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  • Destructors not called when native (C++) exception propagates to CLR component

    - by Phil Nash
    We have a large body of native C++ code, compliled into DLLs. Then we have a couple of dlls containing C++/CLI proxy code to wrap the C++ interfaces. On top of that we have C# code calling into the C++/CLI wrappers. Standard stuff, so far. But we have a lot of cases where native C++ exceptions are allowed to propagate to the .Net world and we rely on .Net's ability to wrap these as System.Exception objects and for the most part this works fine. However we have been finding that destructors of objects in scope at the point of the throw are not being invoked when the exception propagates! After some research we found that this is a fairly well known issue. However the solutions/ workarounds seem less consistent. We did find that if the native code is compiled with /EHa instead of /EHsc the issue disappears (at least in our test case it did). However we would much prefer to use /EHsc as we translate SEH exceptions to C++ exceptions ourselves and we would rather allow the compiler more scope for optimisation. Are there any other workarounds for this issue - other than wrapping every call across the native-managed boundary in a (native) try-catch-throw (in addition to the C++/CLI layer)?

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  • Error when compiling a WinForms project that uses SubSonic library

    - by Mike Devenney
    The code generation is working but I get the following errors when I try to build the project: Error 4 Source file '...Project Path...\Structs.cs' could not be opened ('Unspecified error ') PPSGenerator Error 5 Source file '...Project Path...\Context.cs' could not be opened ('Unspecified error ') PPSGenerator Error 6 Source file '...Project Path...\ActiveRecord.cs' could not be opened ('Unspecified error ') PPSGenerator Error 7 Source file '...Project Path...\StoredProcedures.cs' could not be opened ('Unspecified error ') PPSGenerator I'm using VS2010 on a Windows 7 64 bit machine. Project is targeting Framework 3.5... any ideas? Also noticed the following warnings, but not sure that these are as important: Warning 1 The C# 2.0 and C# 3.5 compilers are no longer supported. Templates will always be compiled with the version 4 compiler instead of 'v3.5' as specified. ...ProjectPath...\Structs.tt 1 4 Warning 2 Multiple template directives were found in the template. All but the first one will be ignored. Multiple parameters to the template directive should be specified within one template directive. ...ProjectPath...\Settings.ttinclude 1 4 Warning 3 Compiling transformation: The variable 'parameters' is assigned but its value is never used ...ProjectPath...\SQLServer.ttinclude 92 15 Thanks! Mike D

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  • actionscript-3: refactor interface inheritance to get rid of ambiguous reference error

    - by maxmc
    hi! imagine there are two interfaces arranged via composite pattern, one of them has a dispose method among other methods: interface IComponent extends ILeaf { ... function dispose() : void; } interface ILeaf { ... } some implementations have some more things in common (say an id) so there are two more interfaces: interface ICommonLeaf extends ILeaf { function get id() : String; } interface ICommonComponent extends ICommonLeaf, IComponent { } so far so good. but there is another interface which also has a dispose method: interface ISomething { ... function dispose() : void; } and ISomething is inherited by ICommonLeaf: interface ICommonLeaf extends ILeaf, ISomething { function get id() : String; } As soon as the dispose method is invoked on an instance which implements the ICommonComponent interface, the compiler fails with an ambiguous reference error because ISomething has a method called dispose and ILeaf also has a dispose method, both living in different interfaces (IComponent, ISomething) within the inheritace tree of ICommonComponent. I wonder how to deal with the situation if the IComponent, the ILeaf and the ISomething can't change. the composite structure must also work for for the ICommonLeaf & ICommonComponent implementations and the ICommonLeaf & ICommonComponent must conform to the ISomething type. this might be an actionscript-3 specific issue. i haven't tested how other languages (for instance java) handle stuff like this.

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  • How to write a bison grammer for WDI?

