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  • help merging perl code routines together for file processing

    - by jdamae
    I need some perl help in putting these (2) processes/code to work together. I was able to get them working individually to test, but I need help bringing them together especially with using the loop constructs. I'm not sure if I should go with foreach..anyways the code is below. Also, any best practices would be great too as I'm learning this language. Thanks for your help. Here's the process flow I am looking for: -read a directory -look for a particular file -use the file name to strip out some key information to create a newly processed file -process the input file -create the newly processed file for each input file read (if i read in 10, I create 10 new files) Sample Recs: col1,col2,col3,col4,col5 [email protected],[email protected],8,2009-09-24 21:00:46,1 [email protected],[email protected],16,2007-08-18 22:53:12,33 [email protected],[email protected],16,2007-08-18 23:41:23,33 Here's my test code: Target Filetype: `/backups/test/foo101.name.aue-foo_p002.20110124.csv` Part 1: my $target_dir = "/backups/test/"; opendir my $dh, $target_dir or die "can't opendir $target_dir: $!"; while (defined(my $file = readdir($dh))) { next if ($file =~ /^\.+$/); #Get filename attributes if ($file =~ /^foo(\d{3})\.name\.(\w{3})-foo_p(\d{1,4})\.\d+.csv$/) { print "$1\n"; print "$2\n"; print "$3\n"; } print "$file\n"; } Part 2: use strict; use Digest::MD5 qw(md5_hex); #Create new file open (NEWFILE, ">/backups/processed/foo$1.name.$2-foo_p$3.out") || die "cannot create file"; my $data = ''; my $line1 = <>; chomp $line1; my @heading = split /,/, $line1; my ($sep1, $sep2, $eorec) = ( "^A", "^E", "^D"); while (<>) { my $digest = md5_hex($data); chomp; my (@values) = split /,/; my $extra = "__mykey__$sep1$digest$sep2" ; $extra .= "$heading[$_]$sep1$values[$_]$sep2" for (0..scalar(@values)); $data .= "$extra$eorec"; print NEWFILE "$data"; } #print $data; close (NEWFILE);

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  • How to find the one Label in DataList that is set to True

    - by Doug
    In my .aspx page I have my DataList: <asp:DataList ID="DataList1" runat="server" DataKeyField="ProductSID" DataSourceID="SqlDataSource1" onitemcreated="DataList1_ItemCreated" RepeatColumns="3" RepeatDirection="Horizontal" Width="1112px"> <ItemTemplate> ProductSID: <asp:Label ID="ProductSIDLabel" runat="server" Text='<%# Eval("ProductSID") %>' /> <br /> ProductSKU: <asp:Label ID="ProductSKULabel" runat="server" Text='<%# Eval("ProductSKU") %>' /> <br /> ProductImage1: <asp:Label ID="ProductImage1Label" runat="server" Text='<%# Eval("ProductImage1") %>' /> <br /> ShowLive: <asp:Label ID="ShowLiveLabel" runat="server" Text='<%# Eval("ShowLive") %>' /> <br /> CollectionTypeID: <asp:Label ID="CollectionTypeIDLabel" runat="server" Text='<%# Eval("CollectionTypeID") %>' /> <br /> CollectionHomePage: <asp:Label ID="CollectionHomePageLabel" runat="server" Text='<%# Eval("CollectionHomePage") %>' /> <br /> <br /> </ItemTemplate> </asp:DataList> And in my code behind using the ItemCreated event to find and set the label.backcolor property. (Note:I'm using a recursive findControl class) protected void DataList1_ItemCreated(object sender, DataListItemEventArgs e) { foreach (DataListItem item in DataList1.Items) { if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem) { Label itemLabel = form1.FindControlR("CollectionHomePageLabel") as Label; if (itemLabel !=null || itemLabel.Text == "True") { itemLabel.BackColor = System.Drawing.Color.Yellow; } } When I run the page, the itemLabel is found, and the color shows. But it sets the itemLabel color to the first instance of the itemLabel found in the DataList. Of all the itemLabels in the DataList, only one will have it's text = True - and that should be the label picking up the backcolor. Also: The itemLabel is picking up a column in the DB called "CollectionHomePage" which is True/False bit data type. I must be missing something simple... Thanks for your ideas.

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  • How do I code a loop for my echo statements?

