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  • if i call an interface method will it get the method body from implementation class and execute ?

    - by sij
    please forgive me if i am wrong: I have an interface Interface1 I have its implementation Imple implements Interface (all methods hav been implemented :) ) now consider a third class CheckCall can I do a call in the class CheckCall like I mention below Interface1 interface1; interface1.method(); all necessary imports have been done. Please tell me is it possible or not , if not then ok and if yes then tell me what will happen if i have more than one impl classes for the same interface and i am doing the same call.

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  • How to call a PHP class member function from a Java file?

    - by Jack
    I am using PHP/Java bridge to run PHP scripts on the Tomcat server. Can someone point me to an example as to how to call my PHP scripts from a Java file. <?php class X{ //variables //functions } ?> Now I want to call the member functions of class X using its object via a Java file. How do I do this?

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  • In ActionScript3 runtime, is there a way to get a list of all static members from a Class

    - by ty
    Let's say we have following class public class PlayerEvent extends Event { public static const PLAYER_INIT:String = "playerInit"; public static const PLAYER_MOVE:String = "playerMove"; public static const PLAYER_USE_SKILL:String = "playerUseSkill"; public function PlayerEvent(type:String) { super(type, false, true); } } } In Flash Player runtime, is there a way I can get a list of all the static members of lass PlayerEvent. Something like: trace(PlayerEvent.staticMethods) // ["PLAYER_INIT", "PLAYER_MOVE", "PLAYER_USE_SKILL"]...

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  • Is it the best practice to extract an interface for every class?

    - by the_drow
    I have seen code where every class has an interface that it implements. Sometimes there is no common interface for them all. They are just there and they are used instead of concreate objects. They do not offer a generic interface for two classes and are specific to the domain of the problem that the class solves. Is there any reason to do that?

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  • How can I set an intent's class from a string value?

    - by twaxwei
    I am trying to set the class for an intent to the address listed in a string value, so that I can launch a given activity. The string is composed dynamically during runtime. Is there anyway to make something like the code below run: String target=com.test.activity1.class; Intent intent=new intent(); intent.setClass(this, target); Thanks

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  • How do I detect a text input's value and set a class with jQuery?

    - by Zander
    I would like to make sure if a textbox has any content at all, that jQuery can show it's parent (an <li class="hidden_dedication") element and set add a class of 'shown'. I'm pretty sure that it should be something like this, but cannot get it to work: if ($('li.hidden_dedication input').val() !== null) { $(this).parent().show().addClass('shown'); } I cannot figure it out.. any ideas? Many thanks

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  • How to see if type is instance of a class in Haskell?

    - by Raekye
    I'm probably doing this completely wrong (the unhaskell way); I'm just learning so please let me know if there's a better way to approach this. Context: I'm writing a bunch of tree structures. I want to reuse my prettyprint function for binary trees. Not all trees can use the generic Node/Branch data type though; different trees need different extra data. So to reuse the prettyprint function I thought of creating a class different trees would be instances of: class GenericBinaryTree a where is_leaf :: a -> Bool left :: a -> a node :: a -> b right :: a -> a This way they only have to implement methods to retrieve the left, right, and current node value, and prettyprint doesn't need to know about the internal structure. Then I get down to here: prettyprint_helper :: GenericBinaryTree a => a -> [String] prettyprint_helper tree | is_leaf tree = [] | otherwise = ("{" ++ (show (node tree)) ++ "}") : (prettyprint_subtree (left tree) (right tree)) where prettyprint_subtree left right = ((pad "+- " "| ") (prettyprint_helper right)) ++ ((pad "`- " " ") (prettyprint_helper left)) pad first rest = zipWith (++) (first : repeat rest) And I get the Ambiguous type variable 'a0' in the constraint: (Show a0) arising from a use of 'show' error for (show (node tree)) Here's an example of the most basic tree data type and instance definition (my other trees have other fields but they're irrelevant to the generic prettyprint function) data Tree a = Branch (Tree a) a (Tree a) | Leaf instance GenericBinaryTree (Tree a) where is_leaf Leaf = True is_leaf _ = False left (Branch left node right) = left right (Branch left node right) = right node (Branch left node right) = node I could have defined node :: a -> [String] and deal with the stringification in each instance/type of tree, but this feels neater. In terms of prettyprint, I only need a string representation, but if I add other generic binary tree functions later I may want the actual values. So how can I write this to work whether the node value is an instance of Show or not? Or what other way should I be approaching this problem? In an object oriented language I could easily check whether a class implements something, or if an object has a method. I can't use something like prettyprint :: Show a => a -> String Because it's not the tree that needs to be showable, it's the value inside the tree (returned by function node) that needs to be showable. I also tried changing node to Show b => a -> b without luck (and a bunch of other type class/preconditions/whatever/I don't even know what I'm doing anymore).