    - by Rizo
    I need some help in bison grammar construction. From my another question: I'm trying to make a meta-language for writing markup code (such as xml and html) wich can be directly embedded into C/C++ code. Here is a simple sample written in this language, I call it WDI (Web Development Interface): /* * Simple wdi/html sample source code */ #include <mySite> string name = "myName"; string toCapital(string str); html { head { title { mySiteTitle; } link(rel="stylesheet", href="style.css"); } body(id="default") { // Page content wrapper div(id="wrapper", class="some_class") { h1 { "Hello, " + toCapital(name) + "!"; } // Lists post ul(id="post_list") { for(post in posts) { li { a(href=post.getID()) { post.tilte; } } } } } } } Basically it is a C source with a user-friendly interface for html. As you can see the traditional tag-based style is substituted by C-like, with blocks delimited by curly braces. I need to build an interpreter to translate this code to html and posteriorly insert it into C, so that it can be compiled. The C part stays intact. Inside the wdi source it is not necessary to use prints, every return statement will be used for output (in printf function). The program's output will be clean html code. So, for example a heading 1 tag would be transformed like this: h1 { "Hello, " + toCapital(name) + "!"; } // would become: printf("<h1>Hello, %s!</h1>", toCapital(name)); My main goal is to create an interpreter to translate wdi source to html like this: tag(attributes) {content} = <tag attributes>content</tag> Secondly, html code returned by the interpreter has to be inserted into C code with printfs. Variables and functions that occur inside wdi should also be sorted in order to use them as printf parameters (the case of toCapital(name) in sample source). Here are my flex/bison files: id [a-zA-Z_]([a-zA-Z0-9_])* number [0-9]+ string \".*\" %% {id} { yylval.string = strdup(yytext); return(ID); } {number} { yylval.number = atoi(yytext); return(NUMBER); } {string} { yylval.string = strdup(yytext); return(STRING); } "(" { return(LPAREN); } ")" { return(RPAREN); } "{" { return(LBRACE); } "}" { return(RBRACE); } "=" { return(ASSIGN); } "," { return(COMMA); } ";" { return(SEMICOLON); } \n|\r|\f { /* ignore EOL */ } [ \t]+ { /* ignore whitespace */ } . { /* return(CCODE); Find C source */ } %% %start wdi %token LPAREN RPAREN LBRACE RBRACE ASSIGN COMMA SEMICOLON CCODE QUOTE %union { int number; char *string; } %token <string> ID STRING %token <number> NUMBER %% wdi : /* empty */ | blocks ; blocks : block | blocks block ; block : head SEMICOLON | head body ; head : ID | ID attributes ; attributes : LPAREN RPAREN | LPAREN attribute_list RPAREN ; attribute_list : attribute | attribute COMMA attribute_list ; attribute : key ASSIGN value ; key : ID {$$=$1} ; value : STRING {$$=$1} /*| NUMBER*/ /*| CCODE*/ ; body : LBRACE content RBRACE ; content : /* */ | blocks | STRING SEMICOLON | NUMBER SEMICOLON | CCODE ; %% I am having difficulties on defining a proper grammar for the language, specially in splitting WDI and C code . I just started learning language processing techniques so I need some orientation. Could someone correct my code or give some examples of what is the right way to solve this problem?

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  • Enforce strong type checking in C (type strictness for typedefs)

    - by quinmars
    Is there a way to enforce explicit cast for typedefs of the same type? I've to deal with utf8 and sometimes I get confused with the indices for the character count and the byte count. So it be nice to have some typedefs: typedef unsigned int char_idx_t; typedef unsigned int byte_idx_t; With the addition that you need an explicit cast between them: char_idx_t a = 0; byte_idx_t b; b = a; // compile warning b = (byte_idx_t) a; // ok I know that such a feature doesn't exist in C, but maybe you know a trick or a compiler extension (preferable gcc) that does that. EDIT: I still don't really like the Hungarian notation in general, I couldn't used it for this problem because of project coding conventions, but I used it now in another similar case, where also the types are the same and the meanings are very similar. And I have to admit: it helps. I never would go and declare every integer with a starting "i", but as in Joel's example for overlapping types, it can be life saving.

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  • Compile time float packing/punning

