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  • Split a map using Groovy

    - by Tihom
    I want to split up a map into an array of maps. For example, if there is a map with 25 key/value pairs. I want an array of maps with no more than 10 elements in each map. How would I do this in groovy? I have a solution which I am not excited about, is there better groovy version: static def splitMap(m, count){ if (!m) return def keys = m.keySet().toList() def result = [] def num = Math.ceil(m?.size() / count) (1..num).each { def min = (it - 1) * count def max = it * count > keys.size() ? keys.size() - 1 : it * count - 1 result[it - 1] = [:] keys[min..max].each {k -> result[it - 1][k] = m[k] } } result } m is the map. Count is the max number of elements within the map.

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  • Why does instanceof seem to work in a static generic function sometimes?

    - by michael
    Greetings. This is my first post in this site. I thought that because of type erasure, one could not expect the following code to compile, and indeed, it did not compile on an earlier version of Eclipse. My understanding was that instanceof was a run-time operator and could not know about the generic type which would be, by run-time, compiled away: public static <E extends Comparable<? super E>> void SampleForQuestion(E e) { if ( !(e instanceof String) ) System.out.println("I am not a String"); else System.out.println("I am a String"); } However, I was surprised to see that one of your threads actually included some code like this in an answer, and my latest Eclipse (Galileo on Windows with JVM 1.6 rev 20) is perfectly happy with it -- and it works, too. (I did notice that someone said it worked on Eclipse but not in another IDE/JDK in that thread, but don't remember the specifics.) Can someone explain why it works, and more importantly, because I have to guide my students, whether it should be expected to work in the future. Thank you. (I hope the code formatting comes through correctly - it looks indented correctly from my perspective and there are no tabs.)

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  • What is the naming convention in Python for variable and function names?

    - by Ray Vega
    Coming from a C# background the naming convention for variables and method names are usually either CamelCase or Pascal Case: // C# example string thisIsMyVariable = "a" public void ThisIsMyMethod() In Python, I have seen the above but I have also seen underscores being used: # python example this_is_my_variable = 'a' def this_is_my_function(): Is there a more preferable, definitive coding style for Python?

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  • Threadsafe way of exposing keySet()

    - by Jake
    This must be a fairly common occurrence where I have a map and wish to thread-safely expose its key set: public MyClass { Map<String,String> map = // ... public final Set<String> keys() { // returns key set } } Now, if my "map" is not thread-safe, this is not safe: public final Set<String> keys() { return map.keySet(); } And neither is: public final Set<String> keys() { return Collections.unmodifiableSet(map.keySet()); } So I need to create a copy, such as: public final Set<String> keys() { return new HashSet(map.keySet()); } However, this doesn't seem safe either because that constructor traverses the elements of the parameter and add()s them. So while this copying is going on, a ConcurrentModificationException can happen. So then: public final Set<String> keys() { synchronized(map) { return new HashSet(map.keySet()); } } seems like the solution. Does this look right?

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  • How to skip integers in C++ taken from a fstream txt file?

    - by Elaina
    I need to create a function that uses a loop. This function will open a text file and then must be able to skip a variable number of leading random integers. The program must be able to handle any number of leading random integers. Example if the opened file reads this on its first line: 100 120 92 82 38 49 102 and the SKIP_NUMBER variable is assigned 3 the number the function would grab is 82. The function must continue to grab the integers every SKIP_NUMBER until it reaches the end of the file. These integers taken from the txt file are then placed into another text file. Please help I'm really lost on how to create this loop! :D Here is my function so far... //Function skips variables and returns needed integer int skipVariable (int SKIP_NUMBER) { return 0; //temporary return } These are my program variables: // initialize function/variables ifstream fin; string IN_FILE_NAME, OUT_FILE_NAME; int SKIP_NUMBER;

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  • Designing small comparable objects