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  • VMWare vSphere 5: 4 pNICs for iSCSI vs. 2 pNICs

    - by gravyface
    New SAN for me, never used before: it's an IBM DS3512, dual controller with a quad 1GbE NIC per controller that a client bought and needs help setting up. Hosts (x2) have 8 pNICs and while I usually reserve 2 pNICs for iSCSI per host (and 2 for VM, 2 for management, 2 for vMotion, staggered across adapters), these extra ports on the SAN have me wondering if storage I/O would be significantly improved with 2 additional NICs per host, or if the limitations of the vmkernel/initiator would prevent the additional multipaths from ever being realized. I'm not seeing alot of 4 pNIC iSCSI implementations per host; 2 is the de facto standard from what I've read/seen online. I could and probably will do some I/O testing, but just wondering if there's a "wall" that someone else has discovered long ago (i.e. before 10GbE) that makes a 4 NIC iSCSI per host setup somewhat pointless. Just to clarify: I'm not looking for a how-to, but an explanation (link to paper, VMWare recommendation, benchmark, etc.) as to why 2-NIC configurations are the norm vs. 4-NIC iSCSI configurations. i.e. storage vendor limitations, VMKernel/initiator limitations, etc.

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  • Linux Kernel - Red/Black Trees

    - by CodeRanger
    I'm trying to implement a red/black tree in Linux per task_struct using code from linux/rbtree.h. I can get a red/black tree inserting properly in a standalone space in the kernel such as a module but when I try to get the same code to function with the rb_root declared in either task_struct or task_struct-files_struct, I get a SEGFAULT everytime I try an insert. Here's some code: In task_struct I create a rb_root struct for my tree (not a pointer). In init_task.h, macro INIT_TASK(tsk), I set this equal to RB_ROOT. To do an insert, I use this code: rb_insert(&(current-fd_tree), &rbnode); This is where the issue occurs. My insert command is the standard insert that is documented in all RBTree documentation for the kernel: int my_insert(struct rb_root *root, struct mytype *data) { struct rb_node **new = &(root->rb_node), *parent = NULL; /* Figure out where to put new node */ while (*new) { struct mytype *this = container_of(*new, struct mytype, node); int result = strcmp(data->keystring, this->keystring); parent = *new; if (result < 0) new = &((*new)->rb_left); else if (result > 0) new = &((*new)->rb_right); else return FALSE; } /* Add new node and rebalance tree. */ rb_link_node(&data->node, parent, new); rb_insert_color(&data->node, root); return TRUE; } Is there something I'm missing? Some reason this would work fine if I made a tree root outside of task_struct? If I make rb_root inside of a module this insert works fine. But once I put the actual tree root in the task_struct or even in the task_struct-files_struct, I get a SEGFAULT. Can a root node not be added in these structs? Any tips are greatly appreciated. I've tried nearly everything I can think of.

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  • Ruby metaclass madness

    - by t6d
    I'm stuck. I'm trying to dynamically define a class method and I can't wrap my head around the ruby metaclass model. Consider the following class: class Example def self.meta; (class << self; self; end); end def self.class_instance; self; end end Example.class_instance.class # => Class Example.meta.class # => Class Example.class_instance == Example # => true Example.class_instance == Example.meta # => false Obviously both methods return an instance of Class. But these two instances are not the same. They also have different ancestors: Example.meta.ancestors # => [Class, Module, Object, Kernel] Example.class_instance.ancestors # => [Example, Object, Kernel] Whats the point in making a difference between the metaclass and the class instance? I figured out, that I can send :define_method to the metaclass to dynamically define a method, but if I try to send it to the class instance it won't work. At least I could solve my problem, but I still want to understand why it is working this way.

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  • sendto: Invalid Argument

    - by Sylvain
    Hi, I have a list<struct sockaddr_in> _peers I'd like to use for sendto() the list is filled this way struct hostent *hp; hp = gethostbyname(hostname); sockaddr_in sin; bzero(&sin, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_port = htons(port); sin.sin_addr.s_addr = *(in_addr_t *)hp->h_addr; _peers.push_front(sin); and here's how I try to send: for (list<struct sockaddr_in>::iterator it = _peers.begin(); it != _peers.end(); ++it) { if (sendto(_s, "PING", 5, 0, (struct sockaddr *)&(*it), sizeof(struct sockaddr_in)) < 0) perror("sendto"); } outputs: sendto: Invalid argument If I create the struct sockaddr_in right before sendto(), everything works fine, so I guess I fail at using the list properly ... I also tested using &_peers.front() directly and still get the same error ... what am I doing wrong? Thanks in advance,