    - by detly
    I'm writing C for the PIC32MX, compiled with Microchip's PIC32 C compiler (based on GCC 3.4). My problem is this: I have some reprogrammable numeric data that is stored either on EEPROM or in the program flash of the chip. This means that when I want to store a float, I have to do some type punning: typedef union { int intval; float floatval; } IntFloat; unsigned int float_as_int(float fval) { IntFloat intf; intf.floatval = fval; return intf.intval; } // Stores an int of data in whatever storage we're using void StoreInt(unsigned int data, unsigned int address); void StoreFPVal(float data, unsigned int address) { StoreInt(float_as_int(data), address); } I also include default values as an array of compile time constants. For (unsigned) integer values this is trivial, I just use the integer literal. For floats, though, I have to use this Python snippet to convert them to their word representation to include them in the array: import struct hex(struct.unpack("I", struct.pack("f", float_value))[0]) ...and so my array of defaults has these indecipherable values like: const unsigned int DEFAULTS[] = { 0x00000001, // Some default integer value, 1 0x3C83126F, // Some default float value, 0.005 } (These actually take the form of X macro constructs, but that doesn't make a difference here.) Commenting is nice, but is there a better way? It's be great to be able to do something like: const unsigned int DEFAULTS[] = { 0x00000001, // Some default integer value, 1 COMPILE_TIME_CONVERT(0.005), // Some default float value, 0.005 } ...but I'm completely at a loss, and I don't even know if such a thing is possible. Notes Obviously "no, it isn't possible" is an acceptable answer if true. I'm not overly concerned about portability, so implementation defined behaviour is fine, undefined behaviour is not (I have the IDB appendix sitting in front of me). As fas as I'm aware, this needs to be a compile time conversion, since DEFAULTS is in the global scope. Please correct me if I'm wrong about this.

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  • Porting - Shared Memory x32 & x64 processes

    - by dpb
    A 32 bit host Windows application setups shared memory (using memory mapped file / CreateFileMapping() API), and then other 32 bit client processes use this shared memory to communicate with each other. I am planning to port the host application to 64 bit platform and once it is ready, I intend that both 32 bit and 64 bit client processes should be able to use the shared memory setup by the main 64 bit host application. The original code written for host x32 application uses "size_t" almost everywhere, since this differs from 4 bytes to 8 bytes as we move from x32 to x64, I am looking for replacing it. I intend to replace "size_t" by "unsigned long long", so that its size will be same on 32 bit & 64 bit. Can you please suggest me better alternative? Also, will the use of "unsigned long long" have performance impact on x32 app .. i guess yes? Research Done - Found very useful articles - a) 20 issue in porting from 32 bit to 64 bit (www.viva64.com) b) No way to restrict/change "size_t" on x64 platform to 4 bytes using compiler flags or any hooks/crooks since it is typedef

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  • can not override showDialog in Activity tab

    - by hornetbzz
    Trying to downgrade my appl from android 2.2 (API 8) down to android 2.1 (API7), I'm facing some issues with dialog boxes. Based on this thread, I'm trying to catch these exceptions but can't override the showDialog method. I turned the Java compiler from 1.5 to 1.6 according to this answer to a similar issue, but no changes, Eclipse still returns : Cannot override the final method from Activity public class MyActivity extends Activity implements SeekBar.OnSeekBarChangeListener { // ... some stuffs @Override // here is the issue public void showDialog(int dialogId) { try { super.showDialog(dialogId); } catch (IllegalArgumentException e) { Log.e(ACTIVITY_TAG, "Error dialog"); } } @Override protected Dialog onCreateDialog(int id) { switch (id) { case DIALOG_ALERT: // Create out AlertDialog Builder builder = new AlertDialog.Builder(this); builder.setMessage(msg); builder.setCancelable(false); builder.setPositiveButton(GOTO_BOOK, new OkOnClickListener()); builder.setNegativeButton(STAY_HERE, new CancelOnClickListener()); AlertDialog dialog = builder.create(); dialog.show(); break; case DIALOG_ONCREATE: // Create out AlertDialog during the "onCreate" method (only "Ok" // button) Builder builder2 = new AlertDialog.Builder(getParent()); builder2.setMessage(msg); builder2.setCancelable(false); builder2.setPositiveButton(GO_BACK, new OkOnClickListener()); AlertDialog dialog2 = builder2.create(); dialog2.show(); break; } return super.onCreateDialog(id); } // ... some stuffs }

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  • Boost::Spirit::Qi autorules -- avoiding repeated copying of AST data structures

