Search Results

Search found 44910 results on 1797 pages for 'breadth first traversal'.

Page 274/1797 | < Previous Page | 270 271 272 273 274 275 276 277 278 279 280 281  | Next Page >

  • Catch Multiple Custom Exceptions? - C++

    - by Alex
    Hi all, I'm a student in my first C++ programming class, and I'm working on a project where we have to create multiple custom exception classes, and then in one of our event handlers, use a try/catch block to handle them appropriately. My question is: How do I catch my multiple custom exceptions in my try/catch block? GetMessage() is a custom method in my exception classes that returns the exception explanation as a std::string. Below I've included all the relevant code from my project. Thanks for your help! try/catch block // This is in one of my event handlers, newEnd is a wxTextCtrl try { first.ValidateData(); newEndT = first.ComputeEndTime(); *newEnd << newEndT; } catch (// don't know what do to here) { wxMessageBox(_(e.GetMessage()), _("Something Went Wrong!"), wxOK | wxICON_INFORMATION, this);; } ValidateData() Method void Time::ValidateData() { int startHours, startMins, endHours, endMins; startHours = startTime / MINUTES_TO_HOURS; startMins = startTime % MINUTES_TO_HOURS; endHours = endTime / MINUTES_TO_HOURS; endMins = endTime % MINUTES_TO_HOURS; if (!(startHours <= HOURS_MAX && startHours >= HOURS_MIN)) throw new HourOutOfRangeException("Beginning Time Hour Out of Range!"); if (!(endHours <= HOURS_MAX && endHours >= HOURS_MIN)) throw new HourOutOfRangeException("Ending Time Hour Out of Range!"); if (!(startMins <= MINUTE_MAX && startMins >= MINUTE_MIN)) throw new MinuteOutOfRangeException("Starting Time Minute Out of Range!"); if (!(endMins <= MINUTE_MAX && endMins >= MINUTE_MIN)) throw new MinuteOutOfRangeException("Ending Time Minute Out of Range!"); if(!(timeDifference <= P_MAX && timeDifference >= P_MIN)) throw new PercentageOutOfRangeException("Percentage Change Out of Range!"); if (!(startTime < endTime)) throw new StartEndException("Start Time Cannot Be Less Than End Time!"); } Just one of my custom exception classes, the others have the same structure as this one class HourOutOfRangeException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type HourOutOfRangeException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~HourOutOfRangeException() {} private: string message; };

    Read the article

  • Track/Display Array Index As Part Of Cout (C++)

    - by John Smith
    Hi, I have a command line C++ program that lets you enter basic information about a person (ID number, name, age, etc.) and I want to output to a console in the following manner: ------------------------------------------------------------------- Index ID # First Name Last Name Age ------------------------------------------------------------------- 0 1234 John Smith 25 The person objects are stored in an array of Persons and I've overload the ostream (<<) operator to print out all of the fields like you see. The dashed lines and header come from a displayHdg() function. Anyhow, I have not been able to figure out how to get the proper index value for the array. Ideally, I'd like to generate the indices for each line, but all my attempts have failed. The array is looped through and each object printed in the main() function, and the ostream is overloaded in a person class, so I tried to use global variables as well as static variables, and all of those produce incorrect numbering (i.e. show 0, 1 the first time (for 2 objects), then change to 1, 2 on the next display). Any ideas?