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  • Boost.Python wrapping hierarchies avoiding diamond inheritance

    - by stbuton
    I'm having some trouble seeing what the best way to wrap a series of classes with Boost.Python while avoiding messy inheritance problems. Say I have the classes A, B, and C with the following structure: struct A { virtual void foo(); virtual void bar(); virtual void baz(); }; struct B : public A { virtual void quux(); }; struct C : public A { virtual void foobar(); }; I want to wrap all classes A, B, and C such that they are extendable from Python. The normal method for accomplishing this would be along the lines of: struct A_Wrapper : public A, boost::python::wrapper<A> { //dispatch logic for virtual functions }; Now for classes B and C which extend from A I would like to be able to inherit and share the wrapping implementation for A. So I'd like to be able to do something along the lines of: struct B_Wrapper : public B, public A_Wrapper, public boost::python::wrapper<B> { //dispatch logic specific for B }; struct C_Wrapper : public C, public A_Wrapper, public boost::python::wrapper<C> { //dispatch logic specific for C } However, it seems like that would introduce all manner of nastiness with the double inheritance of the boost wrapper base and the double inheritance of A in the B_Wrapper and C_Wrapper objects. Is there a common way that this instance is solved that I'm missing? thanks.

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  • c - strncpy issue

    - by Joe
    Hi there, I am getting segmentation fault when using strncpy and (pointer-to-struct)-(member) notation: I have simplified my code. I initialise a struct and set all of it's tokens to an empty string. Then a declare a pointer to a struct and assign the address of the struct to it. I pass the pointer to a function. I can print out the contents of the struct at the beginning of the function, but if I try to use the tp - mnemonic in a strncpy function, I get seg fault. Can anyone tell me what I am doing wrong? typedef struct tok { char* label; char* mnem; char* operand; }Tokens; Tokens* tokenise(Tokens* tp, char* line) { // This prints fine printf("Print this - %s\n", tp -> mnem); // This function gives me segmentation fault strncpy(tp -> mnem, line, 4); return tp; } int main() { char* line = "This is a line"; Tokens tokens; tokens.label = ""; tokens.mnem = "load"; tokens.operand = ""; Tokens* tp = &tokens; tp = tokenise(tp, line); return 0; } I have used printf statements to confirm that the code definitely stops executing at the strncpy function. Can anyone tell me where I am going wrong? Many thanks Joe

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  • C question: error: expected ')' before '*' token

    - by lhw
    ===EDIT I apologize for not putting the pcb struct into the code snippet. There is a struct called pcb defined in above the two structs I originally posted. Namely, typedef struct{ UINT32 proc; struct pcb *link; }pcb; Hi, I asked a question regarding structs in C a few minutes ago and got an answer blazing fast. But now I'm facing another problem, namely the error in the title of this question. I'm trying to implement a simple priority queue in C using arrays of queues. However, when I try to declare a function on pcb_pQ structure, I get the above error. I have the structs clearly defined in the heard file. In the header file: typedef struct{ pcb *head; pcb *tail; SINT32 size; } pcb_Q; typedef struct pcb_pQ { pcb_Q queues[5]; SINT32 size; } pcb_pQ; Function prototype in header file: /*priority queue operations*/ VOID pcb_pq_enqueue(pcb_pQ*, pcb*); Function impelmentation in .c file: VOID pcb_pq_enqueue(pcb_pQ* pcb_pQ, pcb* pcb) { pcb_Q* pcb_Q_p; int priority; priority = pcb->proc_priority; pcb_Q_p = &pcb_pQ->queues[priority]; pcb_enqueue(pcb_Q_p, pcb); } When I try to compile the above code, I get an "error: expected ')' before '*' token". This error is pointing to the function signature in the .c file, namely VOID pcb_pq_enqueue(pcb_pQ* pcb_pQ, pcb* pcb) { But I am not sure why I am getting this error, could someone give me a hand? Thanks a lot.

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  • I want to find the span tag beween the LI tag and its attributes but no luck.