    - by phooji
    I've been using Qi and Karma to do some processing on several small languages. Most of the grammars are pretty small (20-40 rules). I've been able to use autorules almost exclusively, so my parse trees consist entirely of variants, structs, and std::vectors. This setup works great for the common case: 1) parse something (Qi), 2) make minor manipulations to the parse tree (visitor), and 3) output something (Karma). However, I'm concerned about what will happen if I want to make complex structural changes to a syntax tree, like moving big subtrees around. Consider the following toy example: A grammar for s-expr-style logical expressions that uses autorules... // Inside grammar class; rule names match struct names... pexpr %= pand | por | var | bconst; pand %= lit("(and ") >> (pexpr % lit(" ")) >> ")"; por %= lit("(or ") >> (pexpr % lit(" ")) >> ")"; pnot %= lit("(not ") >> pexpr >> ")"; ... which leads to parse tree representation that looks like this... struct var { std::string name; }; struct bconst { bool val; }; struct pand; struct por; struct pnot; typedef boost::variant<bconst, var, boost::recursive_wrapper<pand>, boost::recursive_wrapper<por>, boost::recursive_wrapper<pnot> > pexpr; struct pand { std::vector<pexpr> operands; }; struct por { std::vector<pexpr> operands; }; struct pnot { pexpr victim; }; // Many Fusion Macros here Suppose I have a parse tree that looks something like this: pand / ... \ por por / \ / \ var var var var (The ellipsis means 'many more children of similar shape for pand.') Now, suppose that I want negate each of the por nodes, so that the end result is: pand / ... \ pnot pnot | | por por / \ / \ var var var var The direct approach would be, for each por subtree: - create pnot node (copies por in construction); - re-assign the appropriate vector slot in the pand node (copies pnot node and its por subtree). Alternatively, I could construct a separate vector, and then replace (swap) the pand vector wholesale, eliminating a second round of copying. All of this seems cumbersome compared to a pointer-based tree representation, which would allow for the pnot nodes to be inserted without any copying of existing nodes. My question: Is there a way to avoid copy-heavy tree manipulations with autorule-compliant data structures? Should I bite the bullet and just use non-autorules to build a pointer-based AST (e.g., http://boost-spirit.com/home/2010/03/11/s-expressions-and-variants/)?

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  • how avoids deadlock condition

    - by rima
    Hi I try to write a program like a compiler.In this case I must simulate these codes of SQLPL(This one can be just for example).for example in command prompt i wana do these: c:\> sqlplus .... Enter User-Name:(here we must enter username) xxxx Enter password:(same up)yyyyy ... sql>(now i want to send my sql command to shell)prompt "rima"; "rima" [<-output] sql> prompt "xxxx" sql> exit very simple. I try to use this code: ProcessStartInfo psi = new ProcessStartInfo( @"sqlplus"); psi.UseShellExecute = false; psi.CreateNoWindow = true; psi.RedirectStandardInput = true; psi.RedirectStandardOutput = true; //psi.RedirectStandardError = true; Process process = new Process(); process.StartInfo = psi; bool started = process.Start(); if (started) { process.StandardInput.WriteLine("user/password"); process.StandardInput.Flush(); string ret = process.StandardOutput.ReadLine(); // <-- stalls here System.Console.WriteLine("sqlplus says :" + ret + "\"."); } i find out it form here but as if u read this code has problem!DEADLOCK Condition problem! this is my second time i ask my question,every time my knowledge growing,but i cant get how I can solve my problem at last!!! So I kindly kiss your hand,please help me,these process is not clear for me.any one can give me a code that handle my problem?Already i look at all codes,also I try to use ProcessRunner that in my last post some one offer me,but I cant use it also,i receive an error. I hope by first example u find out what i want,and solve the second code problem... thanks I use C# for implemantation

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  • A monkey could do this better - Access to and availability of private member functions in C++

    - by David
    I am wandering the desert of my brain. I'm trying to write something like the following: class MyClass { // Peripherally Related Stuff public: void TakeAnAction(int oneThing, int anotherThing) { switch(oneThing){ case THING_A: TakeThisActionWith(anotherThing); break; //cases THINGS_NOT_A: }; private: void TakeThisActionWith(int thing) { string outcome = new string; outcome = LookUpOutcome(thing); // Do some stuff based on outcome return; } string LookUpOutcome(int key) { string oc = new string; oc = MyPrivateMap[key]; return oc; } map<int, string> MyPrivateMap; Then in the .cc file where I am actually using these things, while compiling the TakeAnAction section, it [CC, the solaris compiler] throws an an error: 'The function LookUpOutcome must have a prototype' and bombs out. In my header file, I have declared 'string LookUpOutcome(int key);' in the private section of the class. I have tried all sorts of variations. I tried to use 'this' for a little while, and it gave me 'Can only use this in non-static member function.' Sadly, I haven't declared anything static and these are all, putatively, member functions. I tried it [on TakeAnAction and LookUp] when I got the error, but I got something like, 'Can't access MyPrivateMap from LookUp'. MyPrivateMap could be made public and I could refer to it directly, I guess, but my sensibility says that is not the right way to go about this [that means that namespace scoped helper functions are out, I think]. I also guess I could just inline the lookup and subsequent other stuff, but my line-o-meter goes on tilt. I'm trying desperately not to kludge it.

