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  • Python/YACC Lexer: Token priority?

    - by Rosarch
    I'm trying to use reserved words in my grammar: reserved = { 'if' : 'IF', 'then' : 'THEN', 'else' : 'ELSE', 'while' : 'WHILE', } tokens = [ 'DEPT_CODE', 'COURSE_NUMBER', 'OR_CONJ', 'ID', ] + list(reserved.values()) t_DEPT_CODE = r'[A-Z]{2,}' t_COURSE_NUMBER = r'[0-9]{4}' t_OR_CONJ = r'or' t_ignore = ' \t' def t_ID(t): r'[a-zA-Z_][a-zA-Z_0-9]*' if t.value in reserved.values(): t.type = reserved[t.value] return t return None However, the t_ID rule somehow swallows up DEPT_CODE and OR_CONJ. How can I get around this? I'd like those two to take higher precedence than the reserved words.

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  • Which style is preferable when writing this boolean expression?

    - by Jeppe Stig Nielsen
    I know this question is to some degree a matter of taste. I admit this is not something I don't understand, it's just something I want to hear others' opinion about. I need to write a method that takes two arguments, a boolean and a string. The boolean is in a sense (which will be obvious shortly) redundant, but it is part of a specification that the method must take in both arguments, and must raise an exception with a specific message text if the boolean has the "wrong" value. The bool must be true if and only if the string is not null or empty. So here are some different styles to write (hopefully!) the same thing. Which one do you find is the most readable, and compliant with good coding practice? // option A: Use two if, repeat throw statement and duplication of message string public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name)) throw new SomeException("..."); if (!useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option B: Long expression but using only && and || public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name) || !useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option C: With == operator between booleans public void SomeMethod(bool useName, string name) { if (useName == string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option D1: With XOR operator public void SomeMethod(bool useName, string name) { if (!(useName ^ string.IsNullOrEmpty(name))) throw new SomeException("..."); // rest of method } // option D2: With XOR operator public void SomeMethod(bool useName, string name) { if (useName ^ !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } Of course you're welcome to suggest other possibilities too. Message text "..." would be something like "If 'useName' is true a name must be given, and if 'useName' is false no name is allowed".

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  • Checking for uppercase/lowercase/numbers with Jquery

    - by user1725794
    Either I'm being really retarded here or its just the lack of sleep but why doesn't this work? If I use the "or" operator it works for each separate test but as soon as it change it to the "and" operator it stops working. I'm trying to test the password input of a form to see if its contains lowercase, uppercase and at least 1 number of symbol. I'm having a lot of trouble with this so help would be lovely, here is the code I have. var upperCase= new RegExp('[^A-Z]'); var lowerCase= new RegExp('[^a-z]'); var numbers = new RegExp('[^0-9]'); if(!$(this).val().match(upperCase) && !$(this).val().match(lowerCase) && !$(this).val().match(numbers)) { $("#passwordErrorMsg").html("Your password must be between 6 and 20 characters. It must contain a mixture of upper and lower case letters, and at least one number or symbol."); } else { $("#passwordErrorMsg").html("OK") }

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  • NHibernate - define where condition

    - by t.kehl
    Hi. In my application the user can defines search-conditions. He can choose a column, set an operator (equals, like, greater than, less or equal than, etc.) and give in the value. After the user clicks on a button and the application should do a search on the database with the condition. I use NHibernate and ask me now, what is the efficientest way to do this with NHibernate. Should I create a query with it like (Column=Name, Operator=Like, Value=%John%) var a = session.CreateCriteria<Customer>(); a.Add(Restrictions.Like("Name", "%John%")); return a.List<Customer>(); Or should I do this with HQL: var q = session.CreateQuery("from Customer where " + where); return q.List<Customer >(); Or is there a more bether solution? Thanks for your help. Best Regards, Thomas

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  • help in compare validate in c#

    - by scatman
    i have 2 textboxes that i am filling with StartDate, and Endate. i want to use the compareValidator to make sure that the StartDate is less that the EndDate. i used this: <asp:CompareValidator ID="Comp" ControlToValidate="txtStartDate" ControlToCompare="txtEndDate" Operator="LessThan" Type="Date" runat="server" Display="dynamic" Text="Failed!" /> the validator is always giving me Failed no matter what the dates are. if startdateendate or vise versa, Failed appears. i am using (MM/dd/yyyy) format in the textboxes. EDIT: ok i solved the problem. if anyone interested here is the new comparevalidator: <asp:CompareValidator ID="Comp" ControlToValidate="txtEndDate" ControlToCompare="txtStartDate" Operator="GreaterThan" Type="Date" runat="server" Display="dynamic" Text="Failed!" />