    Read the article

  • c++ queue template

    - by Dalton Conley
    ALright, pardon my messy code please. Below is my queue class. #include <iostream> using namespace std; #ifndef QUEUE #define QUEUE /*---------------------------------------------------------------------------- Student Class # Methods # Student() // default constructor Student(string, int) // constructor display() // out puts a student # Data Members # Name // string name Id // int id ----------------------------------------------------------------------------*/ class Student { public: Student() { } Student(string iname, int iid) { name = iname; id = iid; } void display(ostream &out) const { out << "Student Name: " << name << "\tStudent Id: " << id << "\tAddress: " << this << endl; } private: string name; int id; }; // define a typedef of a pointer to a student. typedef Student * StudentPointer; template <typename T> class Queue { public: /*------------------------------------------------------------------------ Queue Default Constructor Preconditions: none Postconditions: assigns default values for front and back to 0 description: constructs a default empty Queue. ------------------------------------------------------------------------*/ Queue() : myFront(0), myBack(0) {} /*------------------------------------------------------------------------ Copy Constructor Preconditions: requres a reference to a value for which you are copying Postconditions: assigns a copy to the parent Queue. description: Copys a queue and assigns it to the parent Queue. ------------------------------------------------------------------------*/ Queue(const T & q) { myFront = myBack = 0; if(!q.empty()) { // copy the first node myFront = myBack = new Node(q.front()); NodePointer qPtr = q.myFront->next; while(qPtr != NULL) { myBack->next = new Node(qPtr->data); myBack = myBack->next; qPtr = qPtr->next; } } } /*------------------------------------------------------------------------ Destructor Preconditions: none Postconditions: deallocates the dynamic memory for the Queue description: deletes the memory stored for a Queue. ------------------------------------------------------------------------*/ ~Queue() { NodePointer prev = myFront, ptr; while(prev != NULL) { ptr = prev->next; delete prev; prev = ptr; } } /*------------------------------------------------------------------------ Empty() Preconditions: none Postconditions: returns a boolean value. description: returns true/false based on if the queue is empty or full. ------------------------------------------------------------------------*/ bool empty() const { return (myFront == NULL); } /*------------------------------------------------------------------------ Enqueue Preconditions: requires a constant reference Postconditions: allocates memory and appends a value at the end of a queue description: ------------------------------------------------------------------------*/ void enqueue(const T & value) { NodePointer newNodePtr = new Node(value); if(empty()) { myFront = myBack = newNodePtr; newNodePtr->next = NULL; } else { myBack->next = newNodePtr; myBack = newNodePtr; newNodePtr->next = NULL; } } /*------------------------------------------------------------------------ Display Preconditions: requires a reference of type ostream Postconditions: returns the ostream value (for chaining) description: outputs the contents of a queue. ------------------------------------------------------------------------*/ void display(ostream & out) const { NodePointer ptr; ptr = myFront; while(ptr != NULL) { out << ptr->data << " "; ptr = ptr->next; } out << endl; } /*------------------------------------------------------------------------ Front Preconditions: none Postconditions: returns a value of type T description: returns the first value in the parent Queue. ------------------------------------------------------------------------*/ T front() const { if ( !empty() ) return (myFront->data); else { cerr << "*** Queue is empty -- returning garbage value ***\n"; T * temp = new(T); T garbage = * temp; delete temp; return garbage; } } /*------------------------------------------------------------------------ Dequeue Preconditions: none Postconditions: removes the first value in a queue ------------------------------------------------------------------------*/ void dequeue() { if ( !empty() ) { NodePointer ptr = myFront; myFront = myFront->next; delete ptr; if(myFront == NULL) myBack = NULL; } else { cerr << "*** Queue is empty -- " "can't remove a value ***\n"; exit(1); } } /*------------------------------------------------------------------------ pverloaded = operator Preconditions: requires a constant reference Postconditions: returns a const type T description: this allows assigning of queues to queues ------------------------------------------------------------------------*/ Queue<T> & operator=(const T &q) { // make sure we arent reassigning ourself // e.g. thisQueue = thisQueue. if(this != &q) { this->~Queue(); if(q.empty()) { myFront = myBack = NULL; } else { myFront = myBack = new Node(q.front()); NodePointer qPtr = q.myFront->next; while(qPtr != NULL) { myBack->next = new Node(qPtr->data); myBack = myBack->next; qPtr = qPtr->next; } } } return *this; } private: class Node { public: T data; Node * next; Node(T value, Node * first = 0) : data(value), next(first) {} }; typedef Node * NodePointer; NodePointer myFront, myBack, queueSize; }; /*------------------------------------------------------------------------ join Preconditions: requires 2 queue values Postconditions: appends queue2 to the end of queue1 description: this function joins 2 queues into 1. ------------------------------------------------------------------------*/ template <typename T> Queue<T> join(Queue<T> q1, Queue<T> q2) { Queue<T> q1Copy(q1), q2Copy(q2); Queue<T> jQueue; while(!q1Copy.empty()) { jQueue.enqueue(q1Copy.front()); q1Copy.dequeue(); } while(!q2Copy.empty()) { jQueue.enqueue(q2Copy.front()); q2Copy.dequeue(); } cout << jQueue << endl; return jQueue; } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a Queue of type T Postconditions: returns the ostream (for chaining) description: this function is overloaded for outputing a queue with << ----------------------------------------------------------------------------*/ template <typename T> ostream & operator<<(ostream &out, Queue<T> &s) { s.display(out); return out; } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a reference of type Student Postconditions: none description: this function is overloaded for outputing an object of type Student. ----------------------------------------------------------------------------*/ ostream & operator<<(ostream &out, Student &s) { s.display(out); } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a reference of a pointer to a Student object. Postconditions: none description: this function is overloaded for outputing pointers to Students ----------------------------------------------------------------------------*/ ostream & operator<<(ostream &out, StudentPointer &s) { s->display(out); } #endif Now I'm having some issues with it. For one, when I add 0 to a queue and then I output the queue like so.. Queue<double> qdub; qdub.enqueue(0); cout << qdub << endl; That works, it will output 0. But for example, if I modify that queue in any way.. like.. assign it to a different queue.. Queue<double> qdub1; Queue<double> qdub2; qdub1.enqueue(0; qdub2 = qdub1; cout << qdub2 << endl; It will give me weird values for 0 like.. 7.86914e-316. Help on this would be much appreciated!

