( count($_POST) > 0 && isset($_POST['xit_settings']) ) { $options = array ( 'style','logo_img','logo_alt','logo_txt', 'logo_tagline', 'tagline_width', 'contact_email','ads', 'advertise_page', 'twitter_link', 'facebook_link', 'flickr', 'about_tit', 'about_txt', 'analytics'); foreach ( $options as $opt ) { delete_option ( 'xit_'.$opt, $_POST[$opt] ); add_option ( 'xit_'.$opt, $_POST[$opt] ); } } add_theme_page(__('Xit Options'), __('Xit Options'), 'edit_themes', basename(__FILE__), 'xit_settings'); } function xit_settings () {?> <div class="wrap"> <h2>XIT Options Panel</h2> <form method="post" action=""> <table class="form-table"> <!-- General settings --> <tr> <th colspan="2"><strong>General Settings</strong></th> </tr> <tr valign="top"> <th scope="row"><label for="style">Theme Color Scheme</label></th> <td> <select name="style" id="style"> <option value="pink.css" <?php if(get_option('xit_style') == 'pink.css'){?>selected="selected"<?php }?>>pink.css</option> <option value="blue.css" <?php if(get_option('xit_style') == 'blue.css'){?>selected="selected"<?php }?>>blue.css</option> <option value="orange.css" <?php if(get_option('xit_style') == 'orange.css'){?>selected="selected"<?php }?>>orange.css</option> </select> </td> </tr> <tr valign="top"> <th scope="row"><label for="logo_img">Logo image (full path to image)</label></th> <td> <input name="logo_img" type="text" id="logo_img" value="<?php echo get_option('xit_logo_img'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="logo_alt">Logo image ALT text</label></th> <td> <input name="logo_alt" type="text" id="logo_alt" value="<?php echo get_option('xit_logo_alt'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="logo_txt">Text logo</label></th> <td> <input name="logo_txt" type="text" id="logo_txt" value="<?php echo get_option('xit_logo_txt'); ?>" class="regular-text" /> <br /><em>Leave this empty if you entered an image as logo</em> </td> </tr> <tr valign="top"> <th scope="row"><label for="logo_tagline">Logo Tag Line</label></th> <td> <input name="logo_tagline" type="text" id="logo_tagline" value="<?php echo get_option('xit_logo_tagline'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="tagline_width">Tag Line Box Width (px)</label><br /><em style="font-size:11px">Default width: 300px</em></th> <td> <input name="tagline_width" type="text" id="tagline_width" value="<?php echo get_option('xit_tagline_width'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="contact_email">Email Address for Contact Form</label></th> <td> <input name="contact_email" type="text" id="contact_email" value="<?php echo get_option('xit_contact_email'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="twitter_link">Twitter link</label></th> <td> <input name="twitter_link" type="text" id="twitter_link" value="<?php echo get_option('xit_twitter_link'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="facebook_link">Facebook link</label></th> <td> <input name="facebook_link" type="text" id="facebook_link" value="<?php echo get_option('xit_facebook_link'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="flickr">Flickr Photostream</label></th> <td> <select name="flickr" id="flickr"> <option value="yes" <?php if(get_option('xit_flickr') == 'yes'){?>selected="selected"<?php }?>>Yes</option> <option value="no" <?php if(get_option('xit_flickr') == 'no'){?>selected="selected"<?php }?>>No</option> </select> <br /><em>Make sure you have FlickrRSS plugin activated if you choose to enable Flickr Photostream</em> </td> </tr> <!-- Sidebar ABout Box--> <tr> <th colspan="2"><strong>Sidebar About Box</strong></th> </tr> <tr valign="top"> <th scope="row"><label for="about_tit">Title</label></th> <td> <input name="about_tit" type="text" id="about_tit" value="<?php echo get_option('xit_about_tit'); ?>" class="regular-text" /> </td> </tr> <tr valign="top"> <th scope="row"><label for="about_txt">Text</label></th> <td> <textarea cols="60" rows="5" name="about_txt" type="text" id="about_txt" class="regular-text" /><?php echo get_option('xit_about_txt'); ?></textarea> </td> </tr> <!-- Ads Box Settings --> <tr> <th colspan="2"><strong>Ads Box Settings</strong></th> </tr> <tr> <th><label for="ads">Ads Section Enabled:</label></th> <td> <select name="ads" id="ads"> <option value="yes" <?php if(get_option('xit_ads') == 'yes'){?>selected="selected"<?php }?>>Yes</option> <option value="no" <?php if(get_option('xit_ads') == 'no'){?>selected="selected"<?php }?>>No</option> </select> <br /><em>Make sure you have AdMinister plugin activated and have the position "Sidebar" created within the plugin.</em> </td> </tr> <tr valign="top"> <th scope="row"><label for="advertise_page">Advertise Page</label></th> <td> <?php wp_dropdown_pages("name=advertise_page&show_option_none=".__('- Select -')."&selected=" .get_option('xit_advertise_page')); ?> </td> </tr> <!-- Google Analytics --> <tr> <th><label for="ads">Google Analytics code:</label></th> <td> <textarea name="analytics" id="analytics" rows="7" cols="70" style="font-size:11px;"><?php echo stripslashes(get_option('xit_analytics')); ?></textarea> </td> </tr> </table> <p class="submit"> <input type="submit" name="Submit" class="button-primary" value="Save Changes" /> <input type="hidden" name="xit_settings" value="save" style="display:none;" /> </p> </form> </div> <? }?> <?php function get_first_image() { global $post, $posts; $first_img = ''; ob_start(); ob_end_clean(); $output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches); $first_img = $matches [1] [0]; if(empty($first_img)){ //Defines a default image $first_img = "/images/default.jpg"; } return $first_img; } ?> The last line is line 223.