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  • Python scope problems only when _assigning_ to a variable

    - by wallacoloo
    So I'm having a very strange error right now. I found where it happens, and here's the simplest code that can reproduce it. def parse_ops(str_in): c_type = "operator" def c_dat_check_type(t): print c_type #c_type = t c_dat_check_type("number") >>> parse_ops("12+a*2.5") If you run it as-is, it prints "operator". But if you uncomment that line, it gives an error: Traceback (most recent call last): File "<pyshell#212>", line 1, in <module> parse_ops("12+a*2.5") File "<pyshell#211>", line 7, in parse_ops c_dat_check_type("number") File "<pyshell#211>", line 4, in c_dat_check_type print c_type UnboundLocalError: local variable 'c_type' referenced before assignment Notice the error occurs on the line that worked just fine before. Any ideas what causes this and how I can fix this? I'm using Python 2.6.1.

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  • How to get this to compile?

    - by ShaChris23
    I have this code which compiles and works as expected: class Right {}; class Left { public: Left& operator = (Right const&) { //... Do something ... return *this; } }; int main() { Right right; Left left; // Assign individual object -- this works left = right; } But now, this one surprises me, I thought the template would work itself out since I already provided the = operator() to the Left class. int main() { ... std::list<Right> rightLst; std::list<Left> leftLst; // Assign a list of objects -- this doesn't compile leftLst = rightLst; } What can I do so that I could convert the rightLst to leftLst conversion in a single line?

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  • distinguishing a string with flex

    - by haluk
    Hi, I need to tokenize some strings which will be splitted of according to operators like = and !=. I was successful using regex until the string has != operator. In my case, string was seperated into two parts, which is expected but ! mark is in the left side even it is part of given operator. Therefore, I believe that regex is not suitable for it and I want to benefit from lex. Since I do not have enough knowledge and experience with lex, I am not sure whether it fits my work or not. Basically, I am trying to do replace the right hand side of the operators with actual values from other data. Do you people think that can it be helpful for my case? Thanks.

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  • C++ enumeration

    - by asli
    Hi,my question is about enumeration,my codes are : #include<iostream> using namespace std; int main() { enum bolumler {programcilik,donanim,muhasebe,motor,buro} bolum; bolum = donanim; cout << bolum << endl; bolum += 2; // bolum=motor cout << bolum; return 0; } The output should be 1 3 but according to these codes the error is: error C2676: binary '+=' : 'enum main::bolumler' does not define this operator or a conversion to a type acceptable to the predefined operator Error executing cl.exe. 111.obj - 1 error(s), 0 warning(s) Can you help me ?The other question is what can I do if I want to see the output like that "muhasebe"?

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  • Maps with a nested vector

    - by wawiti
    For some reason the compiler won't let me retrieve the vector of integers from the map that I've created, I want to be able to overwrite this vector with a new vector. The error the compiler gives me is ridiculous. Thanks for your help!! The compiler didn't like this part of my code: line_num = miss_words[word_1]; Error: [Wawiti@localhost Lab2]$ g++ -g -Wall *.cpp -o lab2 main.cpp: In function ‘int main(int, char**)’: main.cpp:156:49: error: no match for ‘operator=’ in ‘miss_words.std::map<_Key, _Tp, _Compare, _Alloc>::operator[]<std::basic_string<char>, std::vector<int>, std::less<std::basic_string<char> >, std::allocator<std::pair<const std::basic_string<char>, std::vector<int> > > >((*(const key_type*)(& word_1))) = line_num.std::vector<_Tp, _Alloc>::push_back<int, std::allocator<int> >((*(const value_type*)(& line)))’ main.cpp:156:49: note: candidate is: In file included from /usr/lib/gcc/x86_64-redhat->linux/4.7.2/../../../../include/c++/4.7.2vector:70:0, from header.h:19, from main.cpp:15: /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/bits/vector.tcc:161:5: note: std::vector<_Tp, _Alloc>& std::vector<_Tp, _Alloc>::operator=(const std::vector<_Tp, _Alloc>&) [with _Tp = int; _Alloc = std::allocator<int>] /usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../include/c++/4.7.2/bits/vector.tcc:161:5: note: no known conversion for argument 1 from ‘void’ to ‘const std::vector<int>&’ CODE: map<string, vector<int> > miss_words; // Creates a map for misspelled words string word_1; // String for word; string sentence; // To store each line; vector<int> line_num; // To store line numbers ifstream file; // Opens file to be spell checked file.open(argv[2]); int line = 1; while(getline(file, sentence)) // Reads in file sentence by sentence { sentence=remove_punct(sentence); // Removes punctuation from sentence stringstream pars_sentence; // Creates stringstream pars_sentence << sentence; // Places sentence in a stringstream while(pars_sentence >> word_1) // Picks apart sentence word by word { if(dictionary.find(word_1)==dictionary.end()) { line_num = miss_words[word_1]; //Compiler doesn't like this miss_words[word_1] = line_num.push_back(line); } } line++; // Increments line marker }

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  • Response, Result, Reply, which is best?