    - by ggg
    <?php defined('_JEXEC') or die('Restricted access'); $db =& JFactory::getDBO(); $query0 = "SELECT * FROM `#__chesspositions` WHERE . . . . ."; //echo $query0; $db->setQuery($query0); $ginfo = $db->loadObjectList(); //echo $ginfo[0]; echo $db->getErrorMsg(); if(empty($ginfo)){ echo "<center><h2 style='color:navy'>No game found, we apologize</h2></center>"; }else{ $query1= "SELECT * FROM `#__chessmoves` WHERE Id='".$ginfo[0]->MoveDataId."'"; $db->setQuery($query1); echo $db->getErrorMsg(); $gmove = $db->loadObjectList(); } //define array; //how do I code a foreach loop (or any other type of loop) here? //I'm having trouble properly defining the array and structuring the syntax. echo "[Event \"".$ginfo[0]->Event."\"]\n"; echo "[Site \"".$ginfo[0]->Site."\"]\n"; echo "[Date \"".$ginfo[0]->Date."\"]\n"; echo "[Round \"".$ginfo[0]->Round."\"]\n"; echo "[White \"".$ginfo[0]->White."\"]\n"; echo "[Black \"".$ginfo[0]->Black."\"]\n"; echo "[Result \"".$ginfo[0]->Result."\"]\n"; echo "[ECO \"".$ginfo[0]->ECO."\"]\n"; echo "[WhiteElo \"".$ginfo[0]->WhiteElo."\"]\n"; echo "[BlackElo \"".$ginfo[0]->BlackElo."\"]\n"; echo "[Annotator \"".$ginfo[0]->Annotator."\"]\n"; echo "[SetUp \"".$ginfo[0]->SetUp."\"]\n"; echo $gmove[0]->MoveData; ?>

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  • Generating Unordered List with PHP + CodeIgniter from a MySQL Database

    - by Tim
    Hello Everyone, I am trying to build a dynamically generated unordered list in the following format using PHP. I am using CodeIgniter but it can just be normal php. This is the end output I need to achieve. <ul id="categories" class="menu"> <li rel="1"> Arts &amp; Humanities <ul> <li rel="2"> Photography <ul> <li rel="3"> 3D </li> <li rel="4"> Digital </li> </ul> </li> <li rel="5"> History </li> <li rel="6"> Literature </li> </ul> </li> <li rel="7"> Business &amp; Economy </li> <li rel="8"> Computers &amp; Internet </li> <li rel="9"> Education </li> <li rel="11"> Entertainment <ul> <li rel="12"> Movies </li> <li rel="13"> TV Shows </li> <li rel="14"> Music </li> <li rel="15"> Humor </li> </ul> </li> <li rel="10"> Health </li> And here is my SQL that I have to work with. -- -- Table structure for table `categories` -- CREATE TABLE IF NOT EXISTS `categories` ( `id` mediumint(8) NOT NULL auto_increment, `dd_id` mediumint(8) NOT NULL, `parent_id` mediumint(8) NOT NULL, `cat_name` varchar(256) NOT NULL, `cat_order` smallint(4) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; So I know that I am going to need at least 1 foreach loop to generate the first level of categories. What I don't know is how to iterate inside each loop and check for parents and do that in a dynamic way so that there could be an endless tree of children. Thanks for any help you can offer. Tim

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  • How do I create a loop based off this array?

    - by dmanexe
    I'm trying to process this array, first testing for the presence of a check, then extrapolating the data from quantity to return a valid price. Here's the input for fixed amounts of items, with no variable quantity. <input type="checkbox" name="measure[<?=$item->id?>][checked]" value="<?=$item->id?>"> <input type="hidden" name="measure[<?=$item->id?>][quantity]" value="1" /> Here's the inputs for variable amounts of items. <input type="checkbox" name="measure[<?=$item->id?>][checked]" value="<?=$item->id?>"> <input class="item_mult" value="0" type="text" name="measure[<?=$item->id?>][quantity]" /> So, the resulting array is multidimensional. Here's an output: Array ( [1] => Array ( [quantity] => 1 ) [2] => Array ( [quantity] => 1 ) [3] => Array ( [quantity] => 1 ) ... [14] => Array ( [checked] => 14 [quantity] => 999 ) ) Here's the loop I'm using to take this array and process items checked off the form in the first place. I guess the question essentially boils down to how do I structure my conditional statement to incorporate the multi-dimensional array? foreach($field as $value): if ($value['checked'] == TRUE) { $query = $this->db->get_where('items', array('id' => $value['checked']))->row(); #Test to see if quantity input is present if ($value['quantity'] == TRUE) { $newprice = $value['quantity'] * $query->price; $totals[] = $newprice; } #Just return the base value if not else { $newprice = $query->price; $totals[] = $newprice; } } else { } ?> <p><?=$query->name?> - <?=money_format('%(#10n', $newprice)?></p> <? endforeach; ?>