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  • Strange Behaviour in Swift: constant defined with LET but behaving like a variable defined with VAR

    - by Sam
    Stuck on the below for a day! Any insight would be greatly appreciated. The constant in the first block match0 behaves as expected. The constant defined in the second block does not behave as nicely in the face of a change to its "source": var str = "+y+z*1.0*sum(A1:A3)" if let range0 = str.rangeOfString("^\\+|^\\-|^\\*|^\\/", options: NSStringCompareOptions.RegularExpressionSearch){ let match0 = str[range0] println(match0) //yields "+" - as expexted str.removeRange(range0) println(match0) //yields "+" - as expected str.removeRange(range0) println(match0) //yields "+" - as expected } if let range1 = str.rangeOfString("^\\+|^\\-|^\\*|^\\/", options: NSStringCompareOptions.RegularExpressionSearch){ let match1 = str[range1] println(match1) //yields "+" as expected str.removeRange(range1) println(match1) //!@#$ OMG!!!!!!!!!!! a constant variable has changed! This prints "z" } The following are the options I can see: match1 has somehow obtained a reference to its source instead of being copied by value [Problem: Strings are value types in Swift] match1 has somehow obtained a closure to its source instead of just being a normal constant/variable? [Problem: sounds like science fiction & then why does match0 behave so well?] Could there be a bug in the Swift compiler? [Problem: Experience has taught me that this is very very very rarely the solution to your problem...but it is still in beta]

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  • Instantiating and starting a Scala Actor in a Map

    - by Bruce Ferguson
    I'm experimenting with a map of actors, and would like to know how to instantiate them and start them in one fell swoop... import scala.actors.Actor import scala.actors.Actor._ import scala.collection.mutable._ abstract class Message case class Update extends Message object Test { val groupings = "group1" :: "group2" :: "group3":: Nil val myActorMap = new HashMap[String,MyActor] def main(args : Array[String]) { groupings.foreach(group => myActorMap += (group -> new MyActor)) myActorMap("group2").start myActorMap("group2") ! Update } } class MyActor extends Actor { def act() { loop { react { case Update => println("Received Update") case _ => println("Ignoring event") } } } } The line: myActorMap("group2").start will grab the second instance, and let me start it, but I would like to be able to do something more like: groupings.foreach(group => myActorMap += (group -> (new MyActor).start)) but no matter how I wrap the new Actor, the compiler complains with something along the lines of: type mismatch; found : scala.actors.Actor required: com.myCompany.test.MyActor or various other complaints. I know it must be something simple to do with anonymous classes, but I can't see it right now. Any suggestions? Thanks in advance!!

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  • Potential g++ template bug?

    - by Evan Teran
    I've encountered some code which I think should compile, but doesn't. So I'm hoping some of the local standards experts here at SO can help :-). I basically have some code which resembles this: #include <iostream> template <class T = int> class A { public: class U { }; public: U f() const { return U(); } }; // test either the work around or the code I want... #ifndef USE_FIX template <class T> bool operator==(const typename A<T>::U &x, int y) { return true; } #else typedef A<int> AI; bool operator==(const AI::U &x, int y) { return true; } #endif int main() { A<int> a; std::cout << (a.f() == 1) << std::endl; } So, to describe what is going on here. I have a class template (A) which has an internal class (U) and at least one member function which can return an instance of that internal class (f()). Then I am attempting to create an operator== function which compares this internal type to some other type (in this case an int, but it doesn't seem to matter). When USE_FIX is not defined I get the following error: test.cc: In function 'int main()': test.cc:27:25: error: no match for 'operator==' in 'a.A<T>::f [with T = int]() == 1' Which seems odd, because I am clearly (I think) defining a templated operator== which should cover this, in fact if I just do a little of the work for the compiler (enable USE_FIX), then I no longer get an error. Unfortunately, the "fix" doesn't work generically, only for a specific instantiation of the template. Is this supposed to work as I expected? Or is this simply not allowed? BTW: if it matters I am using gcc 4.5.2.