    Read the article

  • Finding N contiguous zero bits in an integer to the left of the MSB position of another integer

    - by James Morris
    The problem is: given an integer val1 find the position of the highest bit set (Most Significant Bit) then, given a second integer val2 find a contiguous region of unset bits, with the minimum number of zero bits given by width to the left of the position (ie, in the higher bits). Here is the C code for my solution: typedef unsigned int t; unsigned const t_bits = sizeof(t) * CHAR_BIT; _Bool test_fit_within_left_of_msb( unsigned width, t val1, t val2, unsigned* offset_result) { unsigned offbit = 0; unsigned msb = 0; t mask; t b; while(val1 >>= 1) ++msb; while(offbit + width < t_bits - msb) { mask = (((t)1 << width) - 1) << (t_bits - width - offbit); b = val2 & mask; if (!b) { *offset_result = offbit; return true; } if (offbit++) /* this conditional bothers me! */ b <<= offbit - 1; while(b <<= 1) offbit++; } return false; } Aside from faster ways of finding the MSB of the first integer, the commented test for a zero offbit seems a bit extraneous, but necessary to skip the highest bit of type t if it is set. I have also implemented similar algorithms but working to the right of the MSB of the first number, so they don't require this seemingly extra condition. How can I get rid of this extra condition, or even, are there far more optimal solutions? Edit: Some background not strictly required. The offset result is a count of bits from the high bit, not from the low bit as maybe expected. This will be part of a wider algorithm which scans a 2D array for a 2D area of zero bits. Here, for testing, the algorithm has been simplified. val1 represents the first integer which does not have all bits set found in a row of the 2D array. From this the 2D version would scan down which is what val2 represents. Here's some output showing success and failure: t_bits:32 t_high: 10000000000000000000000000000000 ( 2147483648 ) --------- ----------------------------------- *** fit within left of msb test *** ----------------------------------- val1: 00000000000000000000000010000000 ( 128 ) val2: 01000001000100000000100100001001 ( 1091569929 ) msb: 7 offbit:0 + width: 8 = 8 mask: 11111111000000000000000000000000 ( 4278190080 ) b: 01000001000000000000000000000000 ( 1090519040 ) offbit:8 + width: 8 = 16 mask: 00000000111111110000000000000000 ( 16711680 ) b: 00000000000100000000000000000000 ( 1048576 ) offbit:12 + width: 8 = 20 mask: 00000000000011111111000000000000 ( 1044480 ) b: 00000000000000000000000000000000 ( 0 ) offbit:12 iters:10 ***** found room for width:8 at offset: 12 ***** ----------------------------------- *** fit within left of msb test *** ----------------------------------- val1: 00000000000000000000000001000000 ( 64 ) val2: 00010000000000001000010001000001 ( 268469313 ) msb: 6 offbit:0 + width: 13 = 13 mask: 11111111111110000000000000000000 ( 4294443008 ) b: 00010000000000000000000000000000 ( 268435456 ) offbit:4 + width: 13 = 17 mask: 00001111111111111000000000000000 ( 268402688 ) b: 00000000000000001000000000000000 ( 32768 ) ***** mask: 00001111111111111000000000000000 ( 268402688 ) offbit:17 iters:15 ***** no room found for width:13 ***** (iters is the count of iterations of the inner while loop)