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  • php loop xml data with xsd schema - how do get the data

    - by miholzi
    i try to geht the data from a xml file and i have troubles to get data, for example, how can i get the caaml:locRef value or the caaml:beginPosition value? here is the code so far: /* a big thank you to helderdarocha */ /* – he already helped me yesterday with a part of this code */ $doc = new DOMDocument(); $doc->load('xml/test.xml'); $xpath = new DOMXpath($doc); $xpath->registerNamespace("caaml", "http://caaml.org/Schemas/V5.0/Profiles/BulletinEAWS"); if ($doc->schemaValidate('http://caaml.org/Schemas/V5.0/Profiles/BulletinEAWS/CAAMLv5_BulletinEAWS.xsd')) { foreach ($xpath->query('//caaml:DangerRating') as $key) { echo $key->nodeValue; print_r($key); } } and here ist the print_r from $key DOMElement Object ( [tagName] => caaml:DangerRating [schemaTypeInfo] => [nodeName] => caaml:DangerRating [nodeValue] => 2014-03-03+01:00 2 [nodeType] => 1 [parentNode] => (object value omitted) [childNodes] => (object value omitted) [firstChild] => (object value omitted) [lastChild] => (object value omitted) [previousSibling] => (object value omitted) [nextSibling] => (object value omitted) [attributes] => (object value omitted) [ownerDocument] => (object value omitted) [namespaceURI] => http://caaml.org/Schemas/V5.0/Profiles/BulletinEAWS [prefix] => caaml [localName] => DangerRating [baseURI] => /Applications/MAMP/htdocs/lola/xml/test.xml [textContent] => 2014-03-03+01:00 2 ) 2014-03-04+01:00 2 and here a part of the xml <caaml:DangerRating> <caaml:locRef xlink:href="AT7R1"/> <caaml:validTime> <caaml:TimePeriod> <caaml:beginPosition>2014-03-06T00:00:00+01:00</caaml:beginPosition> <caaml:endPosition>2014-03-06T11:59:59+01:00</caaml:endPosition> </caaml:TimePeriod> </caaml:validTime> <caaml:validElevation> <caaml:ElevationRange uom="m"> <caaml:beginPosition>2200</caaml:beginPosition> </caaml:ElevationRange> </caaml:validElevation> <caaml:mainValue>2</caaml:mainValue> </caaml:DangerRating> <caaml:DangerRating> <caaml:locRef xlink:href="AT7R1"/> <caaml:validTime> <caaml:TimePeriod> thanks!

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  • One nginx rules for lots of subdomain

    - by komase
    I have lots of subdomain in a server. Every subdomain has its own Drupal boost rules, like in below codes: server { server_name subdomain1.website.com; location / { root /var/www/html/subdomain/subdomain1.website.com; index index.php; set $boost ""; set $boost_query "_"; if ( $request_method = GET ) { set $boost G; } if ($http_cookie !~ "DRUPAL_UID") { set $boost "${boost}D"; } if ($query_string = "") { set $boost "${boost}Q"; } if ( -f $document_root/cache/normal/$host$request_uri$boost_query.html ) { set $boost "${boost}F"; } if ($boost = GDQF){ rewrite ^.*$ /cache/normal/$host/$request_uri$boost_query.html break; } if (!-e $request_filename) { rewrite ^/(.*)$ /index.php?q=$1 last; break; } } location ~ \.php$ { fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME /var/www/html/subdomain/subdomain1.website.com$fastcgi_script_name; include fastcgi_params; } } I adding all subdomain rules manually from time to time. The size of ngin.conf has become too big. So, I need one nginx rules which do: subdomain1.website.com pointing to /var/www/html/subdomain/subdomain1.website.com subdomain2.website.com pointing to /var/www/html/subdomain/subdomain2.website.com subdomain3.website.com pointing to /var/www/html/subdomain/subdomain3.website.com ...and so on (So that no more adding rules for subdomain .website.com I need in the future.)

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  • Retreiving multiple rows from a loop-created form... Stuck.