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  • VB.NET switching from ADO.NET to LINQ

    - by Cj Anderson
    I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

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  • Adding items to a combo box's internal list programatically.

    - by Andrew
    So, despite Matt's generous explanation in my last question, I still didn't understand and decided to start a new project and use an internal list. - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { codesList = [[NSString alloc] initWithContentsOfFile: @".../.../codelist.txt"]; namesList = [[NSString alloc] initWithContentsOfFile: @".../.../namelist.txt"]; codesListArray = [[NSMutableArray alloc]initWithArray:[codesList componentsSeparatedByString:@"\n"]]; namesListArray = [[NSMutableArray alloc]initWithArray:[namesList componentsSeparatedByString:@"\n"]]; addTheDash = [[NSString alloc]initWithString:@" - "]; flossNames = [[NSMutableArray alloc]init]; [flossNames removeAllObjects]; for (int n=0; n<=[codesListArray count]; n++){ NSMutableString *nameBuilder = [[NSMutableString alloc]initWithFormat:@"%@", [codesListArray objectAtIndex:n]]; [nameBuilder appendString:addTheDash]; [nameBuilder appendString:[namesListArray objectAtIndex:n]]; [comboBoz addItemWithObjectValue:[NSMutableString stringWithString:nameBuilder]]; [nameBuilder release]; } } So this is my latest attempt at this and the list still isn't showing in my combo box. I've tried using the addItemsWithObjectValues outside the for loop along with the suggestions at this question: Is this the right way to add items to NSCombobox in Cocoa ? But still no luck. If you can't tell, I'm trying to combine two strings from the files with a hyphen in between them and then put that new string into the combo box. There are over 400 codes and matching names in the two files, so manually putting them in would be a huge chore, not to mention, I don't see what would be causing this problem. The compiler shows no warnings or errors, and in the IB, I have it set to use the internal list, but when I run it, the list is not populated unless I do it manually. Some things I thought might be causing it: Being in the applicationDidFinishLaunching: method Having the string and array variables declared as instance variables in the header (along with @property and @synth done to them) Messing around with using appendString multiple times with NSMutableArrays Nothing seems to be causing this to me, but maybe someone else will know something I don't. Thanks for the help.

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  • (x86) Assembler Optimization

    - by Pindatjuh
    I'm building a compiler/assembler/linker in Java for the x86-32 (IA32) processor targeting Windows. High-level concepts of a "language" (in essential a Java API for creating executables) are translated into opcodes, which then are wrapped and outputted to a file. The translation process has several phases, one is the translation between languages: the highest-level code is translated into the medium-level code which is then translated into the lowest-level code (probably more than 3 levels). My problem is the following; if I have higher-level code (X and Y) translated to lower-level code (x, y, U and V), then an example of such a translation is, in pseudo-code: x + U(f) // generated by X + V(f) + y // generated by Y (An easy example) where V is the opposite of U (compare with a stack push as U and a pop as V). This needs to be 'optimized' into: x + y (essentially removing the "useless" code) My idea was to use regular expressions. For the above case, it'll be a regular expression looking like this: x:(U(x)+V(x)):null, meaning for all x find U(x) followed by V(x) and replace by null. Imagine more complex regular expressions, for more complex optimizations. This should work on all levels. What do you suggest? What would be a good approach to optimize in these situations?

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  • c incompatible types in assignment, problem with pointers?

    - by Fantastic Fourier
    Hi I'm working with C and I have a question about assigning pointers. struct foo { int _bar; char * _car[MAXINT]; // this is meant to be an array of char * so that it can hold pointers to names of cars } int foofunc (void * arg) { int bar; char * car[MAXINT]; struct foo thing = (struct foo *) arg; bar = arg->_bar; // this works fine car = arg->_car; // this gives compiler errors of incompatible types in assignment } car and _car have same declaration so why am I getting an error about incompatible types? My guess is that it has something to do with them being pointers (because they are pointers to arrays of char *, right?) but I don't see why that is a problem. when i declared char * car; instead of char * car[MAXINT]; it compiles fine. but I don't see how that would be useful to me later when I need to access certain info using index, it would be very annoying to access that info later. in fact, I'm not even sure if I am going about the right way, maybe there is a better way to store a bunch of strings instead of using array of char *?

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  • how to templatize partial template specializations?