    - by Thomas Ahle
    Intro Consider you have a list of key/value pairs: (0,a) (1,b) (2,c) You have a function, that inserts a new value between two current pairs, and you need to give it a key that keeps the order: (0,a) (0.5,z) (1,b) (2,c) Here the new key was chosen as the average between the average of keys of the bounding pairs. The problem is, that you list may have milions of inserts. If these inserts are all put close to each other, you may end up with keys such to 2^(-1000000), which are not easily storagable in any standard nor special number class. The problem How can you design a system for generating keys that: Gives the correct result (larger/smaller than) when compared to all the rest of the keys. Takes up only O(logn) memory (where n is the number of items in the list). My tries First I tried different number classes. Like fractions and even polynomium, but I could always find examples where the key size would grow linear with the number of inserts. Then I thought about saving pointers to a number of other keys, and saving the lower/greater than relationship, but that would always require at least O(sqrt) memory and time for comparison. Extra info: Ideally the algorithm shouldn't break when pairs are deleted from the list.

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  • How do you return a pointer to a base class with a virtual function?

    - by Nick Sweet
    I have a base class called Element, a derived class called Vector, and I'm trying to redefine two virtual functions from Element in Vector. //element.h template <class T> class Element { public: Element(); virtual Element& plus(const Element&); virtual Element& minus(const Element&); }; and in another file //Vector.h #include "Element.h" template <class T> class Vector: public Element<T> { T x, y, z; public: //constructors Vector(); Vector(const T& x, const T& y = 0, const T& z =0); Vector(const Vector& u); ... //operations Element<T>& plus(const Element<T>& v) const; Element<T>& minus(const Element<T>& v) const; ... }; //sum template <class T> Element<T>& Vector<T>::plus(const Element<T>& v) const { Element<T>* ret = new Vector((x + v.x), (y + v.y), (z + v.z)); return *ret; } //difference template <class T> Element<T>& Vector<T>::minus(const Element<T>& v) const { Vector<T>* ret = new Vector((x - v.x), (y - v.y), (z - v.z)); return *ret; } but I always get error: 'const class Element' has no member named 'getx' So, can I define my virtual functions to take Vector& as an argument instead, or is there a way for me to access the data members of Vector through a pointer to Element? I'm still fairly new to inheritance polymorphism, fyi.

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  • More elegant way to make a C++ member function change different member variables based on template p

    - by Eric Moyer
    Today, I wrote some code that needed to add elements to different container variables depending on the type of a template parameter. I solved it by writing a friend helper class specialized on its own template parameter which had a member variable of the original class. It saved me a few hundred lines of repeating myself without adding much complexity. However, it seemed kludgey. I would like to know if there is a better, more elegant way. The code below is a greatly simplified example illustrating the problem and my solution. It compiles in g++. #include <vector> #include <algorithm> #include <iostream> namespace myNS{ template<class Elt> struct Container{ std::vector<Elt> contents; template<class Iter> void set(Iter begin, Iter end){ contents.erase(contents.begin(), contents.end()); std::copy(begin, end, back_inserter(contents)); } }; struct User; namespace WkNS{ template<class Elt> struct Worker{ User& u; Worker(User& u):u(u){} template<class Iter> void set(Iter begin, Iter end); }; }; struct F{ int x; explicit F(int x):x(x){} }; struct G{ double x; explicit G(double x):x(x){} }; struct User{ Container<F> a; Container<G> b; template<class Elt> void doIt(Elt x, Elt y){ std::vector<Elt> v; v.push_back(x); v.push_back(y); Worker<Elt>(*this).set(v.begin(), v.end()); } }; namespace WkNS{ template<class Elt> template<class Iter> void Worker<Elt>::set(Iter begin, Iter end){ std::cout << "Set a." << std::endl; u.a.set(begin, end); } template<> template<class Iter> void Worker<G>::set(Iter begin, Iter end){ std::cout << "Set b." << std::endl; u.b.set(begin, end); } }; }; int main(){ using myNS::F; using myNS::G; myNS::User u; u.doIt(F(1),F(2)); u.doIt(G(3),G(4)); } User is the class I was writing. Worker is my helper class. I have it in its own namespace because I don't want it causing trouble outside myNS. Container is a container class whose definition I don't want to modify, but is used by User in its instance variables. doIt<F> should modify a. doIt<G> should modify b. F and G are open to limited modification if that would produce a more elegant solution. (As an example of one such modification, in the real application F's constructor takes a dummy parameter to make it look like G's constructor and save me from repeating myself.) In the real code, Worker is a friend of User and member variables are private. To make the example simpler to write, I made everything public. However, a solution that requires things to be public really doesn't answer my question. Given all these caveats, is there a better way to write User::doIt?

