Search Results

Search found 7722 results on 309 pages for 'pitfalls to avoid'.

Page 64/309 | < Previous Page | 60 61 62 63 64 65 66 67 68 69 70 71  | Next Page >

  • How to build a Django form which requires a delay to be re-submitted ?

    - by pierre-guillaume-degans
    Hey, In order to avoid spamming, I would like to add a waiting time to re-submit a form (i.e. the user should wait a few seconds to submit the form, except the first time that this form is submitted). To do that, I added a timestamp to my form (and a security_hash field containing the timestamp plus the settings.SECRET_KEY which ensures that the timestamp is not fiddled with). This look like: class MyForm(forms.Form): timestamp = forms.IntegerField(widget=forms.HiddenInput) security_hash = forms.CharField(min_length=40, max_length=40, widget=forms.HiddenInput) # + some other fields.. # + methods to build the hash and to clean the timestamp... # (it is based on django.contrib.comments.forms.CommentSecurityForm) def clean_timestamp(self): """Make sure the delay is over (5 seconds).""" ts = self.cleaned_data["timestamp"] if not time.time() - ts > 5: raise forms.ValidationError("Timestamp check failed") return ts # etc... This works fine. However there is still an issue: the timestamp is checked the first time the form is submitted by the user, and I need to avoid this. Any idea to fix it ? Thank you ! :-)

    Read the article

  • SEO, ordering and duplication of content

    - by piquadrat
    I run a specialized news site and am trying to apply a little bit of SEO sauce to it. One of the most important things I hear is to avoid duplication of content. I've covered all the basics but I'm stuck with ordering of content. As an example, the archive of the site is orderable by date, views, and rating. Since we don't have that many news items, an archive page for a particular day has usually only a couple of items, so the following URLs all have the same content, albeit in different ordering: /news/archive/2010/05/16/ /news/archive/2010/05/16/?o=views /news/archive/2010/05/16/?o=rating Do search machines penalize this particular kind of duplication of content? And if yes, what's the best way to avoid said penalty? <link rel="canonical" />? Tell Google & Co. to ingore the o parameter? Marking the ordering links with nofollow? Only allow the indexation of the date-ordered archive sites through robots.txt (not sure if this is even possible)?

    Read the article

  • Set "Start With" value for Oracle sequence dynamically

    - by Allan
    I'm trying to create a release script that can be deployed on multiple databases, but where the data can be merged back together at a later date. The obvious way to handle this is to set the sequence numbers for production data sufficiently high in subsequent deployments to prevent collisions. The problem is in coming up with a release script that will accept the environment number and set the "Start With" value of the sequences appropriately. Ideally, I'd like to use something like this: ACCEPT EnvironNum PROMPT 'Enter the Environment Number: ' --[more scripting] CREATE SEQUENCE seq1 START WITH &EnvironNum*100000; --[more scripting] This doesn't work because you can't evaluate a numeric expression in DDL. Another option is to create the sequences using dynamic SQL via PL/SQL. ACCEPT EnvironNum PROMPT 'Enter the Environment Number: ' --[more scripting] EXEC execute immediate 'CREATE SEQUENCE seq1 START WITH ' || &EnvironNum*100000; --[more scripting] However, I'd prefer to avoid this solution as I generally try to avoid issuing DDL in PL/SQL. Finally, the third option I've come up with is simply to accept the Start With value as a substitution variable, instead of the environment number. Does anyone have a better thought on how to go about this?

    Read the article

  • How is a functional programming-based javascript app laid out?