    - by Kyle
    I'm not even sure what title to give this question; hopefully the code will demonstrate what I'm trying to do: #include <string> #include <list> using namespace std; template<typename A> class Alpha { public: A m_alpha_a; }; template<typename B> class Bravo { public: B m_bravo_b; }; template<> class Alpha<string> { public: string m_alpha_string; }; template<typename B> template<> class Alpha<Bravo<B> > { public: Bravo<B> m_bravo_class; // Line A }; int main() { Alpha<int> alpha_int; alpha_int.m_alpha_a= 4; Alpha<string> alpha_string; alpha_string.m_alpha_string = "hi"; Alpha<Bravo<int> > alpha_bravo_int; alpha_bravo_int.m_bravo_class.m_bravo_b = 9; }; I want to write a specialization for Alpha<A> when A is of any type Bravo<B>, but the compiler says invalid explicit specialization before ‘’ token enclosing class templates are not explicitly specialized (Referring to // Line A.) What's the correct syntax to do what I want?

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  • Why are my Flex resource bundles not being loaded?

    - by Chris R
    I have an Actionscript module in the flex source folder filterModules, which is one of two additional source folders in my project (the main source folder is reports, but I'm not dealing with anything in there right now). Here's the MXML content that references the resources. ... This array is assigned to the dataProvider field of a ComboBox. It's not bound using the bindings, presumably for reasons that made sense to the original developer, and it'd be nontrivial to change the class to make that happen. I additionally have a resource property file in a folder resources/en_US and I have the source folder resources/{locale} in the project source settings. My additional compiler options are -locale en_US. The resource property file is resources/en_US/labels.properties (All paths are relative to the flash builder project root) and contains (amongst other things) these keys: metric.q3 = Overall Satisfaction metric.q5 = Personnel metric.q9a = Issue Resolution metric.q42 = Visit Duration Sat metric.q34 = Visit Duration I have written some FlexUnit tests that run in my local Flash Player that exercise these resources -- they check that every label is represented in the metrics array, for example, so I know that the resource file is loaded when run locally. However, when I copy the module .swf file over to my server, the combo box to which the array is assigned is empty. I copy the .swf like so, if it matters: rsync -rlDv --inplace -T /tmp ~/projects/flex_reports/bin-debug/rankingFilter.swf HOSTNAME:WEBROOT/flashPath/ Why is this? I am not able to debug the remote module because our surrounding site sets up a lot of context and makes some database calls to determine which module to load. I'm hoping to get some pointers on why resource bundles might not show up. I'd understand it if the array was present with wrong labels, but the array is instead completely empty, which is pretty odd.

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  • How do I return a message if $_GET is null or does not match any database entries?

    - by CT
    I am working on designing an IT Asset database. Here I am working on a page used to view details on a specific asset determined by an asset id. Here I grab $id from $_GET["id"]; When $id is null, the page does not load. When $id does not match any entry within the database, the page loads but no asset table is printed. In both these cases, I would like to display a message like "There is no database entry for that Asset ID" How would this be handled? Thank you. <?php /* * View Asset * */ # include functions script include "functions.php"; $id = $_GET["id"]; ConnectDB(); $type = GetAssetType($id); ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="style.css" /> <title>Wagman IT Asset</title> </head> <body> <div id="page"> <div id="header"> <img src="images/logo.png" /> </div> </div> <div id="content"> <div id="container"> <div id="main"> <div id="menu"> <ul> <table width="100%" border="0"> <tr> <td width="15%"></td> <td width="30%%"><li><a href="index.php">Search Assets</a></li></td> <td width="30%"><li><a href="addAsset.php">Add Asset</a></li></td> <td width="25%"></td> </tr> </table> </ul> </div> <div id="text"> <ul> <li> <h1>View Asset</h1> </li> </ul> <br /> <?php switch ($type){ case "Server": $result = QueryServer($id); $ServerArray = GetServerData($result); PrintServerTable($ServerArray); break; case "Desktop"; break; case "Laptop"; break; } ?> </div> </div> </div> <div class="clear"></div> <div id="footer" align="center"> <p>&nbsp;</p> </div> </div> <div id="tagline"> Wagman Construction - Bridging Generations since 1902 </div> </body> </html>