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  • Memory efficient collection class

    - by Joe
    I'm building an array of dictionaries (called keys) in my iphone application to hold the section names and row counts for a tableview. the code looks like this: [self.results removeAllObjects]; [self.keys removeAllObjects]; NSUInteger i,j = 0; NSString *key = [NSString string]; NSString *prevKey = [NSString string]; if ([self.allResults count] > 0) { prevKey = [NSString stringWithString:[[[self.allResults objectAtIndex:0] valueForKey:@"name"] substringToIndex:1]]; for (NSDictionary *theDict in self.allResults) { key = [NSString stringWithString:[[theDict valueForKey:@"name"] substringToIndex:1]]; if (![key isEqualToString:prevKey]) { NSDictionary *newDictionary = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:i],@"count", prevKey,@"section", [NSNumber numberWithInt:j], @"total",nil]; [self.keys addObject:newDictionary]; prevKey = [NSString stringWithString:key]; i = 1; } else { i++; } j++; } NSDictionary *newDictionary = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:i],@"count", prevKey,@"section", [NSNumber numberWithInt:j], @"total",nil]; [self.keys addObject:newDictionary]; } [self.tableview reloadData]; The code works fine first time through but I sometimes have to rebuild the entire table so I redo this code which orks fine on the simulator, but on my device the program bombs when I execute the reloadData line : malloc: *** mmap(size=3772944384) failed (error code=12) *** error: can't allocate region *** set a breakpoint in malloc_error_break to debug malloc: *** mmap(size=3772944384) failed (error code=12) *** error: can't allocate region *** set a breakpoint in malloc_error_break to debug Program received signal: “EXC_BAD_ACCESS”. If I remove the reloadData line the code works on the device. I'm wondering if this is something to do with the way I've built the keys array (ie using autoreleased strings and dictionaries).

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  • How to prevent the beep sound caused by alt key pressed in a WinForms TextBox?

    - by Michael Johnson
    I'm creating a routine that allows the user to replicate keyboard shortcuts into a textbox for 'custom keyboard shortcuts' customization, but every time the alt key is pressed with another letter, it produces another sound. I'm capturing the keys in the textbox_keydown event to parse the modifiers + other keys into a readable Shift + A or Ctrl + Shift + B manner into that very same textbox. Should I be doing this in a different event like textbox_previewkey instead of textbox_keydown? How can I prevent the alt modifier key + a letter or number causing the Beep sound? the textbox is just a normal .net 3.5 textbox with the only edited properties of it being the ReadOnly property to false. Is there a better way I could re-do this? I'm currently just checking that if any modifiers keys are pressed and then + a-z or 0-9, then to go ahead and input the appropriately pressed keys into that same textbox like Shift + A or Ctrl + Shift + Y.

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  • a class function with if(this==NULL) test got compiled?

    - by James
    I saw this code snippet during our lab and it actually compiles in MSVC2008 and G++. void LinkList< class T ::Insert(T n) { if (this == NULL) // some code here } As far as I know the this must not be null since you cannot call a class functions in c++ if it wasn't instantiated. Is this a valid code? if so what's the reason behind and where it can be useful?

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  • Strange client's address returned throug accept(..) function.