    - by Mahesh
    I want to find the span tag beween the LI tag and its attributes. Trying with beautful soap but no luck. Details of my code. Is any one point me right methodlogy In this this code, my getId function should return me id = "0_False-2" Any one know right method? from BeautifulSoup import BeautifulSoup as bs import re html = '<ul>\ <li class="line">&nbsp;</li>\ <li class="folder-open-last" id="0">\ <img style="float: left;" class="trigger" src="/media/images/spacer.gif" border="0">\ <span class="text" id="0_False">NOC</span><ul style="display: block;"><li class="line">&nbsp;</li><li class="doc" id="1"><span class="active text" id="0_False-1">PNQAIPMS1</span></li><li class="line">&nbsp;</li><li class="doc-last" id="2"><span class="text" id="0_False-2">PNQAIPMS2</span></li><li class="line-last"></li></ul></li><li class="line-last"></li>\ </ul>' def getId(html, txt): soup = bs(html) soup.findAll('ul',recursive=False) head = soup.contents[0] temp = head elements = {} while True: # It temp is None that means no HTML tags are available if temp == None: break #print temp if re.search('li', str( temp)) != None: attr = str(temp.attrs).encode('ascii','ignore') attr = attr.replace(' ', '') attr = attr.replace('[', '') attr = attr.replace(']', '') attr = attr.replace(')', '') attr = attr.replace('(', '') attr = attr.replace('u\'', '') attr = attr.replace('\'', '') attr = attr.split(',') span = str(temp.text) if span == txt: return attr[3] temp = temp.next else: temp = temp.next id = getId(html,"PNQAIPMS2") print "ID = " + id

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  • How to cast sockaddr_storage and avoid breaking strict-aliasing rules

    - by sinoth
    I'm using Beej's Guide to Networking and came across an aliasing issue. He proposes a function to return either the IPv4 or IPv6 address of a particular struct: 1 void *get_in_addr( struct sockaddr *sa ) 2 { 3 if (sa->sa_family == AF_INET) 4 return &(((struct sockaddr_in*)sa)->sin_addr); 5 else 6 return &(((struct sockaddr_in6*)sa)->sin6_addr); 7 } This causes GCC to spit out a strict-aliasing error for sa on line 3. As I understand it, it is because I call this function like so: struct sockaddr_storage their_addr; ... inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr), connection_name, sizeof connection_name); I'm guessing the aliasing has to do with the fact that the their_addr variable is of type sockaddr_storage and another pointer of a differing type points to the same memory. Is the best way to get around this sticking sockaddr_storage, sockaddr_in, and sockaddr_in6 into a union? It seems like this should be well worn territory in networking, I just can't find any good examples with best practices. Also, if anyone can explain exactly where the aliasing issue takes place, I'd much appreciate it.

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  • how to write css for nth child in css

    - by steven spielberg
    <div id="boxcontent"> <div>some content this div may be missing [dynamic genrated]</div> <div class="elem"></div> <div class="elem"></div> <div class="elem"></div> </div> <div id="boxcontent"> <div class="elem"></div> <div class="elem"></div> <div class="elem"></div> </div> <div id="boxcontent"> <div class="elem"></div> <div class="elem"></div> <div class="elem"></div> </div> i want to write some css on every 3rd div who have class .elem if i try nth-child to select them then sometime they select other. How i can select 3rd .elem class div when parent div have some other div as child or not. any way to select 3rd div who have class .elem

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  • Replace textfields with dropdown select fields

    - by 47
    I have three model classes that look as below: class Model(models.Model): model = models.CharField(max_length=20, blank=False) manufacturer = models.ForeignKey(Manufacturer) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = ''+str(self.manufacturer)+" "+str(self.model) return name class Series(models.Model): series = models.CharField(max_length=20, blank=True, null=True) model = models.ForeignKey(Model) date_added = models.DateField(default=datetime.today) def __unicode__(self): name = str(self.model)+" "+str(self.series) return name class Manufacturer(models.Model): MANUFACTURER_POPULARITY_CHOICES = ( ('1', 'Primary'), ('2', 'Secondary'), ('3', 'Tertiary'), ) manufacturer = models.CharField(max_length=15, blank=False) date_added = models.DateField(default=datetime.today) manufacturer_popularity = models.CharField(max_length=1, choices=MANUFACTURER_POPULARITY_CHOICES) def __unicode__(self): return self.manufacturer I want to have the fields for model series and manufacturer represented as dropdowns instead of text fields. I have customized the model forms as below: class SeriesForm(ModelForm): series = forms.ModelChoiceField(queryset=Series.objects.all()) class Meta: model = Series exclude = ('model', 'date_added',) class ModelForm(ModelForm): model = forms.ModelChoiceField(queryset=Model.objects.all()) class Meta: model = Model exclude = ('manufacturer', 'date_added',) class ManufacturerForm(ModelForm): manufacturer = forms.ModelChoiceField(queryset=Manufacturer.objects.all()) class Meta: model = Manufacturer exclude = ('date_added',) However, the dropdowns are populated with the unicode in the respective class...how can I further customize this to get the end result I want? Also, how can I populate the forms with the correct data for editing? Currently only SeriesForm is populated. The starting point of all this is from another class whose declaration is as below: class CommonVehicle(models.Model): year = models.ForeignKey(Year) series = models.ForeignKey(Series) .... def __unicode__(self): name = ''+str(self.year)+" "+str(self.series) return name