    Read the article

  • Factor Clojure code setting many different fields in a Java object

    - by chris
    How do I factor code setting many different fields in a Java object? I would like to factor (set! (. employee name) "Chris") (set! (. employee age) 100) (set! (. employee salary) 5000) to (doseq [field '((name "Chris") (age 100) (salary 5000))] (set! (. employee (first field)) (second field))) However this won't work because the period is a macro, and tries to evaluate (first field) literally. By the way, I understand that setting fields is not good practice. I need to inter-operate with legacy code.

    Read the article

  • Summarising (permanently) data in a SQL table

    - by Cylindric
    Geetings, Stackers. I have a huge number of data-points in a SQL table, and I want to summarise them in a way reminiscent of RRD. Assuming a table such as ID | ENTITY_ID | SCORE_DATE | SCORE | SOME_OTHER_DATA ----+-----------+------------+-------+----------------- 1 | A00000001 | 01/01/2010 | 100 | some data 2 | A00000002 | 01/01/2010 | 105 | more data 3 | A00000003 | 01/01/2010 | 104 | various text ... | ......... | .......... | ..... | ... ... | A00009999 | 01/01/2010 | 101 | ... | A00000001 | 02/01/2010 | 104 | ... | A00000002 | 02/01/2010 | 119 | ... | A00000003 | 02/01/2010 | 119 | ... | ......... | .......... | ..... | ... | A00009999 | 02/01/2010 | 101 | arbitrary data ... | ......... | .......... | ..... | ... ... | A00000001 | 01/02/2010 | 104 | ... | A00000002 | 01/02/2010 | 119 | ... | A00000003 | 01/01/2010 | 119 | I want to end up with one record per entity, per month: ID | ENTITY_ID | SCORE_DATE | SCORE | ----+-----------+------------+-------+ ... | A00000001 | 01/01/2010 | 100 | ... | A00000002 | 01/01/2010 | 105 | ... | A00000003 | 01/01/2010 | 104 | ... | A00000001 | 01/02/2010 | 100 | ... | A00000002 | 01/02/2010 | 105 | ... | A00000003 | 01/02/2010 | 104 | (I Don't care about the SOME_OTHER_DATA - I'll pick something - either the first or last record probably.) What's an easy way of doing this on a regular basis, so that anything in the last calendar month is summarised in this way? At the moment my plan is kind of: For each EntityID For each month Find average score for all records in given month Update first record with results of previous step Delete all records that aren't the first I can't think of a neat way of doing it though, that doesn't involve lots of updates and iteration. This can either be done in a SQL Stored Procedure, or it can be incorporated into the .Net app that's generating this data, so the solution doesn't really need to be "one big SQL script", but can be :) (SQL-2005)