    - by Negai
    Hi everyone, I'm a socket programming newbie. Here's a snippet: struct sockaddr_storage client_addr; ... client_addr_size = sizeof(client_addr); client_socket = accept( server_socket, (struct sockaddr *)&client_addr, &client_addr_size ); ... result = inet_ntop( AF_INET, &((struct sockaddr_in *)&client_addr)->sin_addr, client_addr_str, sizeof(client_addr_str) ); Whenever the client connects the address I get is 0.0.0.0 regardless from the host. Can anybody explain, what I'm doing wrong? Thanks.

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  • What's the difference between these two calls to a function taking a collection of structural types?

    - by James Moore
    Why does the call to fn(Iterator("foo") compile, but the call to fn(fooIterator) fail with an error "type mismatch; found : Iterator[java.lang.String] required: scala.Iterator[com.banshee.Qx.HasLength]" object Qx { type HasLength = {def length: Int} def fn(xs: Iterator[HasLength]) = 3 var tn = fn(Iterator("foo")) var fooIterator = Iterator("foo") var tnFails = fn(fooIterator) //doesn't compile } Aren't they the same thing?

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  • How can I specify a relative path in a Python logging config file?

    - by ClaudioA
    I've the following file to config logging: [loggers] keys=root [handlers] keys = root [formatters] keys = generic # Loggers [logger_root] level = DEBUG handlers = root # Handlers [handler_root] class = handlers.RotatingFileHandler args = ("test.log", "maxBytes=1*1024*1024", "backupCount=10") level = NOTSET formatter = generic # Formatters [formatter_generic] format = %(asctime)s,%(msecs)03d %(levelname)-5.5s [%(name)s] %(message)s datefmt = %Y-%m-%d %H:%M:%S In Development this works great, but when I deploy the application test.log is trying to be written in a path in which I don't have the necessary permission. So my question is, How can I do to specify a relative path in this configuration file.

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  • jQuery programming style?

    - by Sam Dufel
    I was recently asked to fix something on a site which I haven't worked on before. I haven't really worked with jQuery that much, but I figured I'd take a look and see if I could fix it. I've managed to mostly clear up the problem, but I'm still horrified at the way they chose to build this site. On document load, they replace the click() method of every anchor tag and form element with the same massive function. When clicked, that function then checks if the tag has one of a few different attributes (non-standard attributes, even), and does a variety of different tasks depending on what attributes exist and what their values are. Some hyperlinks have an attribute on them called 'ajaxrel', which makes the click() function look for another (hidden) hyperlink with an ID specified by the ajaxrel attribute, and then calls the click() function for that other hyperlink (which was also modified by this same click() function). On the server side, all the php files are quite long and have absolutely no indentation. This whole site has been a nightmare to debug. Is this standard jQuery practice? This navigation scheme seems terrible. Does anyone else actually use jQuery this way? I'd like to start incorporating it into my projects, but looking at this site is giving me a serious headache. Here's the click() function for hyperlinks: function ajaxBoxA(theElement, urltosend, ajaxbox, dialogbox) { if ($(theElement).attr("href") != undefined) var urltosend = $(theElement).attr("href"); if ($(theElement).attr('toajaxbox') != undefined) var ajaxbox = $(theElement).attr('toajaxbox'); // check to see if dialog box is called for. if ($(theElement).attr('dialogbox') != undefined) var dialogbox = $(theElement).attr('dialogbox'); var dodialog = 0; if (dialogbox != undefined) { // if dialogbox doesn't exist, then flag to create dialog box. var isDiaOpen = $('[ajaxbox="' + ajaxbox + '"]').parent().parent().is(".ui-dialog-container"); dodialog = 1; if (isDiaOpen) { dodialog = 0; } dialogbox = parseUri(dialogbox); dialogoptions = { close: function () { // $("[id^=hierarchy]",this).NestedSortableDestroy(); $(this).dialog('destroy').remove() } }; for ( var keyVar in dialogbox['queryKey'] ) eval( "dialogoptions." + keyVar + " = dialogbox['queryKey'][keyVar]"); }; $("body").append("<div id='TB_load'><img src='"+imgLoader.src+"' /></div>"); $('#TB_load').show(); if (urltosend.search(/\?/) > 0) { urltosend = urltosend + "&-ajax=1"; } else { urltosend = urltosend + "?-ajax=1"; } if ($('[ajaxbox="' + ajaxbox + '"]').length) { $('[ajaxbox="' + ajaxbox + '"]').each( function () { $(this).empty(); }); }; $.ajax({ type: "GET", url: urltosend, data: "", async: false, dataType: "html", success: function (html) { var re = /^<toajaxbox>(.*?)<\/toajaxbox>+(.*)/; if (re.test(html)) { var match = re.exec(html); ajaxbox = match[1]; html = Right(html, String(html).length - String(match[1]).length); } var re = /^<header>(.*?)<\/header>+(.*)/; if (re.test(html)) { var match = re.exec(html); window.location = match[1]; return false; } if (html.length > 0) { var newHtml = $(html); if ($('[ajaxbox="' + ajaxbox + '"]').length) { $('[ajaxbox="' + ajaxbox + '"]').each( function () { $(this).replaceWith(newHtml).ready( function () { ajaxBoxInit(newHtml) if (window.ajaxboxsuccess) ajaxboxsuccess(newHtml); }); }); if ($('[ajaxdialog="' + ajaxbox + '"]').length = 0) { if (dodialog) $(newHtml).wrap("<div class='flora ui-dialog-content' ajaxdialog='" + ajaxbox + "' style='overflow:auto;'></div>").parent().dialog(dialogoptions); } } else { $("body").append(newHtml).ready( function () { ajaxBoxInit(newHtml); if (window.ajaxboxsuccess) ajaxboxsuccess(newHtml); }); if (dodialog) $(newHtml).wrap("<div class='flora ui-dialog-content' ajaxdialog='" + ajaxbox + "' style='overflow:auto;'></div>").parent().dialog(dialogoptions); } } var rel = $(theElement).attr('ajaxtriggerrel'); if (rel != undefined) $('a[ajaxrel="' + rel + '"]').click(); tb_remove(); return false; }, complete: function () { $("#TB_load").remove(); } }); return false; }