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  • How can I resolve gstreamer dependencies in Ubuntu

    - by michael
    Hi, Can you please tell me how can I resolve these dependencies on ubuntu: checking for GSTREAMER... configure: error: Package requirements (gstreamer-0.10 >= 0.10 gstreamer-app-0.10 gstreamer-base-0.10 gstreamer-pbutils-0.10 gstreamer-plugins-base-0.10 >= 0.10.25 gstreamer-video-0.10) were not met: No package 'gstreamer-app-0.10' found No package 'gstreamer-pbutils-0.10' found No package 'gstreamer-plugins-base-0.10' found No package 'gstreamer-video-0.10' found I have tried: $ sudo apt-get install *gstreamer-video* Reading package lists... Done Building dependency tree Reading state information... Done E: Regex compilation error - Invalid preceding regular expression $ sudo apt-get install *gstreamer-app* Reading package lists... Done Building dependency tree Reading state information... Done E: Regex compilation error - Invalid preceding regular expression $ sudo apt-get install *gstreamer-base* Reading package lists... Done Building dependency tree Reading state information... Done E: Regex compilation error - Invalid preceding regular expression

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  • unhandeled exception occured in c#

    - by abid
    hey. i`m getting this error that system.data.datarowview is not permitted in this contexxt. valid expressions are constants expressions and ( in some contexts). column name are not permitted.. can any body guide me what this error says.. can any one provide me a suggestion whether where im wrong.. any guesses guys??? im not getting it.. :/

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  • unhandled exception occured in c#

    - by abid
    hey. i`m getting this error that system.data.datarowview is not permitted in this contexxt. valid expressions are constants expressions and ( in some contexts). column name are not permitted.. can any body guide me what this error says.. can any one provide me a suggestion whether where im wrong.. any guesses guys??? im not getting it.. :/

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  • How to use objetcs as modules/functors in Scala?