    Read the article

  • Blackberry - Custom size EditField

    - by Eric
    I am trying to put together a dialog that should look like this: Fill in the below fields ___________ likes ________________ where the "_" lines are the EditFields. I am sticking all the fields in a HorizontalFieldManager, which I add to the dialog. Unfortunately, the first EditField consumes all the space on the first line. I have tried to override the getPreferredWidth() method of the EditField by creating my own class extending BasicEditField, but have had no success. Surely there must be a simple way to force a certain size for an edit field. What am I missing?

    Read the article

  • Setting Grouping in UITableView under UINavigationController

    - by climbon
    In my UINavigationController app, my first view is a UITableView. I can't seem to find a way to set the property of this UITableView to 'grouped'. Since UITableView is dynamically generated I don't have the luxury of Interface Builder. Searched forums here and googled other places and closest I saw was to override either initWithStyle or initWithCoder as follows. (id)initWithStyle:(UITableViewStyle)style { if (self = [super initWithStyle:UITableViewStyleGrouped]) { } return self; } However this above function never gets called. when I overrided initWithCoder I could see it worked and I was able to change UITableView contents to grouped. But then title automatically became 'Root View Controller' and none of the cells were active anymore although they got grouped fine. That is while they looked active but if you click on them, those cells won't do anything. But I have seen apps which have their very first view being UITableView is grouped. So there must be a way to do it but I don't know how.

    Read the article

  • Android pluginable application

    - by Alxandr
    I've been trying to create an android-application the last couple of weeks, and mostly everything has worked out great, but there is one thing that I was wondering about, and that is pluginability trough the use of intents. What I'm trying to create is basically a comic-reader. As of the version I use now, I open the application and get a list of commics that are my favourites, then I enter one to get a detailed view, and finally I enter a page. This is managed trough 3 activities. List, Details and Page. However, as of now the application can only read comics of one source (a specialiced xml-feed comming from my server), and I was hoping to be able to expand this a litle (also, the page-activity and some other stuff needs to be cleaned up in, so I'm thinking about remaking from scratch, and just take the first go as a learning-round). And I came up with an idea which I think sounds great, but I don't know if it's possible, but this is what I'm thinking about: The user enters the application and get an (first time empty) list of comics. The user hits a button to find comics, this launces an intent that says something like "find comic" or something like that. This should cause the system to display all matching activities. This would make it possible to provide different comic-providers trough different applications. Another activity kicks in and might displays some options to the user (for instance a file-browser), or might not (in the example of an xml-feed, which should just load). The list is returned to the first activity and displayed to the user. The second (find) activity is closed. The user picks a comic from the list. This should open some details-activity. The details-activity should receive a key which corresponds to the comic selected. This should be unique amongst the comic-providers. The details-view should get it's data trough some cind of content-provider, or an activity (whichever is most suited, if one of them is). The user can select a page. This should be the same routine as step 5. My question is, is this possible in the android system, and if it is, is it a bad idea? And also, is there any better way to achieve more or less the same thing?

    Read the article

  • How to control a subthread process in python?

    - by SpawnCxy
    Code first: '''this is main structure of my program''' from twisted.web import http from twisted.protocols import basic import threading threadstop = False #thread trigger,to be done class MyThread(threading.Thread): def __init__(self): threading.Thread.__init__(self) self.start() def run(self): while True: if threadstop: return dosomething() '''def some function''' if __name__ == '__main__': from twisted.internet import reactor t = MyThread() reactor.listenTCP(serverport,myHttpFactory()) reactor.run() As my first multithread program,I feel happy that it works as expected.But now I find I cannot control it.If I run it on front,Control+C can only stop the main process,and I can still find it in processlist;if I run it in background,I have to use kill -9 pid to stop it.And I wonder if there's a way to control the subthread process by a trigger variale,or a better way to stop the whole process other than kill -9.Thanks.