    - by user321521
    I've been working with node.js for awhile on a chat app (I know, very original, but I figured it'd be a good learning project). Underscore.js provides a lot of functional programming concepts which look interesting, so I'd like to understand how a functional program in javascript would be setup. From my understanding of functional programming (which may be wrong), the whole idea is to avoid side effects, which are basically having a function which updates another variable outside of the function so something like var external; function foo() { external = 'bar'; } foo(); would be creating a side effect, correct? So as a general rule, you want to avoid disturbing variables in the global scope. Ok, so how does that work when you're dealing with objects and what not? For example, a lot of times, I'll have a constructor and an init method that initializes the object, like so: var Foo = function(initVars) { this.init(initVars); } Foo.prototype.init = function(initVars) { this.bar1 = initVars['bar1']; this.bar2 = initVars['bar2']; //.... } var myFoo = new Foo({'bar1': '1', 'bar2': '2'}); So my init method is intentionally causing side effects, but what would be a functional way to handle the same sort of situation? Also, if anyone could point me to either a python or javascript source code of a program that tries to be as functional as possible, that would also be much appreciated. I feel like I'm close to "getting it", but I'm just not quite there. Mainly I'm interested in how functional programming works with traditional OOP classes concept (or does away with it for something different if that's the case).

    Read the article

  • Drupal advanced ACLs for "untrusted" administrators

    - by redShadow
    I have a multi-site Drupal-6 installation containing websites of different customers. On each site, there is an "administrator" role that includes mainly the customer's account. We want to give as many permissions as possible to this privileged user, but this could bring to security leaks using just the Drupal Core permissions management system. The main thing to avoid is the customer account being able to run PHP code on the server (that would be like being logged on the server as the www-data user.. sounds really bad). To avoid that, it is not sufficient to deny PHP code evaluation for the role. Since the administrator role must have permissions to manage users, he could also change the password of the user #1 and login in the site as superadmin. The second goal would be to deny also some "confusing" administrative pages (such as module selection) but not others (such as site informations configuration, or theme selection, etc.) I found the User One module that seems to fix the first problem, but I have no idea on how to solve the second one. I found some modules around, but no-one seems to fit.. it seems like the most ACLs are thought to protect the content, and not the site itself, as if the site administrator would always be the server owner itself..

    Read the article

  • Generating a field setter and getter with ASM

    - by ng
    I would like to avoid reflection in an open source project I am developing. Here I have classes like the following. public class PurchaseOrder { @Property private Customer customer; @Property private String name; } I scan for the @Property annotation to determine what I can set and get from the PurchaseOrder reflectively. There are many such classes all using java.lang.reflect.Field.get() and java.lang.reflect.Field.set(). Ideally I would like to generate for each property an invoker like the following. public interface PropertyAccessor<S, V> { public void set(S source, V value); public V get(S source); } Now when I scan the class I can create a static inner class of PurchaseOrder like so. static class customer_Field implements PropertyAccessor<PurchaseOrder, Customer> { public void set(PurchaseOrder order, Customer customer) { order.customer = customer; } public Customer get(PurchaseOrder order) { return order.customer; } } With these I totally avoid the cost of reflection. I can now set and get from my instances with native performance. Can anyone tell me how I would do this. A code example would be great. I have searched the net for a good example but can find nothing like this. The ASM examples are pretty poor also. The key here is that I have an interface that I can pass around. So I can have various implementations, perhaps one with Java Reflection as a default, one with ASM, and maybe one with Javassist? Any help would be greatly appreciated.

    Read the article

  • Where should I store shared resources between LocalSystem and regular user with UAC?

    - by rwired
    My application consists of two parts: A Windows Service running under the LocalSystem account and a client process running under the currently logged in regular user. I need to deploy the application across Windows versions from XP up to Win7. The client will retrieve files from the web and collect user data from the user. The service will construct files and data of it's own which the client needs to read. I'm trying to figure out the best place (registry or filesystem, or mix) to store all this. One file the client or service needs to be able to retrieve from the net is an update_patch executable which needs to run whenever an upgrade is available. I need to be sure the initial installer SETUP.EXE, and also the update_patch can figure out this ideal location and set a RegKey to be read later by both client and server telling them the magic location (The SETUP.EXE will run with elevated privileges since it needs to install the service) On my Win7 test system the service %APPDATA% points to: C:\Windows\system32\config\systemprofile\AppData\Roaming and the %APPDATA% of the client points to: C:\Users\(username)\AppData\Roaming Interestingly Google Chrome stores everything (App and Data) in C:\Users\(username)\AppData\Local\Google\Chrome Chrome runs pretty much in exactly the way I want my suite to run (able to silently update itself in the background) What I'm trying to avoid is nasty popups warning the user that the app wants to modify the system, and I want to avoid problems when VirtualStore doesn't exist because the user is running XP/2000/2003 or has UAC turned off. My target audience are non-tech-savvy general Windows users.