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  • Run javascript function after Server-Side validation is complete.

    - by Ed Woodcock
    Ok, I've got a lightbox with a small form (2 fields) in it, inside an UpdatePanel, and I want to close this lightbox (must be done via javascript) when the 'Save' button is pressed. However, there is a need to have a server-side CustomValidator on the page, and I only want to close the lightbox if this returns as valid. Does anyone know a way to trigger javascript (or jQuery) code from a server-side validator?

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  • Pass Types as arguments to a function in Haskell?

    - by Charles Peng
    The following two functions are extremely similar. They read from a [String] n elements, either [Int] or [Float]. How can I factor the common code out? I don't know of any mechanism in Haskell that supports passing types as arguments. readInts n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Int readFloats n stream = foldl next ([], stream) [1..n] where next (lst, x:xs) _ = (lst ++ [v], xs) where v = read x :: Float I am at a beginner level of Haskell, so any comments on my code are welcome.

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  • jQuery Looking for a function to equalize heights of divs based on tallest image in a table.

    - by Jamie
    I am doing a site that will have a table with a bunch of images in them. They are user added images so I have no control over aspect ratio, what I do have control over is I can the force a max height/width and the image will not exceed this in either direction, but the height can (and will) fluctuate. <table class="pl_upload"> <tr class="row1"> <td class="col1"> <div> <div class="img-container"> <a href="#"><img src="img.jpg" width="182" alt="X" /></a> </div> </div> </td> ....... What I need ideally is to get the height of the tallest image and then make the all of the children divs the same height based on the height of the tallest one. I hope that makes sense, been a long day. I made a jsfiddle page for it here: http://jsfiddle.net/Evolution/27EJB/

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  • Custom permalinks switching function. Please check this logic...