    - by Jeff
    Hi. I want to use object instances as modules/functors, more or less as shown below: abstract class Lattice[E] extends Set[E] { val minimum: E val maximum: E def meet(x: E, y: E): E def join(x: E, y: E): E def neg(x: E): E } class Calculus[E](val lat: Lattice[E]) { abstract class Expr case class Var(name: String) extends Expr {...} case class Val(value: E) extends Expr {...} case class Neg(e1: Expr) extends Expr {...} case class Cnj(e1: Expr, e2: Expr) extends Expr {...} case class Dsj(e1: Expr, e2: Expr) extends Expr {...} } So that I can create a different calculus instance for each lattice (the operations I will perform need the information of which are the maximum and minimum values of the lattice). I want to be able to mix expressions of the same calculus but not be allowed to mix expressions of different ones. So far, so good. I can create my calculus instances, but problem is that I can not write functions in other classes that manipulate them. For example, I am trying to create a parser to read expressions from a file and return them; I also was trying to write an random expression generator to use in my tests with ScalaCheck. Turns out that every time a function generates an Expr object I can't use it outside the function. Even if I create the Calculus instance and pass it as an argument to the function that will in turn generate the Expr objects, the return of the function is not recognized as being of the same type of the objects created outside the function. Maybe my english is not clear enough, let me try a toy example of what I would like to do (not the real ScalaCheck generator, but close enough). def genRndExpr[E](c: Calculus[E], level: Int): Calculus[E]#Expr = { if (level > MAX_LEVEL) { val select = util.Random.nextInt(2) select match { case 0 => genRndVar(c) case 1 => genRndVal(c) } } else { val select = util.Random.nextInt(3) select match { case 0 => new c.Neg(genRndExpr(c, level+1)) case 1 => new c.Dsj(genRndExpr(c, level+1), genRndExpr(c, level+1)) case 2 => new c.Cnj(genRndExpr(c, level+1), genRndExpr(c, level+1)) } } } Now, if I try to compile the above code I get lots of error: type mismatch; found : plg.mvfml.Calculus[E]#Expr required: c.Expr case 0 = new c.Neg(genRndExpr(c, level+1)) And the same happens if I try to do something like: val boolCalc = new Calculus(Bool) val e1: boolCalc.Expr = genRndExpr(boolCalc) Please note that the generator itself is not of concern, but I will need to do similar things (i.e. create and manipulate calculus instance expressions) a lot on the rest of the system. Am I doing something wrong? Is it possible to do what I want to do? Help on this matter is highly needed and appreciated. Thanks a lot in advance.

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  • lexers vs parsers

    - by Naveen
    Are lexers and parsers really that different in theory ? It seems fashionable to hate regular expressions: coding horror, another blog post. However, popular lexing based tools: pygments, geshi, or prettify, all use regular expressions. They seem to lex anything... When is lexing enough, when do you need EBNF ? Has anyone used the tokens produced by these lexers with bison or antlr parser generators?

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  • Is there way to scan a registry hive on an attached USB drive?

    - by johnny
    I have a hard drive with a virus that I removed from a PC. I can scan the file system of it as an attached USB drive. But how do I scan the registry of that USB drive since it is not booted up like a regular hard drive? Thank you EDIT: To clarify, the USB drive was a regular hard drive in a PC that got infected. I cannot boot into the OS to run a scan. I removed it to attach it to a working PC so I can scan its file system. But, I cannot scan the registry of that hard drive because that drive is not booted up. The hard drive was a regular XP hard drive install that I removed to scan as an attached drive (with an adapter to make it a USB drive.)

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  • What exactly are administrative redexes after CPS conversion?

    - by eljenso
    In the context of Scheme and CPS conversion, I'm having a little trouble deciding what administrative redexes (lambdas) exactly are: all the lambda expressions that are introduced by the CPS conversion only the lambda expressions that are introduced by the CPS conversion but you wouldn't have written if you did the conversion "by hand" or through a smarter CPS-converter If possible, a good reference would be welcome.

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  • VSTS 2008 Database Edition doesn't seem to know 'DATEADD' constants, any ideas?

