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  • Are there any good materials or examples on creating a custom Designer in the Delphi IDE

    - by Mark Elder
    I am working on creating a custom form designer in the Delphi IDE. I'm trying to use the RegisterCustomModule, TBaseCustomModule, and ICustomModule functions, classes, and interfaces. My first question on this pointed me to the Delphi Developer's Handbook and the idea that I could even create a custom form designer. However, that book seems to be all Delphi 3 information and things have really changed since then. I'm not finding any material in the Delphi Help file, and searches have not returned very much. I did find the Accidental Programmer's page on the Open Tools, but that looks like it was last up dated in 1998? It does at least have the correct unit names and uses the new interfaces. I'm willing to track down and buy an older book if that is the best reference.

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  • Updating variables in XSL

    - by Stroboskop
    Is there any way in XSL to update a global variable? I want to check what elements i already transformed and act accordingly. That would require me to somehow add the names of the elements to some sort of list and update it each time a new element is transformed. But since xsl:variable isn't "variable" in the sense one would expect, i have no way of adding anything to it once it has been defined. I have multiple included data files, so using xsl functions that only know the current set of nodes will not help.

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  • matrix = *((fxMatrix*)&d3dMatrix); //Evil?

    - by Xilliah
    I've been using matrix = *((fxMatrix*)&d3dMatrix); for quite a while. It worked fine until my screen turned black and received a bucket of frustration on my desk. fxMatrix contains 4 fxVectors. fxVector used to be 16 bytes, but now it was suddenly 20. This was because it inherited fxStreamable, which added the vTable. So one solution is of course just to not inherit fxStreamable, and leave a comment saying that it must always be 16 bytes and never more. Another solution would be to make conversion functions, and copy the matrix completely. This makes it more secure, but has an impact on the performance. I suppose this is the best idea. Another solution is to not convert at all, and stick to D3DXMATRIX, but this makes the engine inconsistent and I personally really dislike this idea. What is your opinion?

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  • How can unit testing make parameter validation redundant?

    - by Johann Gerell
    We have a convention to validate all parameters of constructors and public functions/methods. For mandatory parameters of reference type, we mainly check for non-null and that's the chief validation in constructors, where we set up mandatory dependencies of the type. The number one reason why we do this is to catch that error early and not get a null reference exception a few hours down the line without knowing where or when the faulty parameter was introduced. As we start transitioning to more and more TDD, some team members feel the validation is redundant. Uncle Bob, who is a vocal advocate of TDD, strongly advices against doing parameter validation. His main argument seems to be "I have a suite of unit tests that makes sure everything works". But I can for the life of it just not see in what way unit tests can prevent our developers from calling these methods with bad parameters in production code. Please, unit testers out there, if you could explain this to me in a rational way with concrete examples, I'd be more than happy to seize this parameter validation!

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  • C++ Basic Class Layout

    - by Spencer
    Learning C++ and see the class laid out like this: class CRectangle { int x, y; public: void set_values (int,int); int area () {return (x*y);} }; void CRectangle::set_values (int a, int b) { x = a; y = b; } I know Java and methods(functions) in Java are written within the class. The class looks like a Java interface. I know I can write the class like this: class CRectangle { int x, y; public: void set_values (int a, int b) { x = a; y = b; }; int area () {return (x*y);} }; But is there a difference or standard?

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  • How to combine two arrays of same length to one array with two fields (not append/merge)

    - by Raj
    Say, I have an array with months $months = array('Jan', 'Feb', 'Mar'...'Dec'); And another, with days (say, for year 2010) $mdays = array(31, 28, 31...31); I want to merge/combine these two arrays, into an array like this: $monthdetails[0] = ('month' => 'Jan', 'days' => 31) $monthdetails[1] = ('month' => 'Feb', 'days' => 28) ... $monthdetails[11] = ('month' => 'Dec', 'days' => 31) I can loop through both the arrays and fill the $monthdetails. I want to know whether there are any functions/easier way for achieving the same result. Thanks! Raj

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  • Alternative to "assign to a function call" in a python