    - by hangston
    Hi All, Let me start by saying that I'm new to PHP, but I'm here to learn and would really appreciate your help. I use the following code to pull in data and create a form. This creates up to 40 lines for a user to fill out. Each line consists of the same information: Description, Amount, and Frequency. The remainder of the information needed is generated by the database. (See hidden fields) <?php $row = 0; do { $optid = $row_options['option_id']; echo "<tr>\n\t<td>" . htmlentities($row_options['option']) . "</td>\n"; echo "\t<td>" . "<input name='description' type='text' size='40' maxlength='120'/>" . "</td>\n"; echo "\t<td>" . "<input name='option_id' type='hidden' value='$optid' />$<input name='amount' type='text' size='10' maxlength='7'/>" . "</td>\n"; echo "\t<td>" . "<select name='assisted_frequency'> <option value='Monthly'>Monthly</option> <option value='Weekly'>Weekly</option> <option value='Daily'>Daily</option> <option value='Hourly'>Hourly</option> <option value='One-Time'>One-Time</option> </select>" . "</td>\n</tr>\n"; $array[$row] = array( $arraydesc[$row] = $_POST['description'], $arrayamto[$row] = $_POST['amount'], $arrayoptid[$row] = $optid, $arrayfreq[$row] = $_POST['frequency'], ); $row ++; } while ($row_options = mysql_fetch_assoc($options)); $counter = $row - 1; ?> I'm having troubles retrieving the information that the user inputs. My intent is to loop through each row after the user has input their information, then upload the mix of my database information and the user's information into another database. For example, the user would see, albeit prettier: form1 Option 1: description [input box] amount [input box] frequency [option box] Option 2: description [input box] amount [input box] frequency [option box] Option 3: description [input box] amount [input box] frequency [option box] Option 4: description [input box] amount [input box] frequency [option box] submit Upon submitting the form above, I'm using a query similar to the following to input the data into the database: for($row=0; $row<=$counter; $row++){ $insertSQL2 = sprintf("INSERT INTO table (option_id, amount, description, frequency) VALUES (%s, %s, %s, %s)", GetSQLValueString($arrayoptid[$row], "int"), GetSQLValueString($arrayamto[$row], "int"), GetSQLValueString($arraydesc[$row], "text"), GetSQLValueString($arrayfreq[$row], "text")); // code to submit query } I've tried for, foreach, arrays (what feels like the everything I know) to post each row (row by row) into the database. I either get just the last row of data, or no data at all. I also worry that the [$row] technique is adding characters to my data. What is the best way to retrieve each row of the user's inputs, then upload this data (row by row) into the database? Also, I would really appreciate your suggestions for improving my coding technique and the approach I'm taking. Thank you, Hangston

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  • Retrieving multiple rows from a loop-created form... Stuck.

    - by hangston
    Let me start by saying that I'm new to PHP, but I'm here to learn and would really appreciate your help. I use the following code to pull in data and create a form. This creates up to 40 lines for a user to fill out. Each line consists of the same information: Description, Amount, and Frequency. The remainder of the information needed is generated by the database. (See hidden fields) <?php $row = 0; do { $optid = $row_options['option_id']; echo "<tr>\n\t<td>" . htmlentities($row_options['option']) . "</td>\n"; echo "\t<td>" . "<input name='description' type='text' size='40' maxlength='120'/>" . "</td>\n"; echo "\t<td>" . "<input name='option_id' type='hidden' value='$optid' />$<input name='amount' type='text' size='10' maxlength='7'/>" . "</td>\n"; echo "\t<td>" . "<select name='assisted_frequency'> <option value='Monthly'>Monthly</option> <option value='Weekly'>Weekly</option> <option value='Daily'>Daily</option> <option value='Hourly'>Hourly</option> <option value='One-Time'>One-Time</option> </select>" . "</td>\n</tr>\n"; $array[$row] = array( $arraydesc[$row] = $_POST['description'], $arrayamto[$row] = $_POST['amount'], $arrayoptid[$row] = $optid, $arrayfreq[$row] = $_POST['frequency'], ); $row ++; } while ($row_options = mysql_fetch_assoc($options)); $counter = $row - 1; ?> I'm having troubles retrieving the information that the user inputs. My intent is to loop through each row after the user has input their information, then upload the mix of my database information and the user's information into another database. For example, the user would see, albeit prettier: form1 Option 1: description [input box] amount [input box] frequency [option box] Option 2: description [input box] amount [input box] frequency [option box] Option 3: description [input box] amount [input box] frequency [option box] Option 4: description [input box] amount [input box] frequency [option box] submit Upon submitting the form above, I'm using a query similar to the following to input the data into the database: for($row=0; $row<=$counter; $row++){ $insertSQL2 = sprintf("INSERT INTO table (option_id, amount, description, frequency) VALUES (%s, %s, %s, %s)", GetSQLValueString($arrayoptid[$row], "int"), GetSQLValueString($arrayamto[$row], "int"), GetSQLValueString($arraydesc[$row], "text"), GetSQLValueString($arrayfreq[$row], "text")); // code to submit query } I've tried for, foreach, arrays (what feels like the everything I know) to post each row (row by row) into the database. I either get just the last row of data, or no data at all. I also worry that the [$row] technique is adding characters to my data. What is the best way to retrieve each row of the user's inputs, then upload this data (row by row) into the database? Also, I would really appreciate your suggestions for improving my coding technique and the approach I'm taking.