    Read the article

  • JQgrid - escape ':' in searchoptions (value part)

    - by bsreekanth
    Hello, How to set the values for filter is explained here link text. I have two requirements. 1. the default value needs to be empty. I expect, if defaultValue is not set, the filter is empty, but that is not happening in my case. The first value is 2. How to escape ':' in my value. The character ':' and ';' are used to seperate the index and values. But, in my value string it contains a ':' (eg: searchoptions:{value:"1:'Level: 1'"} , where Level: 1 is my first value). How to escape : in the value part. I tried \ , / etc. thanks.

    Read the article

  • Paging in ActiveRecord

    - by Alex
    Does CastleProject ActiveRecord support paging? I need to load only data which is now seen on the screen. If I use [HasMany], it will be loaded as a whole either immediately or at the first call (if lazy attribute is true). However I only need something like first 100 records (then maybe 100 next records). Another question is how to load only 100 items. If the collection is too big, memory can reach its limit if we constantly load more and more items.

    Read the article

  • matplotlib: working with range in x-axis

    - by user324333
    Hey Guys, I'm trying to do a basic line graph here, but I can't seem to figure out how to adjust my x axis. And here is the error I get when I try adjusting my range. from pylab import * plot ( range(0,11),[9,4,5,2,3,5,7,12,2,3],'.-',label='sample1' ) plot ( range(0,11),[12,5,33,2,4,5,3,3,22,10],'o-',label='sample2' ) xlabel('x axis') ylabel('y axis') title('my sample graphs') legend(('sample1','sample2')) savefig("sampleg.png",dpi=(640/8)) show() File "C:\Python26\lib\site-packages\matplotlib\axes.py", line 228, in _xy_from_xy raise ValueError("x and y must have same first dimension") ValueError: x and y must have same first dimension I want my range to be a list of strings: ["12/1/2007","12/1/2008", "12/1/2009","12/1/2010"] Any suggestions?

    Read the article

  • C# Enum Flags Comparison

    - by destructo_gold
    Given the following flags, [Flags] public enum Operations { add = 1, subtract = 2, multiply = 4, divide = 8, eval = 16, } How could I implement an IF condition to perform each operation? In my attempt, the first condition is true for add, eval, which is correct. However the first condition is also true for subtract, eval, which is incorrect. public double Evaluate(double input) { if ((operation & (Operations.add & Operations.eval)) == (Operations.add & Operations.eval)) currentResult += input; else if ((operation & (Operations.subtract & Operations.eval)) == (Operations.subtract & Operations.eval)) currentResult -= input; else currentResult = input; operation = null; return currentResult; } I cannot see what the problem is.

    Read the article

  • Java multiline string

    - by skiphoppy
    Coming from Perl, I sure am missing the "here-document" means of creating a multi-line string in source code: $string = <<"EOF" # create a three line string text text text EOF In Java I have to have cumbersome quotes and plus signs on every line as I concatenate my multiline string from scratch. What are some better alternatives? Define my string in a properties file? Edit: Two answers say StringBuilder.append() is preferable to the plus notation. Could anyone elaborate as to why they think so? It doesn't look more preferable to me at all. I'm looking for away around the fact that multiline strings are not a first-class language construct, which means I definitely don't want to replace a first-class language construct (string concatenation with plus) with method calls. Edit: To clarify my question further, I'm not concerned about performance at all. I'm concerned about maintainability and design issues.