    - by Pythonista's Apprentice
    I'm trying to solve this newbie puzzle: I've created this function: def bucket_loop(htable, key): bucket = hashtable_get_bucket(htable, key) for entry in bucket: if entry[0] == key: return entry[1] else: return None And I have to call it in two other functions (bellow) in the following way: to change the value of the element entry[1] or to append to this list (entry) a new element. But I can't do that calling the function bucket_loop the way I did because "you can't assign to function call" (assigning to a function call is illegal in Python). What is the alternative (most similar to the code I wrote) to do this (bucket_loop(htable, key) = value and hashtable_get_bucket(htable, key).append([key, value]))? def hashtable_update(htable, key, value): if bucket_loop(htable, key) != None: bucket_loop(htable, key) = value else: hashtable_get_bucket(htable, key).append([key, value]) def hashtable_lookup(htable, key): return bucket_loop(htable, key) Thanks, in advance, for any help! This is the rest of the code to make this script works: def make_hashtable(size): table = [] for unused in range(0, size): table.append([]) return table def hash_string(s, size): h = 0 for c in s: h = h + ord(c) return h % size def hashtable_get_bucket(htable, key): return htable[hash_string(key, len(htable))] Similar question (but didn't help me): Python: Cannot Assign Function Call

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  • How to check for C++ copy ellision

    - by Steve
    I ran across this article on copy ellision in C++ and I've seen comments about it in the boost library. This is appealing, as I prefer my functions to look like verylargereturntype DoSomething(...) rather than void DoSomething(..., verylargereturntype& retval) So, I have two questions about this Google has virtually no documentation on this at all, how real is this? How can I check that this optimization is actually occuring? I assume it involves looking at the assembly, but lets just say that isn't my strong suit. If anyone can give a very basic example as to what successful ellision looks like, that would be very useful I won't be using copy ellision just to prettify things, but if I can be guaranteed that it works, it sounds pretty useful.

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  • C++ static virtual members?

    - by cvb
    Is it possible in C++ to have a member function that is both static and virtual? Apperantly, there isn't a straight-forward way to do it (static virtual member(); is a complie error), but at least a way to acheive the same effect? I.E: struct Object { struct TypeInformation; static virtual const TypeInformation &GetTypeInformation() const; }; struct SomeObject : public Object { static virtual const TypeInformation &GetTypeInformation() const; }; It makes sence to use GetTypeInformation() both on an instance (object->GetTypeInformation()) and on a class (SomeObject::GetTypeInformation()), which can be useful for comparsions and vital for templates. The only ways I can think of involves writing two functions / a function and a constant, per class, or use macros. Any other solutions?

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  • WinXP Parallels Guest with OS X host -- communication between the two?

    - by Justin
    The setup: Windows XP guest OS running inside Parallels 5 on a OS X 10.6.2 host. I have a win32 application that runs in windows that communicates with other programs by sending out keystrokes to the program in focus. I can run this software inside parallels just fine, but I need a way for it to communicate (via keystrokes) with native OS X applications. For instance, the windows software sends out a continuous stream of a's and w's, based on the program input from an external source. On the other side, I have a Mac version of VLC media player with hotkeys set up for a and w for the two functions I would like to manipulate from the windows software. How can I set up a link between the guest and host OS's with Parallels that lets a windows program send keystrokes to a mac program?

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  • C++ Vector at/[] operator speed

    - by sub
    In order to give functions the option to modify the vector I can't do curr = myvec.at( i ); doThis( curr ); doThat( curr ); doStuffWith( curr ); But I have to do: doThis( myvec.at( i ) ); doThat( myvec.at( i ) ); doStuffWith( myvec.at( i ) ); (as the answers of my other question pointed out) I'm going to make a hell lot of calls to myvec.at() then. How fast is it, compared to the first example using a variable to store the result? Is there a different option for me? Can I somehow use pointers? When it's getting serious there will be thousands of calls to myvec.at() per second. So every little performance-eater is important.