    Read the article

  • Database localization

    - by Don
    Hi, I have a number of database tables that contain name and description columns which need to be localized. My initial attempt at designing a DB schema that would support this was something like: product ------- id name description local_product ------- id product_id local_name local_description locale_id locale ------ id locale However, this solution requires a new local_ table for every table that contains name and description columns that require localization. In an attempt to avoid this overhead I redesigned the schema so that only a single localization table is needed product ------- id localization_id localization ------- id local_name local_description locale_id locale ------ id locale Here's an example of the data which would be stored in this schema when there are 2 tables (product and country) requiring localization: country id, localization_id ----------------------- 1, 5 product id, localization_id ----------------------- 1, 2 localization id, local_name, local_description, locale_id ------------------------------------------------------ 2, apple, a delicious fruit, 2 2, pomme, un fruit délicieux, 3 2, apfel, ein köstliches Obst, 4 5, ireland, a small country, 2 5, irlande, un petite pay, 3 locale id, locale -------------- 2, en 3, fr 4, de Notice that the compound primary key of the localization table is (id, locale_id), but the foreign key in the product table only refers to the first element of this compound PK. This seems like 'a bad thing' from the POV of normalization. Is there any way I can fix this problem, or alternatively, is there a completely different schema that supports localization without creating a separate table for each localizable table? Update: A number of respondents have proposed a solution that requires creating a separate table for each localizable table. However, this is precisely what I'm trying to avoid. The schema I've proposed above almost solves the problem to my satisfaction, but I'm unhappy about the fact that the localization_id foreign keys only refer to part of the corresponding primary key in the localization table. Thanks, Don

    Read the article

  • How can I prevent the "... has stopped working" window on my Server 2008 R2 dev box?

    - by serialhobbyist
    I'm using a Windows Server 2008 x64 R2 machine as a development box. Amongst many other things I've got Visual Studio 2008 SP1 installed on it. When I'm working on a project, I sometimes need to use Debug Start without Debugging (Ctrl + F5). If the program throws an exception, I get a new R2-style window appear. I'm pretty sure I didn't see this on my XP box - this is the first time I've developed directly on a server. Is there any way to avoid this - it's really beginning to bug me? E.g. my current project is accessing a WCF service - I'm using Ctrl+F5 to start a console program client. I run it and get the window. The title is the name of the project I've just started and it contains: [insert-project-name-here] has stopped working Windows can check online for a solution to the problem. --> Check online for a solution and close the program --> Close the program --> Debug the program V View problem details. Clicking on "Close the program" will actually close the window and the exception message appears in the console, which is what I want (but without the extra window-faffing). How can I avoid this annoyance?

    Read the article

  • Python and the self parameter

    - by Svend
    I'm having some issues with the self parameter, and some seemingly inconsistent behavior in Python is annoying me, so I figure I better ask some people in the know. I have a class, Foo. This class will have a bunch of methods, m1, through mN. For some of these, I will use a standard definition, like in the case of m1 below. But for others, it's more convinient to just assign the method name directly, like I've done with m2 and m3. import os def myfun(x, y): return x + y class Foo(): def m1(self, y, z): return y + z + 42 m2 = os.access m3 = myfun f = Foo() print f.m1(1, 2) print f.m2("/", os.R_OK) print f.m3(3, 4) Now, I know that os.access does not take a self parameter (seemingly). And it still has no issues with this type of assignment. However, I cannot do the same for my own modules (imagine myfun defined off in mymodule.myfun). Running the above code yields the following output: 3 True Traceback (most recent call last): File "foo.py", line 16, in <module> print f.m3(3, 4) TypeError: myfun() takes exactly 2 arguments (3 given) The problem is that, due to the framework I work in, I cannot avoid having a class Foo at least. But I'd like to avoid having my mymodule stuff in a dummy class. In order to do this, I need to do something ala def m3(self,a1, a2): return mymodule.myfun(a1,a2) Which is hugely redundant when you have like 20 of them. So, the question is, either how do I do this in a totally different and obviously much smarter way, or how can I make my own modules behave like the built-in ones, so it does not complain about receiving 1 argument too many.