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  • memory alignment within gcc structs

    - by Mumbles
    I am porting an application to an ARM platform in C, the application also runs on an x86 processor, and must be backward compatible. I am now having some issues with variable alignment. I have read the gcc manual for __attribute__((aligned(4),packed)) I interpret what is being said as the start of the struct is aligned to the 4 byte boundry and the inside remains untouched because of the packed statement. originally I had this but occasionally it gets placed unaligned with the 4 byte boundary. typedef struct { unsigned int code; unsigned int length; unsigned int seq; unsigned int request; unsigned char nonce[16]; unsigned short crc; } __attribute__((packed)) CHALLENGE; so I change it to this. typedef struct { unsigned int code; unsigned int length; unsigned int seq; unsigned int request; unsigned char nonce[16]; unsigned short crc; } __attribute__((aligned(4),packed)) CHALLENGE; The understand I stated earlier seems to be incorrect as both the struct is now aligned to a 4 byte boundary, and and the inside data is now aligned to a four byte boundary, but because of the endianess, the size of the struct has increased in size from 42 to 44 bytes. This size is critical as we have other applications that depend on the struct being 42 bytes. Could some describe to me how to perform the operation that I require. Any help is much appreciated.

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  • Single Responsibility Principle usage how can i call sub method correctly?

    - by Phsika
    i try to learn SOLID prencibles. i writed two type of code style. which one is : 1)Single Responsibility Principle_2.cs : if you look main program all instance generated from interface 1)Single Responsibility Principle_3.cs : if you look main program all instance genareted from normal class My question: which one is correct usage? which one can i prefer? namespace Single_Responsibility_Principle_2 { class Program { static void Main(string[] args) { IReportManager raporcu = new ReportManager(); IReport wordraporu = new WordRaporu(); raporcu.RaporHazirla(wordraporu, "data"); Console.ReadKey(); } } interface IReportManager { void RaporHazirla(IReport rapor, string bilgi); } class ReportManager : IReportManager { public void RaporHazirla(IReport rapor, string bilgi) { rapor.RaporYarat(bilgi); } } interface IReport { void RaporYarat(string bilgi); } class WordRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Word Raporu yaratildi:{0}",bilgi); } } class ExcellRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Excell raporu yaratildi:{0}",bilgi); } } class PdfRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("pdf raporu yaratildi:{0}",bilgi); } } } Second 0ne all instance genareted from normal class namespace Single_Responsibility_Principle_3 { class Program { static void Main(string[] args) { WordRaporu word = new WordRaporu(); ReportManager manager = new ReportManager(); manager.RaporHazirla(word,"test"); } } interface IReportManager { void RaporHazirla(IReport rapor, string bilgi); } class ReportManager : IReportManager { public void RaporHazirla(IReport rapor, string bilgi) { rapor.RaporYarat(bilgi); } } interface IReport { void RaporYarat(string bilgi); } class WordRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Word Raporu yaratildi:{0}",bilgi); } } class ExcellRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("Excell raporu yaratildi:{0}",bilgi); } } class PdfRaporu : IReport { public void RaporYarat(string bilgi) { Console.WriteLine("pdf raporu yaratildi:{0}",bilgi); } } }

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  • sizeof abuse : get the size of a const table

    - by shodanex
    When declaring a const table, it is possible to get the size of the table using sizeof. However, once you stop using the symbol name, it does not work anymore. is there a way to have the following program output the correct size for table A, instead of 0 ? #include <stdio.h> struct mystruct { int a; short b; }; const struct mystruct tableA[] ={ { .a = 1, .b = 2, }, { .a = 2, .b = 2, }, { .a = 3, .b = 2, }, }; const struct mystruct tableB[] ={ { .a = 1, .b = 2, }, { .a = 2, .b = 2, }, }; int main(int argc, char * argv[]) { int tbl_sz; const struct mystruct * table; table = tableA; tbl_sz = sizeof(table)/sizeof(struct mystruct); printf("size of table A : %d\n", tbl_sz); table = tableB; tbl_sz = sizeof(tableB)/sizeof(struct mystruct); printf("size of table B : %d\n", tbl_sz); return 0; } Output is : size of table A : 0 size of table B : 2

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