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  • Template with constant expression: error C2975 with VC++2008

    - by Arman
    Hello, I am trying to use elements of meta programming, but hit the wall with the first trial. I would like to have a comparator structure which can be used as following: intersect_by<ID>(L1.data, L2.data, "By ID: "); intersect_by<IDf>(L1.data, L2.data, "By IDf: "); Where: struct ID{};// Tag used for original IDs struct IDf{};// Tag used for the file position //following Boost.MultiIndex examples template<typename Tag,typename MultiIndexContainer> void intersect_by( const MultiIndexContainer& L1,const MultiIndexContainer& L2,std::string msg, Tag* =0 /* fixes a MSVC++ 6.0 bug with implicit template function parms / ) { / obtain a reference to the index tagged by Tag */ const typename boost::multi_index::index<MultiIndexContainer,Tag>::type& L1_ID_index= get<Tag>(L1); const typename boost::multi_index::index<MultiIndexContainer,Tag>::type& L2_ID_index= get<Tag>(L2); std::set_intersection( L1_ID_index.begin(), L1_ID_index.end(), L2_ID_index.begin(), L2_ID_index.end(), std::inserter(s, s.begin()), strComparator() // Here I get the C2975 error ); } template<int N> struct strComparator; template<> struct strComparator<0>{ bool operator () (const particleID& id1, const particleID& id2) const { return id1.ID struct strComparator<1{ bool operator () (const particleID& id1, const particleID& id2) const { return id1.IDf }; What I am missing? kind regards Arman.

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  • C++ Serialization Clean XML Similar to XSTREAM

    - by disown
    I need to write a linux c++ app which saves it settings in XML format (for easy hand editing) and also communicates with existing apps through XML messages over sockets and HTTP. Problem is that I haven't been able to find any intelligent libs to help me, I don't particular feel like writing DOM or SAX code just to write and read some very simple messages. Boost Serialization was almost a match, but it adds a lot of boost-specific data to the xml it generates. This obviously doesn't work well for interchange formats. I'm wondering if it is possible to make Boost Serialization or some other c++ serialization library generate clean xml. I don't mind if there are some required extra attributes - like a version attribute, but I'd really like to be able to control their naming and also get rid of 'features' that I don't use - tracking_level and class_id for instance. Ideally I would just like to have something similar to xstream in Java. I am aware of the fact that c++ lacks introspection and that it is therefore necessary to do some manual coding - but it would be nice if there was a clean solution to just read and write simple XML without kludges! If this cannot be done I am also interested in tools where the XML schema is the canonical resource (contract first) - a good JAXB alternative to C++. So far I have only found commercial solutions like CodeSynthesis XSD. I would prefer open source solutions. I have tried gSoap - but it generates really ugly code and it is also SOAP-specific. In desperation I also started looking at alternative serialization formats for protobuffers. This exists - but only for Java! It really surprises me that protocol buffers seems to be a better supported data interchange format than XML. I'm going mad just finding libs for this app and I really need some new ideas. Anyone?

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  • std::locale breakage on MacOS 10.6 with LANG=en_US.UTF-8

    - by fixermark
    I have a C++ application that I am porting to MacOSX (specifically, 10.6). The app makes heavy use of the C++ standard library and boost. I recently observed some breakage in the app that I'm having difficulty understanding. Basically, the boost filesystem library throws a runtime exception when the program runs. With a bit of debugging and googling, I've reduced the offending call to the following minimal program: #include <locale> int main ( int argc, char *argv [] ) { std::locale::global(std::locale("")); return 0; } This program fails when I run this through g++ and execute the resulting program in an environment where LANG=en_US.UTF-8 is set (which on my computer is part of the default bash session when I create a new console window). Clearing the environment variable (setenv LANG=) allows the program to run without issues. But I'm surprised I'm seeing this breakage in the default configuration. My questions are: Is this expected behavior for this code on MacOS 10.6? What would a proper workaround be? I can't really re-write the function because the version of the boost libraries we are using executes this statement internally as part of the filesystem library. For completeness, I should point out that the program from which this code was synthesized crashes when launched via the 'open' command (or from the Finder) but not when Xcode runs the program in Debug mode. edit The error given by the above code on 10.6.1 is: $ ./locale terminate called after throwing an instance of 'std::runtime_error' what(): locale::facet::_S_create_c_locale name not valid Abort trap