    - by Marcel Marchon
    I'm trying to implement a database build using VSTS 2008 Database Edition. The build always fails on the following constraint: ALTER TABLE [dbo].[tablename] ADD CONSTRAINT [DF_tablename_date] DEFAULT (CONVERT([varchar],dateadd(hour,(-1),getdate()),(1))) FOR [date]; The error that it shows is the following: TSD03082: The name "hour" is not permitted in this context. Valid expressions are constants, constant expressions, and (in some contexts) variables. Column names are not permitted. Anybody have an idea what is wrong here?

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  • Best way to get back to using the power of lxml after having to use a regex to find something in an

    - by PyNEwbie
    I am trying to rip some text out of a large number of html documents (numbers in the hundreds of thousands). The documents are really forms but they are prepared by a very large group of different organizations so there is significant variation in how they create the document. For example, the documents are divided into chapters. I might want to extract the contents of Chapter 5 from every document so I can analyze the content of the chapter. Initially I thought this would be easy but it turns out that the authors might use a set of non-nested tables throughout the document to hold the content so that Chapter n could be displayed using td tags inside a table. Or they might use other elements such as p tags H tags, div tags or any other block level element. After trying repeatedly to use lxml to help me identify the beginning and end of each chapter I have determined that it is a lot cleaner to use a regular expression because in every case, no matter what the enclosing html element is the chapter label is always in the form of >Chapter # It is a little more complicated in that there might be some white space or non-breaking space represented in different ways (  or   or just spaces). Nonetheless it was trivial to write a regular expression to identify the beginning of each section. (The beginning of one section is the end of the previous section.) But now I want to use lxml to get the text out. My thought is that I have really no choice but to walk along my string to find the close tag for the element that encloses the text I am using to find the relevant section. That is here is one example where the element holding the Chapter name is a div <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Chapter 1.&#160;&#160;&#160;Our Beginnings.</font></div> So I am imagining that I would begin at the location where I found the match for chapter 1 and set up a regular expressions to find the next </div|</td|</p|</h1 . . . So at this point I have identified the type of element holding my chapter heading I can use the same logic to find all of the text that is within that element that is set up a regular expression to help me mark from >Chapter 1.&#160;&#160;&#160;Our Beginnings.< So I have identified where my Chapter 1 begins I can do the same for chapter 2 (which is where Chapter 1 ends) Now I am imagining that I am going to snip the document beginning at the opening of the element that I identified as the element the indicates where chapter 1 begins and ending just before the opening of the element that I identified as the element that indicates where Chapter 2 begins. The string that I have identified will then be fed to lxml to use its power to get the content. I am going to all of this trouble because I have read over and over - never use a regular expression to extract content from html documents and I have not hit on a way to be as accurate with lxml to identify the starting and ending locations for the text I want to extract. For example, I can never be certain that the subtitle of Chapter 1 is Our Beginnings it could be Our Red Canary. Let me say that I spent two solid days trying with lxml to be confident that I had the beginning and ending elements and I could only be accurate <60% of the time but a very short regular expression has given me better than 95% success. I have a tendency to make things more complicated than necessary so I am wondering if anyone has seen or solved a similar problems and if they had an approach (not the details mind you) that they would like to offer.

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  • ANTLR, Dynamic variables

    - by JTS
    Hello, I have an ANTLR grammar that can parse and evaluate simple expressions like 1+2*4, etc. What I would like to do is to evaluate expressions like 2+$a-$b/4 where the $ variables are dynamic variables, that come from an external source and are continuously updated. Is there any design pattern on how to do this using ANTLR, best practices, etc? Shall I "substring" the $a with the updated value ($a - 4.34) A nicer way to do this? Thx

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  • When I type certain characters, they come out as backquotes

    - by JXG
    Very strange behavior. Some background: I bought a new lenovo G550 laptop, running Windows 7. I live in Israel. When I type certain keys, in any application, they are prefaced with the backquote (`). These characters are: Insert, Delete, Left Ctrl (the right-hand one is fine), - (the regular dash: the one on the keypad is fine), =, 5 (the regular one), 4 (the one on the numeric keypad, whether or not Num Lock is on), and PgDn (the regular one). When I press the Fn key with these I don't get the behavior. Does anyone know why this is happening, or how I can fix it?