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  • Separate one-off code paths

    - by DeadMG
    I'm implementing an application with different code paths that shall be chosen once at startup and then fixed forevermore for that execution- for example, choosing D3D11 or D3D9 rendering path. Obviously I don't want to duplicate all my other code. Is run-time inheritance (no virtual inheritance) a fair solution? I don't want to waste a bunch of performance making virtual lookups when the type was fixed long ago. Not just that, but it makes me nervous that the functions can't be inlined and whether or not it affects RVO and NRVO and such. Am I just being over-concerned about this?

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  • Return from parent sub in Perl

    - by JS Bangs
    I want to write a subroutine which causes the caller to return under certain conditions. This is meant to be used as a shortcut for validating input to a function. What I have so far is: sub needs($$) { my ($condition, $message) = @_; if (not $condition) { print "$message\n"; # would like to return from the *parent* here } return $condition; } sub run_find { my $arg = shift @_; needs $arg, "arg required" or return; needs exists $lang{$arg}, "No such language: $arg" or return; # etc. } The advantage of returning from the caller in needs would then be to avoid having to write the repetitive or return inside run_find and similar functions.

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  • i need help to designe code in c++

    - by user344987
    ) Design and implement a Graph data structure. Use adjacency matrix to implement the unweighted graph edges. The Graph must support the following operations: 1.Constructor 2.Destructor 3.Copy constructor 4.A function to add an edge between two nodes in the graph 5.A display function that outputs all the edges of the graph 6.A function edge that accepts two nodes, the function returns true if there is an edge between the passed nodes, and returns false otherwise. B.(100 points) Depth first search and Breadth first search functions. C.(100 points) A function to output a spanning tree of the graph, use any algorithm you find appropriate, also, make the necessary changes on the data structure in A to implement your algorithm.

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  • Why does decorating a class break the descriptor protocol, thus preventing staticmethod objects from behaving as expected?

    - by Robru
    I need a little bit of help understanding the subtleties of the descriptor protocol in Python, as it relates specifically to the behavior of staticmethod objects. I'll start with a trivial example, and then iteratively expand it, examining it's behavior at each step: class Stub: @staticmethod def do_things(): """Call this like Stub.do_things(), with no arguments or instance.""" print "Doing things!" At this point, this behaves as expected, but what's going on here is a bit subtle: When you call Stub.do_things(), you are not invoking do_things directly. Instead, Stub.do_things refers to a staticmethod instance, which has wrapped the function we want up inside it's own descriptor protocol such that you are actually invoking staticmethod.__get__, which first returns the function that we want, and then gets called afterwards. >>> Stub <class __main__.Stub at 0x...> >>> Stub.do_things <function do_things at 0x...> >>> Stub.__dict__['do_things'] <staticmethod object at 0x...> >>> Stub.do_things() Doing things! So far so good. Next, I need to wrap the class in a decorator that will be used to customize class instantiation -- the decorator will determine whether to allow new instantiations or provide cached instances: def deco(cls): def factory(*args, **kwargs): # pretend there is some logic here determining # whether to make a new instance or not return cls(*args, **kwargs) return factory @deco class Stub: @staticmethod def do_things(): """Call this like Stub.do_things(), with no arguments or instance.""" print "Doing things!" Now, naturally this part as-is would be expected to break staticmethods, because the class is now hidden behind it's decorator, ie, Stub not a class at all, but an instance of factory that is able to produce instances of Stub when you call it. Indeed: >>> Stub <function factory at 0x...> >>> Stub.do_things Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: 'function' object has no attribute 'do_things' >>> Stub() <__main__.Stub instance at 0x...> >>> Stub().do_things <function do_things at 0x...> >>> Stub().do_things() Doing things! So far I understand what's happening here. My goal is to restore the ability for staticmethods to function as you would expect them to, even though the class is wrapped. As luck would have it, the Python stdlib includes something called functools, which provides some tools just for this purpose, ie, making functions behave more like other functions that they wrap. So I change my decorator to look like this: def deco(cls): @functools.wraps(cls) def factory(*args, **kwargs): # pretend there is some logic here determining # whether to make a new instance or not return cls(*args, **kwargs) return factory Now, things start to get interesting: >>> Stub <function Stub at 0x...> >>> Stub.do_things <staticmethod object at 0x...> >>> Stub.do_things() Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'staticmethod' object is not callable >>> Stub() <__main__.Stub instance at 0x...> >>> Stub().do_things <function do_things at 0x...> >>> Stub().do_things() Doing things! Wait.... what? functools copies the staticmethod over to the wrapping function, but it's not callable? Why not? What did I miss here? I was playing around with this for a bit and I actually came up with my own reimplementation of staticmethod that allows it to function in this situation, but I don't really understand why it was necessary or if this is even the best solution to this problem. Here's the complete example: class staticmethod(object): """Make @staticmethods play nice with decorated classes.""" def __init__(self, func): self.func = func def __call__(self, *args, **kwargs): """Provide the expected behavior inside decorated classes.""" return self.func(*args, **kwargs) def __get__(self, obj, objtype=None): """Re-implement the standard behavior for undecorated classes.""" return self.func def deco(cls): @functools.wraps(cls) def factory(*args, **kwargs): # pretend there is some logic here determining # whether to make a new instance or not return cls(*args, **kwargs) return factory @deco class Stub: @staticmethod def do_things(): """Call this like Stub.do_things(), with no arguments or instance.""" print "Doing things!" Indeed it works exactly as expected: >>> Stub <function Stub at 0x...> >>> Stub.do_things <__main__.staticmethod object at 0x...> >>> Stub.do_things() Doing things! >>> Stub() <__main__.Stub instance at 0x...> >>> Stub().do_things <function do_things at 0x...> >>> Stub().do_things() Doing things! What approach would you take to make a staticmethod behave as expected inside a decorated class? Is this the best way? Why doesn't the builtin staticmethod implement __call__ on it's own in order for this to just work without any fuss? Thanks.