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  • How to get at contents of placeholder::_1

    - by sheepsimulator
    I currently have the following code: using boost::bind; typedef boost::signal<void(EventDataItem&)> EventDataItemSignal; class EventDataItem { ... EventDataItemSignal OnTrigger; ... } typedef std::list< shared_ptr<EventDataItem> > DataItemList; typedef std::list<boost::signals::connection> ConnectionList; class MyClass { void OnStart() { DataItemList dilItems; ConnectionList clConns; DataItemList::iterator iterDataItems; for(iterDataItems = dilItems.begin(); iterDataItems != dilItems.end(); iterDataItems++) { // Create Connections from Triggers clConns.push_back((*iterDataItems)->OnTrigger.connect( bind(&MyClass::OnEventTrigger, this))); } } void OnEventTrigger() { // ... Do stuff on Trigger... } } I'd like to change MyClass::OnStart to use std::transform to achieve the same thing: void MyClass::OnStart() { DataItemList dilItems; ConnectionList clConns; // Resize connection list to match number of data items clConns.resize(dilItems.size()); // Build connection list from Items // note: errors on the placeholder _1->OnTrigger std::transform(dilItems.begin(), dilItems.end(), clConns.begin(), bind(&EventDataItemSignal::connect, _1->OnTrigger, bind(&MyClass::Stuff, this))); } However, my hiccup is _1-OnTrigger. How can I reference OnTrigger from placeholder _1?

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  • Why is creating a ring buffer shared by different processes so hard (in C++), what I am doing wrong?

    - by recipriversexclusion
    I am being especially dense about this but it seems I'm missing an important, basic point or something, since what I want to do should be common: I need to create a fixed-size ring buffer object from a manager process (Process M). This object has write() and read() methods to write/read from the buffer. The read/write methods will be called by independent processes (Process R and W) I have implemented the buffer, SharedBuffer<T&>, it allocates buffer slots in SHM using boost::interprocess and works perfectly within a single process. I have read the answers to this question and that one on SO, as well as asked my own, but I'm still in the dark about how to have different processes access methods from a common object. The Boost doc has an example of creating a vector in SHM, which is very similar to what I want, but I want to instantiate my own class. My current options are: Use placement new, as suggested by Charles B. to my question; however, he cautions that it's not a good idea to put non-POD objects in SHM. But my class needs the read/write methods, how can I handle those? Add an allocator to my class definition, e.g. have SharedBuffer<T&, Alloc> and proceed similarly to the vector example given in boost. This sounds really complicated. Change SharedBuffer to a POD class, i.e. get rid of all the methods. But then how to synchronize reading and writing between processes? What am I missing? Fixed-length ring buffers are very common, so either this problem has a solution or else I'm doing something wrong.

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  • Immutable classes in C++

    - by ereOn
    Hi, In one of my projects, I have some classes that represent entities that cannot change once created, aka. immutable classes. Example : A class RSAKey that represent a RSA key which only has const methods. There is no point changing the existing instance: if you need another one, you just create one. My objects sometimes are heavy and I enforced the use of smart pointers to avoid copy. So far, I have the following pattern for my classes: class RSAKey : public boost::noncopyable, public boost::enable_shared_from_this<RSAKey> { public: /** * \brief Some factory. * \param member A member value. * \return An instance. */ static boost::shared_ptr<const RSAKey> createFromMember(int member); /** * \brief Get a member. * \return The member. */ int getMember() const; private: /** * \brief Constructor. * \param member A member. */ RSAKey(int member); /** * \brief Member. */ const int m_member; }; So you can only get a pointer (well, a smart pointer) to a const RSAKey. To me, it makes sense, because having a non-const reference to the instance is useless (it only has const methods). Do you guys see any issue regarding this pattern ? Are immutable classes something common in C++ or did I just created a monster ? Thank you for your advices !