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  • extract all urls from a string

    - by codemonkey12
    I have a string of text that contains html, and I need to extract each url (most likely in img or a tags) to create a generic list of string objects. Is there an easy way to do this or will I have to resort to regular expressions? If I have to resort to regular expressions, would you mind helping me out with that as well? :)

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  • How to match parameter names in an expression?

    - by burak ozdogan
    Hi, I have a set of expressions representing some formula with some parameters inside. Like: [parameter1] * [parameter2] * [multiplier] And many others like this. I want to use a regular expression so that I can get a list of strings (List<string>) which will have the following inside: [paramter1] [paramter2] [multiplier] I am not using regular expressions so often; if you have already used something like this I would appreciate if you can share. Thanks!

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  • Xpath visualization

    - by JavaRocky
    I am looking for a XML tool which does the following things. Allows me to enter xpath expressions and highlights the nodes selected Assists me in creating complex xpath expressions. What are other people using out there? I've used something from source forge but it only selects one matched node.

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  • Fix: Azure Disabled over 49 cents? Beware of using a Java Virtual Machine on Microsoft Azure

    - by Ken Cox [MVP]
    I love my MSDN Azure account. I can spin up a demo/dev app or VM in seconds. In fact, it is so easy to create a virtual machine that Azure shut down my whole account! Last night I spun up a Java Virtual Machine to play with some Android stuff. My mistake was that I didn’t read the Virtual Machine pricing warning: “I have a MSDN Azure Benefit subscription. Can I use my monthly Azure credits to purchase Oracle software?” “No, Azure credits in our MSDN offers are not applicable to Oracle software. In order to purchase Oracle software in the MSDN Azure Benefit subscription, customers need to turn off their {0} spending limit and pay at the regular pay-as-you-go rate. Otherwise, Oracle usage will hit the {1} spending limit and the subscription will be immediately disabled.”  Immediately disabled? Yup. Everything connected to the subscription was shut off, deallocated, rendered useless - even the free Web sites and the free Sendgrid email service.  The fix? I had to remove the spending limit from my account so I could pay $0.49 (49 cents) for the JVM usage. I still had $134.10 in credits remaining for regular usage with 6 days left in the billing month.  Now the restoration/clean-up begins… figuring out how to get the web sites and services back online.  To me, the preferable way would be for Azure to warn me when setting up a JVM that I had no way of paying for the service. In the alternative, shut down just the offending services – the ones that can’t be covered by the regular credits. What a mess.

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  • Need help with ColdFusion and ASP.NET site [closed]

    - by Michael Stone
    To begin, I wasn't too sure how to title this.. I've got a few questions. First off, I've got a very big site that's in ColdFusion and we've been migrating to ASP.NET C# 4.0 the last 8 months. I've got a team of 7 programmers and no one can seem to figure out these answers, not even our senior C# programmer. We're using Team Foundation Server and we can't figure out how to only push up one small change at time. Right now we're stuck to publishing the entire site and it's causing serious issues. We've currently got the site as a Project and not a Website. We're wondering if that's one issue. I actually think it might be a problem. We're also dealing with an issue where we can't access our regular folders with relative paths. So we're first developing our admin side in .NET and We've got our regular site and then we've got another site within that for our .NET admin tools. By site, I'm referring to them actually being Sites in IIS. This also creates a problem for us when we're creating tools that upload images and want to store them and access them from our parent Site. I'd very much appreciate any advice on how to go about this in the most standardized way. So what I'm hoping for is advise on: -Publishing and managing a site/project in Team Foundation Server. Being able to push up one fix at a time if needed would be GREAT! -Any help figuring out the issuing referencing folders from my .NET child site to my parent ColdFusion site using regular relative paths. "/a/images/b/" would be nice nice instead of only being able to do "/b/images/" We're using ColdFusion 8, C# Asp.NET 4.0/Entity Framework/POCO Templates, and a Windows 2008 R2 Server. Thank you in advance for any help.