    Read the article

  • How can I keep an event from being delivered to the GUI until my code finished running?

    - by Frerich Raabe
    I installed a global mouse hook function like this: mouseEventHook = ::SetWindowsHookEx( WH_MOUSE_LL, mouseEventHookFn, thisModule, 0 ); The hook function looks like this: RESULT CALLBACK mouseEventHookFn( int code, WPARAM wParam, LPARAM lParam ) { if ( code == HC_ACTION ) { PMSLLHOOKSTRUCT mi = (PMSLLHOOKSTRUCT)lParam; // .. do interesting stuff .. } return ::CallNextHookEx( mouseEventHook, code, wParam, lParam ); } Now, my problem is that I cannot control how long the 'do interesting stuff' part takes exactly. In particular, it might take longer than the LowLevelHooksTimeout defined in the Windows registry. This means that, at least on Windows XP, the system no longer delivers mouse events to my hook function. I'd like to avoid this, but at the same time I need the 'do interesting stuff' part to happen before the target GUI receives the event. I attempted to solve this by doing the 'interesting stuff' work in a separate thread so that the mouseEventHookFn above can post a message to the worker thread and then do a return 1; immediately (which ends the hook function but avoids that the event is handed to the GUI). The idea was that the worker thread, when finished, performs the CallNextHookEx call itself. However, this causes a crash inside of CallNextHookEx (in fact, the crash occurs inside an internal function called PhkNextValid. I assume it's not safe to call CallNextHookEx from outside a hook function, is this true? If so, does anybody else know how I can run code (which needs to interact with the GUI thread of an application) before the GUI receives the event and avoid that my hook function blocks too long?

    Read the article

  • C callback functions defined in an unnamed namespace?

    - by Johannes Schaub - litb
    Hi all. I have a C++ project that uses a C bison parser. The C parser uses a struct of function pointers to call functions that create proper AST nodes when productions are reduced by bison: typedef void Node; struct Actions { Node *(*newIntLit)(int val); Node *(*newAsgnExpr)(Node *left, Node *right); /* ... */ }; Now, in the C++ part of the project, i fill those pointers class AstNode { /* ... */ }; class IntLit : public AstNode { /* ... */ }; extern "C" { Node *newIntLit(int val) { return (Node*)new IntLit(val); } /* ... */ } Actions createActions() { Actions a; a.newIntLit = &newIntLit; /* ... */ return a; } Now the only reason i put them within extern "C" is because i want them to have C calling conventions. But optimally, i would like their names still be mangled. They are never called by-name from C code, so name mangling isn't an issue. Having them mangled will avoid name conflicts, since some actions are called like error, and the C++ callback function has ugly names like the following just to avoid name clashes with other modules. extern "C" { void uglyNameError(char const *str) { /* ... */ } /* ... */ } a.error = &uglyNameError; I wondered whether it could be possible by merely giving the function type C linkage extern "C" void fty(char const *str); namespace { fty error; /* Declared! But i can i define it with that type!? */ } Any ideas? I'm looking for Standard-C++ solutions.

    Read the article

  • Can I force the auto-generated Linq-to-SQL classes to use an OUTER JOIN?