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  • Macro to improve callback registration readability

    - by Warren Seine
    I'm trying to write a macro to make a specific usage of callbacks in C++ easier. All my callbacks are member functions and will take this as first argument and a second one whose type inherits from a common base class. The usual way to go is: register_callback(boost::bind(&my_class::member_function, this, _1)); I'd love to write: register_callback(HANDLER(member_function)); Note that it will always be used within the same class. Even if typeof is considered as a bad practice, it sounds like a pretty solution to the lack of __class__ macro to get the current class name. The following code works: typedef typeof(*this) CLASS; boost::bind(& CLASS :: member_function, this, _1)(my_argument); but I can't use this code in a macro which will be given as argument to register_callback. I've tried: #define HANDLER(FUN) \ boost::bind(& typeof(*this) :: member_function, this, _1); which doesn't work for reasons I don't understand. Quoting GCC documentation: A typeof-construct can be used anywhere a typedef name could be used. My compiler is GCC 4.4, and even if I'd prefer something standard, GCC-specific solutions are accepted.

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  • Is there a way to increase the efficiency of shared_ptr by storing the reference count inside the co

    - by BillyONeal
    Hello everyone :) This is becoming a common pattern in my code, for when I need to manage an object that needs to be noncopyable because either A. it is "heavy" or B. it is an operating system resource, such as a critical section: class Resource; class Implementation : public boost::noncopyable { friend class Resource; HANDLE someData; Implementation(HANDLE input) : someData(input) {}; void SomeMethodThatActsOnHandle() { //Do stuff }; public: ~Implementation() { FreeHandle(someData) }; }; class Resource { boost::shared_ptr<Implementation> impl; public: Resource(int argA) explicit { HANDLE handle = SomeLegacyCApiThatMakesSomething(argA); if (handle == INVALID_HANDLE_VALUE) throw SomeTypeOfException(); impl.reset(new Implementation(handle)); }; void SomeMethodThatActsOnTheResource() { impl->SomeMethodThatActsOnTheHandle(); }; }; This way, shared_ptr takes care of the reference counting headaches, allowing Resource to be copyable, even though the underlying handle should only be closed once all references to it are destroyed. However, it seems like we could save the overhead of allocating shared_ptr's reference counts and such separately if we could move that data inside Implementation somehow, like boost's intrusive containers do. If this is making the premature optimization hackles nag some people, I actually agree that I don't need this for my current project. But I'm curious if it is possible.

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  • C++ socket protocol design issue (ring inclusion)

    - by Martin Lauridsen
    So I have these two classes, mpqs_client and client_protocol. The mpqs_client class handles a Boost socket connection to a server (sending and receiving messages with some specific format. Upon receiving a message, it calls a static method, parse_message(..), in the class client_protocol, and this method should analyse the message received and perform some corresponding action. Given some specific input, the parse_message method needs to send some data back to the server. As mentioned, this happens through the class mpqs_client. So I could, from mpqs_client, pass "this" to parse_message(..) in client_protocol. However, this leads to a two-way association relationship between the two classes. Something which I reckon is not desireable. Also, to implement this, I would need to include the other in each one, and this gives me a terrible pain. I am thinking this is more of a design issue. What is the best solution here? Code is posted below. Class mpqs_client: #include "mpqs_client.h" mpqs_client::mpqs_client(boost::asio::io_service& io_service, tcp::resolver::iterator endpoint_iterator) : io_service_(io_service), socket_(io_service) { ... } ... void mpqs_client::write(const network_message& msg) { io_service_.post(boost::bind(&mpqs_client::do_write, this, msg)); } Class client_protocol: #include "../network_message.hpp" #include "../protocol_consts.h" class client_protocol { public: static void parse_message(network_message& msg, mpqs_sieve **instance_, mpqs_client &client_) { ... switch (type) { case MPQS_DATA: ... break; case POLYNOMIAL_DATA: ... break; default: break; } }

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  • How to implement a multi-threaded asynchronous operation?

    - by drowneath
    Here's how my current approach looks like: // Somewhere in a UI class // Called when a button called "Start" clicked MyWindow::OnStartClicked(Event &sender) { _thread = new boost::thread(boost::bind(&MyWindow::WorkToDo, this)); } MyWindow::WorkToDo() { for(int i = 1; i < 10000000; i++) { int percentage = (int)((float)i / 100000000.f); _progressBar->SetValue(percentage); _statusText->SetText("Working... %d%%", percentage); printf("Pretend to do something useful...\n"); } } // Called on every frame MyWindow::OnUpdate() { if(_thread != 0 && _thread->timed_join(boost::posix_time::seconds(0)) { _progressBar->SetValue(100); _statusText->SetText("Completed!"); delete _thread; _thread = 0; } } But I'm afraid this is far from safe since I keep getting unhandled exception at the end of the program execution. I basically want to separate a heavy task into another thread without blocking the GUI part.