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  • How to handle fine grained field-based ACL permissions in a RESTful service?

    - by Jason McClellan
    I've been trying to design a RESTful API and have had most of my questions answered, but there is one aspect of permissions that I'm struggling with. Different roles may have different permissions and different representations of a resource. For example, an Admin or the user himself may see more fields in his own User representation vs another less-privileged user. This is achieved simply by changing the representation on the backend, ie: deciding whether or not to include those fields. Additionally, some actions may be taken on a resource by some users and not by others. This is achieved by deciding whether or not to include those action items as links, eg: edit and delete links. A user who does not have edit permissions will not have an edit link. That covers nearly all of my permission use cases, but there is one that I've not quite figured out. There are some scenarios whereby for a given representation of an object, all fields are visible for two or more roles, but only a subset of those roles my edit certain fields. An example: { "person": { "id": 1, "name": "Bob", "age": 25, "occupation": "software developer", "phone": "555-555-5555", "description": "Could use some sunlight.." } } Given 3 users: an Admin, a regular User, and Bob himself (also a regular User), I need to be able to convey to the front end that: Admins may edit all fields, Bob himself may edit all fields, but a regular User, while they can view all fields, can only edit the description field. I certainly don't want the client to have to make the determination (or even, for that matter, to have any notion of the roles involved) but I do need a way for the backend to convey to the client which fields are editable. I can't simply use a combination of representation (the fields returned for viewing) and links (whether or not an edit link is availble) in this scenario since it's more finely grained. Has anyone solved this elegantly without adding the logic directly to the client?

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  • ASP.NET MVC 3: Implicit and Explicit code nuggets with Razor