    Read the article

  • How to direct people to fill out a form

    - by Solmead
    What is the best way to get people to fill out a form correctly? For instance I originally had a "Name" field on a form and I want 1 person per form. People filled it out like this: "Mark & Becky Newsman". So I broke it into 2 fields, "First Name" and "Last Name", And people are still filling it out wrong, like "First Name" = "Mark & Becky", "Last Name" = "Newsman". Are there any recommendations on how better to get people to understand that only one person's name should go there? I currently have it on two lines, would it work better to put both fields on one line? If this is on the wrong site go ahead and move it to the correct site.

    Read the article

  • how to run foreach loop with ternary condition

    - by I Like PHP
    i have two foreach loop to display some data, but i want to use a single foreach on basis of database result. means if there is any row returns from database then forach($first as $fk=>$fv) should execute otherwise foreach($other as $ok) should execute. i m unsing below ternary operator which gives parse error $n=$db->numRows($taskData); // databsse results <?php ($n) ? foreach ($first as $fk=>$fv) : foreach ($other as $ok) { ?> <table><tr><td>......some data...</td></tr></table> <?php } ?> please suggest me how to handle such condition via ternary operator or any other idea. Thanks

    Read the article

  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

    Read the article

  • The "correct" way to define an exception in Python without PyLint complaining

    - by Evgeny
    I'm trying to define my own (very simple) exception class in Python 2.6, but no matter how I do it I get some warning. First, the simplest way: class MyException(Exception): pass This works, but prints out a warning at runtime: DeprecationWarning: BaseException.message has been deprecated as of Python 2.6 OK, so that's not the way. I then tried: class MyException(Exception): def __init__(self, message): self.message = message This also works, but PyLint reports a warning: W0231: MyException.__init__: __init__ method from base class 'Exception' is not called. So I tried calling it: class MyException(Exception): def __init__(self, message): super(Exception, self).__init__(message) self.message = message This works, too! But now PyLint reports an error: E1003: MyException.__init__: Bad first argument 'Exception' given to super class How the hell do I do such a simple thing without any warnings?

    Read the article

  • Regex and Pattern Matching in Scala

    - by Bruce Ferguson
    I am not strong in regex, and pretty new to Scala. I would like to be able to find a match between the first letter of a word, and one of the letters in a group such as "ABC". In pseudocode, this might look something like: case Process(word) => word.firstLetter match { case([a-c][A-C]) => case _ => } } but I don't know how to grab the first letter in Scala instead of Java, how to express the regular expression properly, nor if it's possible to do this within a case class. Any suggestions? Thanks in advance. Bruce

    Read the article

  • iphone simulator crashes when it tries to access user location

    - by kevin Mendoza
    for some reason my code causes my program to crash. does anyone know why or how to fix it? NSLog(@"here"); CLLocation *location = [locationManager location]; [mapView removeAnnotations:mapView.annotations]; NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; CLLocationCoordinate2D workingCoordinate = [location coordinate]; NSLog(@" this is %@", workingCoordinate.latitude); it makes it to the first NSLog, but somewhere between the first and second it crashes. My guess is that it has to do with the CLLocation *location line.

    Read the article

  • Provide me with recources on Greibach & Chomsky Normal Form

    - by kristian Roger
    Hi, first please (bare with me)... :-( Im having a course at University ( Theory of Computation ) at first it was easy and simple BUT then we reach the context free grammer specialy the part where we should convert a grammer to Normal forms (Greibach & Chomsky) the thing that I couldnt understand so as usual I went to google and start searching for tutorials or videos I found many(tutorials not videos) but the problem that in tutorials they always explain things as if Im an expert or aware of every thing ... so can anyone please provide me with docs or links where they explaine the methods step by step ... (Please dont tell me to go back to my instructor because if he is useful I wont be asking your help ) thanx in advance