    - by Gary McGill
    Let's say I have an Order table which has a FirstSalesPersonId field and a SecondSalesPersonId field. Both of these are foreign keys that reference the SalesPerson table. For any given order, either one or two salespersons may be credited with the order. In other words, FirstSalesPersonId can never be NULL, but SecondSalesPersonId can be NULL. When I drop my Order and SalesPerson tables onto the "Linq to SQL Classes" design surface, the class builder spots the two FK relationships from the Order table to the SalesPerson table, and so the generated Order class has a SalesPerson field and a SalesPerson1 field (which I can rename to SalesPerson1 and SalesPerson2 to avoid confusion). Because I always want to have the salesperson data available whenever I process an order, I am using DataLoadOptions.LoadWith to specify that the two salesperson fields are populated when the order instance is populated, as follows: dataLoadOptions.LoadWith<Order>(o => o.SalesPerson1); dataLoadOptions.LoadWith<Order>(o => o.SalesPerson2); The problem I'm having is that Linq to SQL is using something like the following SQL to load an order: SELECT ... FROM Order O INNER JOIN SalesPerson SP1 ON SP1.salesPersonId = O.firstSalesPersonId INNER JOIN SalesPerson SP2 ON SP2.salesPersonId = O.secondSalesPersonId This would make sense if there were always two salesperson records, but because there is sometimes no second salesperson (secondSalesPersonId is NULL), the INNER JOIN causes the query to return no records in that case. What I effectively want here is to change the second INNER JOIN into a LEFT OUTER JOIN. Is there a way to do that through the UI for the class generator? If not, how else can I achieve this? (Note that because I'm using the generated classes almost exclusively, I'd rather not have something tacked on the side for this one case if I can avoid it).

    Read the article

  • C++ Builder 2010 Exception Dead Lock ???

    - by James
    Hello Is this some kind of exception dead lock i am facing? How to avoid it ? Have a look at below line where i have TIdContext objects of connected clients stored in an objlist and at times i need to process it. But if one user is disconnected while another thread is processing the list, then for that freed TIdContext-Data object I am getting Access voilation, Ok its fine i am using try/catch but problem is that at below line there is some kind of dead lock and process hangs , if i attach a debuger it show Access voilation Again and Again and Again, and cpu coonsumption goes up because of that exception dead lock. AnsiString UserID = ((Tmyobject*) ((TIdContext*) ObjList->Objects[i])->Data)->UserID; i know i can check before accessing the object, if object is not Null, It works.. But my question is what if once in a blue moon the Data object is freed at the point when NULL check is performed and on next line when again i am accessing the object i get same dead lock ??? So how to avoid/handle this dead lock exception ? Here is the call stack... :005F07C0 System::AnsiStringBase::AnsiStringBase(this=:0285FCE0, src=????) :0040223F System::AnsiStringT<0>::AnsiStringT<0>(this=:0285FCE0, src=:00000008) :00457996 TSomeClass::SomeFunction(this=:009D8230, UserID={ }, DataSize={ }, ) :0047BFF1 __linkproc__ ThreadProc(Thread=:009561C0) :004AD00E __linkproc__ ThreadWrapper(Parameter=:009EAA30) :7c80b729 ; C:\WINDOWS\system32\kernel32.dll Please helppppppppppppppppppppp Thanks

    Read the article

  • django: results in in_bulk style without IDs

    - by valya
    in django 1.1.1, Place.objects.in_bulk() does not work and Place.objects.in_bulk(range(1, 100)) works and returns a dictionary of Ints to Places with indexes - primary keys. How to avoid using range in this situation (and avoid using a special query for ids, I just want to get all objects in this dictionary format) >>> Place.objects.in_bulk() Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/lib/python2.5/site-packages/Django-1.1.1-py2.5.egg/django/db/models/manager.py", line 144, in in_bulk return self.get_query_set().in_bulk(*args, **kwargs) TypeError: in_bulk() takes exactly 2 arguments (1 given) >>> Place.objects.in_bulk(range(1, 100)) {1L: <Place: "??? ????">, 3L: <Place: "???????????? ?????">, 4L: <Place: "????????? "??????"">, 5L: <Place: "????????? "??????"">, 8L: <Place: "????????? "??????????????"">, 9L: <Place: "??????? ????????">, 10L: <Place: "????????? ???????">, 11L: <Place: "??????????????? ???">, 14L: <Place: "????? ????? ??????">}

    Read the article

  • To OpenID or not to OpenID? Is it worth it?