    - by ScottGu
    This is another in a series of posts I’m doing that cover some of the new ASP.NET MVC 3 features: New @model keyword in Razor (Oct 19th) Layouts with Razor (Oct 22nd) Server-Side Comments with Razor (Nov 12th) Razor’s @: and <text> syntax (Dec 15th) Implicit and Explicit code nuggets with Razor (today) In today’s post I’m going to discuss how Razor enables you to both implicitly and explicitly define code nuggets within your view templates, and walkthrough some code examples of each of them.  Fluid Coding with Razor ASP.NET MVC 3 ships with a new view-engine option called “Razor” (in addition to the existing .aspx view engine).  You can learn more about Razor, why we are introducing it, and the syntax it supports from my Introducing Razor blog post. Razor minimizes the number of characters and keystrokes required when writing a view template, and enables a fast, fluid coding workflow. Unlike most template syntaxes, you do not need to interrupt your coding to explicitly denote the start and end of server blocks within your HTML. The Razor parser is smart enough to infer this from your code. This enables a compact and expressive syntax which is clean, fast and fun to type. For example, the Razor snippet below can be used to iterate a collection of products and output a <ul> list of product names that link to their corresponding product pages: When run, the above code generates output like below: Notice above how we were able to embed two code nuggets within the content of the foreach loop.  One of them outputs the name of the Product, and the other embeds the ProductID within a hyperlink.  Notice that we didn’t have to explicitly wrap these code-nuggets - Razor was instead smart enough to implicitly identify where the code began and ended in both of these situations.  How Razor Enables Implicit Code Nuggets Razor does not define its own language.  Instead, the code you write within Razor code nuggets is standard C# or VB.  This allows you to re-use your existing language skills, and avoid having to learn a customized language grammar. The Razor parser has smarts built into it so that whenever possible you do not need to explicitly mark the end of C#/VB code nuggets you write.  This makes coding more fluid and productive, and enables a nice, clean, concise template syntax.  Below are a few scenarios that Razor supports where you can avoid having to explicitly mark the beginning/end of a code nugget, and instead have Razor implicitly identify the code nugget scope for you: Property Access Razor allows you to output a variable value, or a sub-property on a variable that is referenced via “dot” notation: You can also use “dot” notation to access sub-properties multiple levels deep: Array/Collection Indexing: Razor allows you to index into collections or arrays: Calling Methods: Razor also allows you to invoke methods: Notice how for all of the scenarios above how we did not have to explicitly end the code nugget.  Razor was able to implicitly identify the end of the code block for us. Razor’s Parsing Algorithm for Code Nuggets The below algorithm captures the core parsing logic we use to support “@” expressions within Razor, and to enable the implicit code nugget scenarios above: Parse an identifier - As soon as we see a character that isn't valid in a C# or VB identifier, we stop and move to step 2 Check for brackets - If we see "(" or "[", go to step 2.1., otherwise, go to step 3  Parse until the matching ")" or "]" (we track nested "()" and "[]" pairs and ignore "()[]" we see in strings or comments) Go back to step 2 Check for a "." - If we see one, go to step 3.1, otherwise, DO NOT ACCEPT THE "." as code, and go to step 4 If the character AFTER the "." is a valid identifier, accept the "." and go back to step 1, otherwise, go to step 4 Done! Differentiating between code and content Step 3.1 is a particularly interesting part of the above algorithm, and enables Razor to differentiate between scenarios where an identifier is being used as part of the code statement, and when it should instead be treated as static content: Notice how in the snippet above we have ? and ! characters at the end of our code nuggets.  These are both legal C# identifiers – but Razor is able to implicitly identify that they should be treated as static string content as opposed to being part of the code expression because there is whitespace after them.  This is pretty cool and saves us keystrokes. Explicit Code Nuggets in Razor Razor is smart enough to implicitly identify a lot of code nugget scenarios.  But there are still times when you want/need to be more explicit in how you scope the code nugget expression.  The @(expression) syntax allows you to do this: You can write any C#/VB code statement you want within the @() syntax.  Razor will treat the wrapping () characters as the explicit scope of the code nugget statement.  Below are a few scenarios where we could use the explicit code nugget feature: Perform Arithmetic Calculation/Modification: You can perform arithmetic calculations within an explicit code nugget: Appending Text to a Code Expression Result: You can use the explicit expression syntax to append static text at the end of a code nugget without having to worry about it being incorrectly parsed as code: Above we have embedded a code nugget within an <img> element’s src attribute.  It allows us to link to images with URLs like “/Images/Beverages.jpg”.  Without the explicit parenthesis, Razor would have looked for a “.jpg” property on the CategoryName (and raised an error).  By being explicit we can clearly denote where the code ends and the text begins. Using Generics and Lambdas Explicit expressions also allow us to use generic types and generic methods within code expressions – and enable us to avoid the <> characters in generics from being ambiguous with tag elements. One More Thing….Intellisense within Attributes We have used code nuggets within HTML attributes in several of the examples above.  One nice feature supported by the Razor code editor within Visual Studio is the ability to still get VB/C# intellisense when doing this. Below is an example of C# code intellisense when using an implicit code nugget within an <a> href=”” attribute: Below is an example of C# code intellisense when using an explicit code nugget embedded in the middle of a <img> src=”” attribute: Notice how we are getting full code intellisense for both scenarios – despite the fact that the code expression is embedded within an HTML attribute (something the existing .aspx code editor doesn’t support).  This makes writing code even easier, and ensures that you can take advantage of intellisense everywhere. Summary Razor enables a clean and concise templating syntax that enables a very fluid coding workflow.  Razor’s ability to implicitly scope code nuggets reduces the amount of typing you need to perform, and leaves you with really clean code. When necessary, you can also explicitly scope code expressions using a @(expression) syntax to provide greater clarity around your intent, as well as to disambiguate code statements from static markup. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Using delegates in C# (Part 2)