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  • XCode iPhone OS Deployment Target Tool

    - by Trah Divad
    Problem I'm currently stuck trying to figure out what "iPhone OS Deployment Target" setting to use. I do not want to write conditional code right now, so I'd like the lowest version that runs my application fine. At first I thought it would be 2.0 as I wasn't using any 3.0 features, but then i realized that AVAudioRecorder is a 3.0 API. I don't want to be manually checking EVERY function I use in the documentation. Question Is there a tool that will check the OS availability of each functions you call in your code to figure out what the Deployment Target should be? That tool could be a good old compiler, but the latest version of the iPhone SDK does not come with the PRE-3.0 SDKs.

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  • Is there an equivalent to C++'s "friend class" in Java?

    - by Ricket
    In C++ there is a concept of a "friend", which has access to a class's private variables and functions. So if you have: class Foo { friend class Bar; private: int x; } then any instance of the class Bar can modify any Foo instance's x member, despite it being private, because Bar is a friend of Foo. Now I have a situation in Java where this functionality would come in handy. There are three classes: Database, Modifier, Viewer. The Database is just a collection of variables (like a struct). Modifier should be "friends" with Database; that is, it should be able to read and write its variables directly. But Viewer should only be able to read Database's variables. How is this best implemented? Is there a good way to enforce Viewer's read-only access of Database?

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  • Design pattern: Polymorphism for list of objects

    - by ziang
    Suppose I have a class A, and A1, A2 inherits from A. There are 2 functions: List<A1> getListA1(){...} List<A2> getListA2(){...} Now I want to do something similar to both A1 and A2 in another function public void process(List<A>){...} If I want to pass the instance of either ListA1 or ListA2, of course the types doesn't match because the compiler doesn't allow the coercion from List< A1 to List< A. I can't do something like this: List<A1> listA1 = getListA1(); List<A> newList = (List<A>)listA1; //this is not allowed. So what is the best approach to the process()? Is there any way to do it in a universal way rather than write the similar code to both List and List?