    - by Eloff
    Does OpenID improve the user experience? Edit Not to detract from the other comments, but I got one really good reply below that outlined 3 advantages of OpenID in a rational bottom line kind of way. I've also heard some whisperings in other comments that you can get access to some details on the user through OpenID (name? email? what?) and that using that it might even be able to simplify the registration process by not needing to gather as much information. Things that definitely need to be gathered in a checkout process: Full name Email (I'm pretty sure I'll have to ask for these myself) Billing address Shipping address Credit card info There may be a few other things that are interesting from a marketing point of view, but I wouldn't ask the user to manually enter anything not absolutely required during the checkout process. So what's possible in this regard? /Edit (You may have noticed stackoverflow uses OpenID) It seems to me it is easier and faster for the user to simply enter a username and password in a signup form they have to go through anyway. I mean you don't avoid entering a username and password either with OpenID. But you avoid the confusion of choosing a OpenID provider, and the trip out to and back from and external site. With Microsoft making Live ID an OpenID provider (More Info), bringing on several hundred million additional accounts to those provided by Google, Yahoo, and others, this question is more important than ever. I have to require new customers to sign up during the checkout process, and it is absolutely critical that the experience be as easy and smooth as possible, every little bit harder it becomes translates into lost sales. No geek factor outweighs cold hard cash at the end of the day :) OpenID seems like a nice idea, but the implementation is of questionable value. What are the advantages of OpenID and is it really worth it in my scenario described above?

    Read the article

  • JavaScript automatically converts some special characters

    - by noplacetoh1de
    I need to extract a HTML-Substring with JS which is position dependent. I store special characters HTML-encoded. For example: HTML <div id="test"><p>l&ouml;sen &amp; gr&uuml;&szlig;en</p></div>? Text lösen & grüßen My problem lies in the JS-part, for example when I try to extract the fragment lö, which has the HTML-dependent starting position of 3 and the end position of 9 inside the <div> block. JS seems to convert some special characters internally so that the count from 3 to 9 is wrongly interpreted as "lösen " and not "l&ouml;". Other special characters like the &amp; are not affected by this. So my question is, if someone knows why JS is behaving in that way? Characters like &auml; or &ouml; are being converted while characters like &amp; or &nbsp; are plain. Is there any possibility to avoid this conversion? I've set up a fiddle to demonstrate this: JSFiddle Thanks for any help! EDIT: Maybe I've explained it a bit confusing, sorry for that. What I want is the HTML: <p>l&ouml;sen &amp; gr&uuml;&szlig;en</p> . Every special character should be unconverted, except the HTML-Tags. Like in the HTML above. But JS converts the &ouml; or &uuml; into ö or ü automatically, what I need to avoid.

    Read the article

  • Why do .NET developers offer 32-bit/64-bit versions of .NET assemblies?

    - by Tyler
    Evey now and then I see both x86 and x64 versions of a .NET assembly. Consider the following web part for SharePoint. Why wouldn't the developer just offer a single version and have let the JIT compiler sort out the rest? When I see these kinds offering is it just that the developer decided to create a native image using a tool like ngen in order to avoid a JIT? Someone please help me out here, I feel like I'm missing something of note. Updated From what I got below, both x86 and x64 builds are offered because one or more of the following reasons: The developer wanted to avoid JITing and created a native image of his code, targeting a given architecture using a tool like ngen.exe. The assembly contains platform specific COM calls and so it makes no point to build it as AnyCPU. In these cases builds that target different platforms may contain different code. The assembly may contain Win32 calls using pinvoke which won't get remapped by a JIT and so the build should target the platform it is bound to.

    Read the article

  • Strategies for dealing with Circular references caused by JPA relationships?

    - by ams
    I am trying to partition my application into modules by features packaged into separate jars such as feature-a.jar, feature-b.jar, ... etc. Individual feature jars such as feature-a.jar should contain all the code for a feature a including jpa entities, business logic, rest apis, unit tests, integration test ... etc. The problem I am running into is that bi-directional relationships between JPA entities cause circular references between the jar files. For example Customer entity should be in customer.jar and the Order should be in order.jar but Customer references order and order references customer making it hard to split them into separate jars / eclipse projects. Options I see for dealing with the circular dependencies in JPA entities: Option 1: Put all the entities into one jar / one project Option 2: Don't map certain bi-directianl relationships to avoid circular dependencies across projects. Questions: What rules / principles have you used to decide when to do bi-directional mapping vs. not? Have you been able to break jpa entities into their own projects / jar by features if so how did you avoid the circular dependencies issues?