    - by Scott B
    I've got a setting in my theme options panel to allow the user to switch the permalinks setting to support friendly URLs. I'm only allowing /%postname%/ and /%postname%.html as options. I don't want to be triggering an htaccess rewrite everytime someone accesses a page on the site or views theme options, so I'm trying to code this to avoid that. I've got an input field in theme options that's called $myTheme_permalinks. The default value for this is "/%postname%/" but the user can also change it to "/%postname%.html" Here's the code at the top of theme options to handle this setting. Does this look sound? if(get_option('myTheme_permalinks') =="/%postname%/" && get_option('permalink_structure') !== "/%postname%/" || !get_option('myTheme_permalinks')) { require_once(ABSPATH . '/wp-admin/includes/misc.php'); require_once(ABSPATH . '/wp-admin/includes/file.php'); global $wp_rewrite; $wp_rewrite->set_permalink_structure('/%postname%/'); $wp_rewrite->flush_rules(); update_option('permalink_structure','/%postname%/'); update_option('myTheme_permalinks','/%postname%/'); } else if (get_option('myTheme_permalinks') =="/%postname%.html" && get_option('permalink_structure') !== "/%postname%.html" && ) { require_once(ABSPATH . '/wp-admin/includes/misc.php'); require_once(ABSPATH . '/wp-admin/includes/file.php'); global $wp_rewrite; $wp_rewrite->set_permalink_structure('/%postname%.html'); $wp_rewrite->flush_rules(); update_option('permalink_structure','/%postname%.html'); }

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  • Should I use a global var or call the function every time? C++

    - by extintor
    Im using: bool GetOS(LPTSTR pszOS) { OSVERSIONINFOEX osve; BOOL bOsVersionInfoEx; ZeroMemory(&osve, sizeof(OSVERSIONINFOEX)); osve.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX); if( !(bOsVersionInfoEx = GetVersionEx ((OSVERSIONINFO *) &osve)) ) return false; TCHAR buf[80]; StringCchPrintf( buf, 80, TEXT("%u.%u.%u.%u"), osve.dwPlatformId, osve.dwMajorVersion, osve.dwMinorVersion, osve.dwBuildNumber); StringCchCat(pszOS, BUFSIZE, buf); return true; } to get the windows version, and I am planning to use pszOS every a few minutes, Should I use pszOS as a global var or call GetOS() every time? What's the best option from a performance point of view.

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  • Is there an expand.grid like function in R, returning permutations ?

    - by Brani
    To become more specific, here is an example: > expand.grid(5, 5, c(1:4,6),c(1:4,6)) Var1 Var2 Var3 Var4 1 5 5 1 1 2 5 5 2 1 3 5 5 3 1 4 5 5 4 1 5 5 5 6 1 6 5 5 1 2 7 5 5 2 2 8 5 5 3 2 9 5 5 4 2 10 5 5 6 2 11 5 5 1 3 12 5 5 2 3 13 5 5 3 3 14 5 5 4 3 15 5 5 6 3 16 5 5 1 4 17 5 5 2 4 18 5 5 3 4 19 5 5 4 4 20 5 5 6 4 21 5 5 1 6 22 5 5 2 6 23 5 5 3 6 24 5 5 4 6 25 5 5 6 6 This data frame was created from all combinations of the supplied vectors. I would like to create a similar data frame from all permutations of the supplied vectors. Notice that each row must contain exactly 2 fives, yet not necessarily as the fist two elements. Thank you.

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  • Mysql replace() function, help with query (what chars do I escape?)

    - by jyoseph
    I am trying to update an old cms where images were stored in /images/editor/, they are now stored in a bucket on amazon s3. I'm trying to update the database using mysql replace. I've done this in the past with replacing simple words, but now Mysql is reporting an error, I suspect because this is more than a simple word: UPDATE contents SET desc = replace(desc, '/images/editor/', 'http://s3.amazonaws.com/my_bucket/editor/') Do I need to escape the : or slashes? I've tried escaping it with a '\' to no avail. Can someone get me pointed in the right direction? Thanks! Edit Here's the error I am getting, nothing too telling error : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'desc = replace(desc, '/images/editor', 'http://s3.amazonaws.com/app_navigator/ed' at line 1

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