    - by rajbk
    Part 1 of this post can be read here. We are now about to see the different syntaxes for invoking a delegate and some c# syntactic sugar which allows you to code faster. We have the following console application. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Operation op1 = new Operation(Division); 9: double result = op1.Invoke(10, 5); 10: 11: Console.WriteLine(result); 12: Console.ReadLine(); 13: } 14: 15: static double Division(double x, double y) { 16: return x / y; 17: } 18: } Line 1 defines a delegate type called Operation with input parameters (double x, double y) and a return type of double. On Line 8, we create an instance of this delegate and set the target to be a static method called Division (Line 15) On Line 9, we invoke the delegate (one entry in the invocation list). The program outputs 5 when run. The language provides shortcuts for creating a delegate and invoking it (see line 9 and 11). Line 9 is a syntactical shortcut for creating an instance of the Delegate. The C# compiler will infer on its own what the delegate type is and produces intermediate language that creates a new instance of that delegate. Line 11 uses a a syntactical shortcut for invoking the delegate by removing the Invoke method. The compiler sees the line and generates intermediate language which invokes the delegate. When this code is compiled, the generated IL will look exactly like the IL of the compiled code above. 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //shortcut constructor syntax 9: Operation op1 = Division; 10: //shortcut invoke syntax 11: double result = op1(10, 2); 12: 13: Console.WriteLine(result); 14: Console.ReadLine(); 15: } 16: 17: static double Division(double x, double y) { 18: return x / y; 19: } 20: } C# 2.0 introduced Anonymous Methods. Anonymous methods avoid the need to create a separate method that contains the same signature as the delegate type. Instead you write the method body in-line. There is an interesting fact about Anonymous methods and closures which won’t be covered here. Use your favorite search engine ;-)We rewrite our code to use anonymous methods (see line 9): 1: public delegate double Operation(double x, double y); 2:  3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: //Anonymous method 9: Operation op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } We could rewrite our delegate to be of a generic type like so (see line 2 and line 9). You will see why soon. 1: //Generic delegate 2: public delegate T Operation<T>(T x, T y); 3:  4: public class Program 5: { 6: [STAThread] 7: static void Main(string[] args) 8: { 9: Operation<double> op1 = delegate(double x, double y) { 10: return x / y; 11: }; 12: double result = op1(10, 2); 13: 14: Console.WriteLine(result); 15: Console.ReadLine(); 16: } 17: 18: static double Division(double x, double y) { 19: return x / y; 20: } 21: } The .NET 3.5 framework introduced a whole set of predefined delegates for us including public delegate TResult Func<T1, T2, TResult>(T1 arg1, T2 arg2); Our code can be modified to use this delegate instead of the one we declared. Our delegate declaration has been removed and line 7 has been changed to use the Func delegate type. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //Func is a delegate defined in the .NET 3.5 framework 7: Func<double, double, double> op1 = delegate (double x, double y) { 8: return x / y; 9: }; 10: double result = op1(10, 2); 11: 12: Console.WriteLine(result); 13: Console.ReadLine(); 14: } 15: 16: static double Division(double x, double y) { 17: return x / y; 18: } 19: } .NET 3.5 also introduced lambda expressions. A lambda expression is an anonymous function that can contain expressions and statements, and can be used to create delegates or expression tree types. We change our code to use lambda expressions. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //lambda expression 7: Func<double, double, double> op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } C# 3.0 introduced the keyword var (implicitly typed local variable) where the type of the variable is inferred based on the type of the associated initializer expression. We can rewrite our code to use var as shown below (line 7).  The implicitly typed local variable op1 is inferred to be a delegate of type Func<double, double, double> at compile time. 1: public class Program 2: { 3: [STAThread] 4: static void Main(string[] args) 5: { 6: //implicitly typed local variable 7: var op1 = (x, y) => x / y; 8: double result = op1(10, 2); 9: 10: Console.WriteLine(result); 11: Console.ReadLine(); 12: } 13: 14: static double Division(double x, double y) { 15: return x / y; 16: } 17: } You have seen how we can write code in fewer lines by using a combination of the Func delegate type, implicitly typed local variables and lambda expressions.

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