    Read the article

  • Questions on Juval Lowy's IDesign C# Coding Standard

    - by Jan
    We are trying to use the IDesign C# Coding standard. Unfortunately, I found no comprehensive document to explain all the rules that it gives, and also his book does not always help. Here are the open questions that remain for me (from chapter 2, Coding Practices): No. 26: Avoid providing explicit values for enums unless they are integer powers of 2 No. 34: Always explicitly initialize an array of reference types using a for loop No. 50: Avoid events as interface members No. 52: Expose interfaces on class hierarchies No. 73: Do not define method-specific constraints in interfaces No. 74: Do not define constraints in delegates Here's what I think about those: I thought that providing explicit values would be especially useful when adding new enum members at a later point in time. If these members are added between other already existing members, I would provide explicit values to make sure the integer representation of existing members does not change. No idea why I would want to do this. I'd say this totally depends on the logic of my program. I see that there is alternative option of providing "Sink interfaces" (simply providing already all "OnXxxHappened" methods), but what is the reason to prefer one over the other? Unsure what he means here: Could this mean "When implementing an interface explicitly in a non-sealed class, consider providing the implementation in a protected virtual method that can be overridden"? (see Programming .NET Components 2nd Edition, end of chapter “Interfaces and Class Hierarchies”). I suppose this is about providing a "where" clause when using generics, but why is this bad on an interface? I suppose this is about providing a "where" clause when using generics, but why is this bad on a delegate?

    Read the article

  • python list/dict property best practice

    - by jterrace
    I have a class object that stores some properties that are lists of other objects. Each of the items in the list has an identifier that can be accessed with the id property. I'd like to be able to read and write from these lists but also be able to access a dictionary keyed by their identifier. Let me illustrate with an example: class Child(object): def __init__(self, id, name): self.id = id self.name = name class Teacher(object): def __init__(self, id, name): self.id = id self.name = name class Classroom(object): def __init__(self, children, teachers): self.children = children self.teachers = teachers classroom = Classroom([Child('389','pete')], [Teacher('829','bob')]) This is a silly example, but it illustrates what I'm trying to do. I'd like to be able to interact with the classroom object like this: #access like a list print classroom.children[0] #append like it's a list classroom.children.append(Child('2344','joe')) #delete from like it's a list classroom.children.pop(0) But I'd also like to be able to access it like it's a dictionary, and the dictionary should be automatically updated when I modify the list: #access like a dict print classroom.childrenById['389'] I realize I could just make it a dict, but I want to avoid code like this: classroom.childrendict[child.id] = child I also might have several of these properties, so I don't want to add functions like addChild, which feels very un-pythonic anyway. Is there a way to somehow subclass dict and/or list and provide all of these functions easily with my class's properties? I'd also like to avoid as much code as possible.

    Read the article

  • Prolog singleton variables in Python

    - by Rubens
    I'm working on a little set of scripts in python, and I came to this: line = "a b c d e f g" a, b, c, d, e, f, g = line.split() I'm quite aware of the fact that these are decisions taken during implementation, but shouldn't (or does) python offer something like: _, _, var_needed, _, _, another_var_needed, _ = line.split() as well as Prolog does offer, in order to exclude the famous singleton variables. I'm not sure, but wouldn't it avoid unnecessary allocation? Or creating references to the result of the split call does not count up as overhead? EDIT: Sorry, my point here is: in Prolog, as far as I'm concerned, in an expression like: test(L, N) :- test(L, 0, N). test([], N, N). test([_|T], M, N) :- V is M + 1, test(T, V, N). The variable represented by _ is not accessible, for what I suppose the reference to the value that does exist in the list [_|T] is not even created. But, in Python, if I use _, I can use the last value assigned to _, and also, I do suppose the assignment occurs for each of the variables _ -- which may be considered an overhead. My question here is if shouldn't there be (or if there is) a syntax to avoid such unnecessary attributions.