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  • selector for button not working

    - by user1662334
    I want to change the background of the button when the button is unclickable.I have used selector for that but it is not working in the case when the button remains unclickable. This is the selector file: <?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:state_enabled="false" android:drawable="@drawable/button_lightgrey" /> <item android:state_pressed="true" android:state_enabled="true" android:drawable="@drawable/button_blue"/> <item android:state_focused="true" android:drawable="@drawable/button_darkgreen" /> <item android:drawable="@drawable/button_lightgreen" /> </selector> This is the button where i am using this selector file: <Button android:id="@+id/PrevButton" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_centerInParent="true" android:layout_marginLeft="5.0dip" android:layout_weight="1.0" android:background="@drawable/ibtn" android:onClick="onPrevButtonClick" android:text="Prev" /> Please help me.All other functions are working in the selector file but only the unclickable button case is not working.Thanks

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  • advanced search with mysql

    - by Arsenal
    I'm creating a search function for my website where the user can put in anything he likes in a textfield. It get's matched against anything (name, title, job, car brand, ... you name it) I initially wrote the query with an INNER JOIN on every table that needed to be searched. SELECT column1, column2, ... FROM person INNER JOIN person_car ON ... INNER JOIN car ... This ended up in a query with 6 or 8 INNER JOINs, and a whole lot WHERE ... LIKE '%searchvalue%' Now this query seems to cause a time'out in MySql, and I even got a warning from my hosting provider that the queries just taking up too many resources. Now obviously I'm doing this very wrong, but I was wondering how the correct approach to these kind of search functions is. Thanks!

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  • Echo html+php from database

    - by pg-robban
    I am working on a site which deals with a lot of texts in HTML, so recently I learned PHP and moved them into a MySQL database and echo the contents given a specific chapter and section. Now this works relatively fine, the HTML shows up properly. However, in some parts I have included PHP function calls, and these doesn't seem to be evaluated - rather, they get just inserted into the source code (and thus invisible for the page viewer), never doing anything. They did work when they were simple .html files. How can I solve this? For example, a text can look like this: <?php printChapterName(); ?> <p>Some text</p> ... <?php showImage($name, $alt-text); ?> ... This just shows the text on the page. Edit: The functions are echo:ing some HTML.

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  • Partially parse C++ for a domain-specific language

    - by PierreBdR
    I would like to create a domain specific language as an augmented-C++ language. I will need mostly two types of contructs: Top-level constructs for specialized types or declarations In-code constructs, i.e. to add primitives to make functions calls or idiom easier The language will be used for scientific computing purposes, and will ultimately be translated into plain C++. C++ has been chosen as it seems to offer a good compromise between: ease of use, efficiency and availability of a wide range of libraries. A previous attempt using flex and bison failed due to the complexity of the C++ syntax. The existing parser can still fail on some constructs. So we want to start over, but on better bases. Do you know about similar projects? And if you attempted to do so, what tools would you use? What would be the main pitfalls? Would you have recommendations in term of syntax?

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  • Convert bit vector (array of booleans) to an integer, and integer to bit vector, in Java.

    - by dreeves
    What's the best way to unstub the following functions? // Convert a bit-vector to an integer. int bitvec2int(boolean[] b) { [CODE HERE] } // Convert an integer x to an n-element bit-vector. boolean[] int2bitvec(int x, int n) { [CODE HERE] } Or is there a better way to do that sort of thing than passing boolean arrays around? This comes up in an Android app where we need an array of 20 booleans to persist and the easiest way to do that is to write an integer or string to the key-value store. I'll post the way we (Bee and I) wrote the above as an answer. Thanks!

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  • When can we mock an object and its methods?

    - by Shailendra
    I am novice to the Moq and unit testing. I have to write unit tests to a lot of classes which has the objects of other classes. can i mock the methods of the class objects. Here is the exact scenerio- I have a class two classes A and B and A has a private object of B and in a method of A i am internally calling the method of B and then doing some calculation and returning the result. Can i mock the method of B in this scenerio? Please try to give me full detail about the conditions where i can mock the methods and functions of the class. Thanx

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  • Is there anything wrong with a class with all static methods?

    - by MatthewMartin
    I'm doing code review and came across a class that uses all static methods. The entrance method takes several arguments and then starts calling the other static methods passing along all or some of the arguments the entrance method received. It isn't like a Math class with largely unrelated utility functions. In my own normal programming, I rarely write methods where Resharper pops and says "this could be a static method", when I do, they tend to be mindless utility methods. Is there anything wrong with this pattern? Is this just a matter of personal choice if the state of a class is held in fields and properties or passed around amongst static methods using arguments?

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