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  • How to synchronize access to many objects

    - by vividos
    I have a thread pool with some threads (e.g. as many as number of cores) that work on many objects, say thousands of objects. Normally I would give each object a mutex to protect access to its internals, lock it when I'm doing work, then release it. When two threads would try to access the same object, one of the threads has to wait. Now I want to save some resources and be scalable, as there may be thousands of objects, and still only a hand full of threads. I'm thinking about a class design where the thread has some sort of mutex or lock object, and assigns the lock to the object when the object should be accessed. This would save resources, as I only have as much lock objects as I have threads. Now comes the programming part, where I want to transfer this design into code, but don't know quite where to start. I'm programming in C++ and want to use Boost classes where possible, but self written classes that handle these special requirements are ok. How would I implement this? My first idea was to have a boost::mutex object per thread, and each object has a boost::shared_ptr that initially is unset (or NULL). Now when I want to access the object, I lock it by creating a scoped_lock object and assign it to the shared_ptr. When the shared_ptr is already set, I wait on the present lock. This idea sounds like a heap full of race conditions, so I sort of abandoned it. Is there another way to accomplish this design? A completely different way?

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  • Speed boost to adjacency matrix

    - by samoz
    I currently have an algorithm that operates on an adjacency matrix of size n by m. In my algorithm, I need to zero out entire rows or columns at a time. My implementation is currently O(m) or O(n) depending on if it's a column or row. Is there any way to zero out a column or row in O(1) time?

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  • Cython Speed Boost vs. Usability

    - by zubin71
    I just came across Cython, while I was looking out for ways to optimize Python code. I read various posts on stackoverflow, the python wiki and read the article "General Rules for Optimization". Cython is something which grasps my interest the most; instead of writing C-code for yourself, you can choose to have other datatypes in your python code itself. Here is a silly test i tried, #!/usr/bin/python # test.pyx def test(value): for i in xrange(value): i**2 if(i==1000000): print i test(10000001) $ time python test.pyx real 0m16.774s user 0m16.745s sys 0m0.024s $ time cython test.pyx real 0m0.513s user 0m0.196s sys 0m0.052s Now, honestly, i`m dumbfounded. The code which I have used here is pure python code, and all I have changed is the interpreter. In this case, if cython is this good, then why do people still use the traditional Python interpretor? Are there any reliability issues for Cython?

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  • Boost Shared Pointer: Simultaneous Read Access Across Multiple Threads

    - by Nikhil
    I have a thread A which allocates memory and assigns it to a shared pointer. Then this thread spawns 3 other threads X, Y and Z and passes a copy of the shared pointer to each. When X, Y and Z go out of scope, the memory is freed. But is there a possibility that 2 threads X, Y go out of scope at the exact same point in time and there is a race condition on reference count so instead of decrementing it by 2, it only gets decremented once. So, now the reference count newer drops to 0, so there is a memory leak. Note that, X, Y and Z are only reading the memory. Not writing or resetting the shared pointer. To cut a long story short, can there be a race condition on the reference count and can that lead to memory leaks?

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  • Splitting Code into Headers/Source files

    - by cam
    I took the following code from the examples page on Asio class tcp_connection : public boost::enable_shared_from_this<tcp_connection> { public: typedef boost::shared_ptr<tcp_connection> pointer; static pointer create(boost::asio::io_service& io_service) { return pointer(new tcp_connection(io_service)); } tcp::socket& socket() { return socket_; } void start() { message_ = make_daytime_string(); boost::asio::async_write(socket_, boost::asio::buffer(message_), boost::bind(&tcp_connection::handle_write, shared_from_this(), boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } private: tcp_connection(boost::asio::io_service& io_service) : socket_(io_service) { } void handle_write(const boost::system::error_code& /*error*/, size_t /*bytes_transferred*/) { } tcp::socket socket_; std::string message_; }; I'm relatively new to C++ (from a C# background), and from what I understand, most people would split this into header and source files (declaration/implementation, respectively). Is there any reason I can't just leave it in the header file if I'm going to use it across many source files? If so, are there any tools that will automatically convert it to declaration/implementation for me? Can someone show me what this would look like split into header/source file for an example (or just part of it, anyway)? I get confused around weird stuff like thistypedef boost::shared_ptr<tcp_connection> pointer; Do I include this in the header or the source? Same with tcp::socket& socket() I've read many tutorials, but this has always been something that has confused me about C++.

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