    Read the article

  • Lightweight HTTP application/server for static content

    - by PartlyCloudy
    Hi, I am in need of a scalable and performant HTTP application/server that will be used for static file serving/uploading. So I only need support for GET and PUT operations. However, there are a few extra features that I need: Custom authentication: I need to check credentials against a database for each request. Thus I must be able to integrate propietary database interaction. Support for signed access keys: The access to resources via PUT should be signed using a key like http://uri/?key=foo The key then contains information about the request like md5(user + path + secret) which allows me to block unwanted requests. The application/server should allow me to check for this. Performance: I'd like to avoid piping content as much as possible. Otherwise the whole application could be implemented in Perl/etc. in a few lines as CGI. Perlbal (in webserver mode) looks nice, however the single-threaded model does not fit with my database lookup and it does also not support query strings. Lighttp/Nginx/… have some modules for these tasks, however it is not feasible putting everything together without ending up writing own extensions/modules. So how would you solve this? Are there other leightweight webservers available for this? Should I implement an application inside of a webserver (i.e. CGI). How can I avoid/speed up piping content between the webserver and my application. Thanks in advance!

    Read the article

  • How can I concisely copy multiple SQL rows, with minor modifications?

    - by Steve Jessop
    I'm copying a subset of some data, so that the copy will be independently modifiable in future. One of my SQL statements looks something like this (I've changed table and column names): INSERT Product( ProductRangeID, Name, Weight, Price, Color, And, So, On ) SELECT @newrangeid AS ProductRangeID, Name, Weight, Price, Color, And, So, On FROM Product WHERE ProductRangeID = @oldrangeid and Color = 'Blue' That is, we're launching a new product range which initially just consists of all the blue items in some specified current range, under new SKUs. In future we may change the "blue-range" versions of the products independently of the old ones. I'm pretty new at SQL: is there something clever I should do to avoid listing all those columns, or at least avoid listing them twice? I can live with the current code, but I'd rather not have to come back and modify it if new columns are added to Product. In its current form it would just silently fail to copy the new column if I forget to do that, which should show up in testing but isn't great. I am copying every column except for the ProductRangeID (which I modify), the ProductID (incrementing primary key) and two DateCreated and timestamp columns (which take their auto-generated values for the new row). Btw, I suspect I should probably have a separate join table between ProductID and ProductRangeID. I didn't define the tables. This is in a T-SQL stored procedure on SQL Server 2008, if that makes any difference.

    Read the article

  • Replacing words in string

    - by abkai
    Okay, so I have the following little function: def swap(inp): inp = inp.split() out = "" for item in inp: ind = inp.index(item) item = item.replace("i am", "you are") item = item.replace("you are", "I am") item = item.replace("i'm", "you're") item = item.replace("you're", "I'm") item = item.replace("my", "your") item = item.replace("your", "my") item = item.replace("you", "I") item = item.replace("my", "your") item = item.replace("i", "you") inp[ind] = item for item in inp: ind = inp.index(item) item = item + " " inp[ind] = item return out.join(inp) Which, while it's not particularly efficient gets the job done for shorter sentences. Basically, all it does is swaps pronoun etc. perspectives. This is fine when I throw a string like "I love you" at it, it returns "you love me" but when I throw something like: you love your version of my couch because I love you, and you're a couch-lover. I get: I love your versyouon of your couch because I love I, and I'm a couch-lover. I'm confused as to why this is happening. I explicitly split the string into a list to avoid this. Why would it be able to detect it as being a part of a list item, rather than just an exact match? Also, slightly deviating to avoid having to post another question so similar; if a solution to this breaks this function, what will happen to commas, full stops, other punctuation? It made some very surprising mistakes. My expected output is: I love my version of your couch because you love I, and I'm a couch-lover. The reason I formatted it like this, is because I eventually hope to be able to replace the item.replace(x, y) variables with words in a database.

    Read the article

< Previous Page | 60 61 62 63 64 65 66 67 68 69 70 71  | Next Page >