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  • Diamond problem in C++

    - by Jack
    I know the diamond problem. I am using gcc compiler. I have some scenarios I need explanation about. 1) class A{ public: virtual void eat(){cout<<"A eat\n";} }; class B:public A{ public: void eat(){ cout<<"B eat\n";}}; class C:public A{ public: void eat(){ cout<<"C eat\n";}}; class D:public B,C{ public: void eat(){ cout<<"D eat\n";}}; int main() { A * a = new D(); a->eat(); getch(); return 0; } Why doesn't this work? 2) class A{ public: void eat(){cout<<"A eat\n";} }; class B:virtual public A{ public: void eat(){ cout<<"B eat\n";}}; class C:virtual public A{ public: void eat(){ cout<<"C eat\n";}}; class D: public B,C{ public: void eat(){ cout<<"D eat\n";}}; int main() { A * a = new D(); a->eat(); getch(); return 0; } When I do this what happens in the background. How does the ambiguity get removed. Is the concept of vtables involved here?

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  • Why does one of these statements compile in Scala but not the other?

    - by Jeff
    (Note: I'm using Scala 2.7.7 here, not 2.8). I'm doing something pretty simple -- creating a map based on the values in a simple, 2-column CSV file -- and I've completed it easily enough, but I'm perplexed at why my first attempt didn't compile. Here's the code: // Returns Iterator[String] private def getLines = Source.fromFile(csvFilePath).getLines // This doesn't compile: def mapping: Map[String,String] = { Map(getLines map { line: String => val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() }.toList:_*) } // This DOES compile def mapping: Map[String,String] = { def strPair(line: String): (String,String) = { val pairArr = line.split(",") pairArr(0) -> pairArr(1).trim() } Map(getLines.map( strPair(_) ).toList:_*) } The compiler error is CsvReader.scala:16: error: value toList is not a member of (St ring) = (java.lang.String, java.lang.String) [scalac] possible cause: maybe a semicolon is missing before `value toList'? [scalac] }.toList:_*) [scalac] ^ [scalac] one error found So what gives? They seem like they should be equivalent to me, apart from the explicit function definition (vs. anonymous in the nonworking example) and () vs. {}. If I replace the curly braces with parentheses in the nonworking example, the error is "';' expected, but 'val' found." But if I remove the local variable definition and split the string twice AND use parens instead of curly braces, it compiles. Can someone explain this difference to me, preferably with a link to Scala docs explaining the difference between parens and curly braces when used to surround method arguments?

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  • How can I create an executable to run on a certain processor architecture (instead of certain OS)?

    - by CrazyJugglerDrummer
    So I take my C++ program in Visual studio, compile, and it'll spit out a nice little EXE file. But EXEs will only run on windows, and I hear a lot about how C/C++ compiles into assembly language, which is runs directly on a processor. The EXE runs with the help of windows, or I could have a program that makes an executable that runs on a mac. But aren't I compiling C++ code into assembly language, which is processor specific? My Insights: I'm guessing I'm probably not. I know there's an Intel C++ compiler, so would it make processor-specific assembly code? EXEs run on windows, so they advantage of tons of things already set up, from graphics packages to the massive .NET framework. A processor-specific executable would be literally starting from scratch, with just the instruction set of the processor. Would this executable be a file-type? We could be running windows and open it, but then would control switch to processor only? I assume this executable would be something like an operating system, in that it would have to be run before anything else was booted up, and have only the processor instruction set to "use".

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  • Function parameters evaluation order: is undefined behaviour if we pass reference?

    - by bolov
    This is undefined behaviour: void feedMeValue(int x, int a) { cout << x << " " << a << endl; } int main() { int a = 2; int &ra = a; feedMeValue(ra = 3, a); return 0; } because depending on what parameter gets evaluated first we could call (3, 2) or (3, 3). However this: void feedMeReference(int x, int const &ref) { cout << x << " " << ref << endl; } int main() { int a = 2; int &ra = a; feedMeReference(ra = 3, a); return 0; } will always output 3 3 since the second parameter is a reference and all parameters have been evaluated before the function call, so even if the second parameter is evaluated before of after ra = 3, the function received a reference to a wich will have a value of 2 or 3 at the time of the evaluation, but will always have the value 3 at the time of the function call. Is the second example UB? It is important to know because the compiler is free to do anything if he detects undefined behaviour, even if I know it would always yield the same results. *Note: I think that feedMeReference(a = 3, a) is the exact same situation as feedMeReference(ra = 3, a). However it seems not everybody agrees, in the addition to having 2 completely different answers.

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