    Read the article

  • Using IOperationBehavior to supply a WCF parameter

    - by Chris Kemp
    This is my first step into the world of stackoverflow, so apologies if I cock anything up. I'm trying to create a WCF Operation which has a parameter that is not exposed to the outside world, but is instead automatically passed into the function. So the world sees this: int Add(int a, int b) But it is implemented as: int Add(object context, int a, int b) Then, the context gets supplied by the system at run-time. The example I'm working with is completely artificial, but mimics something that I'm looking into in a real-world scenario. I'm able to get close, but not quite the whole way there. First off, I created a simple method and wrote an application to confirm it works. It does. It returns a + b and writes the context as a string to my debug. Yay. [OperationContract] int Add(object context, int a, int b); I then wrote the following code: public class SupplyContextAttribute : Attribute, IOperationBehavior { public void Validate(OperationDescription operationDescription) { if (!operationDescription.Messages.Any(m => m.Body.Parts.First().Name == "context")) throw new FaultException("Parameter 'context' is missing."); } public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation) { dispatchOperation.Invoker = new SupplyContextInvoker(dispatchOperation.Invoker); } public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation) { } public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters) { // Remove the 'context' parameter from the inbound message operationDescription.Messages[0].Body.Parts.RemoveAt(0); } } public class SupplyContextInvoker : IOperationInvoker { readonly IOperationInvoker _invoker; public SupplyContextInvoker(IOperationInvoker invoker) { _invoker = invoker; } public object[] AllocateInputs() { return _invoker.AllocateInputs().Skip(1).ToArray(); } private object[] IntroduceContext(object[] inputs) { return new[] { "MyContext" }.Concat(inputs).ToArray(); } public object Invoke(object instance, object[] inputs, out object[] outputs) { return _invoker.Invoke(instance, IntroduceContext(inputs), out outputs); } public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state) { return _invoker.InvokeBegin(instance, IntroduceContext(inputs), callback, state); } public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result) { return _invoker.InvokeEnd(instance, out outputs, result); } public bool IsSynchronous { get { return _invoker.IsSynchronous; } } } And my WCF operation now looks like this: [OperationContract, SupplyContext] int Amend(object context, int a, int b); My updated references no longer show the 'context' parameter, which is exactly what I want. The trouble is that whenver I run the code, it gets past the AllocateInputs and then throws an Index was outside the bounds of the Array. error somewhere in the WCF guts. I've tried other things, and I find that I can successfully change the type of the parameter and rename it and have my code work. But the moment I remove the parameter it falls over. Can anyone give me some idea of how to get this to work (or if it can be done at all).

    Read the article

  • Matching of tuples

    - by Jack
    From what I understood I can use pattern-matching in a match ... with expression with tuples of values, so something like match b with ("<", val) -> if v < val then true else false | ("<=", val) -> if v <= val then true else false should be correct but it gives me a syntax error as if the parenthesis couldn't be used: File "ocaml.ml", line 41, characters 14-17: Error: Syntax error: ')' expected File "ocaml.ml", line 41, characters 8-9: Error: This '(' might be unmatched referring on first match clause.. Apart from that, can I avoid matching strings and applying comparisons using a sort of eval of the string? Or using directly the comparison operator as the first element of the tuple?

    Read the article

  • Table Disobeys W3C Box Model, Ie8 Ignores Fixed Table Width !

    - by Axel Myers
    Hi, I'm having hard time with tables and column widths. Update: I'm using XHTML Strict 1.0. The page is: http://www.pro-turk.net/try The first problem I have is, I have a column with a fixed width of 100px and 4px padding, but it disobeys my padding depending on the value. The column width (as the distance between two borders according to W3C Box Model) is 156 px even if padding is 0 or 4. Only the position of the text changes. According to W3C Box Model ( available at www.pro-turk.net/box_model.png ), borders and paddings aren't included in WIDTH attribute, so why does it render wrongly ? The second problem is, when you look the page I gave with IE8, the first cell in the second row has 150px fixed width, but ie shows it about 50% of the total table width regardless of what i say.

    Read the article

< Previous Page | 270 271 272 273 274 275 276 277 278 279 280 281  | Next Page >