    - by Robert Gould
    I'm refactoring some client-server code and it uses the terms Response, Result & Reply for the same thing (an answer from the server). And although its not really that important it's become hard to guess which word to use while writing new code, so I'd like to unify the three terms into one and do the appropriate refactoring, but I'm not sure which word is the "best", if there is such a thing. Any suggestions based on precedence and standards towards naming for this case?

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  • Would this constructor be acceptable practice?

    - by Robb
    Let's assume I have a c++ class that have properly implemented a copy constructor and an overloaded = operator. By properly implemented I mean they are working and perform a deep copy: Class1::Class1(const Class1 &class1) { // Perform copy } Class1& Class1::operator=(const Class1 *class1) { // perform copy return *this; } Now lets say I have this constructor as well: Class1::Class1(Class1 *class1) { *this = *class1; } My question is would the above constructor be acceptable practice? This is code that i've inherited and maintaining.

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  • UrlRewriteFilter Direct to https

    - by adi
    I am using UrlRewriteFilter to redirect to SSL. I am running Glassfishv2. My rule looks something like this now. It's in my urlrewrite.xml in WEB-INF of my war folder. Is there any other glassfish setting that needs to be set? <rule> <condition name="host" operator="notequal">https://abc.def.com</condition> <condition name="host" operator="notequal">^$</condition> <from>^/(.*)</from> <to type="permanent-redirect" last="true">https://abc.def.com/ghi/$1</to> </rule> But FF keeps saying that the URL redirect rule is in a way that it will never complete. I am not exactly sure whats happening here. any ideas?

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  • C++ Why is the copy constructor implicitly called?

    - by ShaChris23
    Why is the Child class's copy constructor called in the code below? I mean, it automatically converts Base to Child via the Child copy constructor. The code below compiles, but shouldn't it not compile since I haven't provided bool Child::operator!=(Base const&)? class Base { }; class Child : public Base { public: Child() {} Child(Base const& base_) : Base(base_) { std::cout <<"should never called!"; } bool operator!=(Child const&) { return true; } }; void main() { Base base; Child child; if(child != base) std::cout << "not equal"; else std::cout << "equal"; }

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  • typeof === "undefined" vs. != null

    - by Thor Thurn
    I often see JavaScript code which checks for undefined parameters etc. this way: if (typeof input !== "undefined") { // do stuff } This seems kind of wasteful, since it involves both a type lookup and a string comparison, not to mention its verbosity. It's needed because 'undefined' could be renamed, though. My question is: How is that code any better than this approach: if (input != null) { // do stuff } As far as I know, you can't redefine null, so it's not going to break unexpectedly. And, because of the type-coercion of the != operator, this checks for both undefined and null... which is often exactly what you want (e.g. for optional function parameters). Yet this form does not seem widespread, and it even causes JSLint to yell at you for using the evil != operator. Why is this considered bad style?

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  • C# XOR on two byte variables will not compile without a cast

    - by Ash
    Why does the following raise a compile time error: 'Cannot implicitly convert type 'int' to 'byte': byte a = 25; byte b = 60; byte c = a ^ b; This would make sense if I were using an arithmentic operator because the result of a + b could be larger than can be stored in a single byte. However applying this to the XOR operator is pointless. XOR here it a bitwise operation that can never overflow a byte. using a cast around both operands works: byte c = (byte)(a ^ b);

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  • Description Class for Navigation Links not working

    - by Carmel
    My problem is with my navigation links. I've created a class for the links so that the link color is different from the typical links throughout. The problem is that the color defined in a:visited is taking precedence over the color defined in a:link. I've tried everything and can't work this out. Any suggestions?

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  • non-scalar type requested

    - by lego69
    can somebody please help me with an error conversion from `A' to non-scalar type `B' requested I have class A and derived from it B, but I have problems with these rows: A a(1); A *pb = new B(a); B b = *pb; //here I have an error thanks in advance for any help class A { protected: int player; public: A(int initPlayer = 0); A(const A&); A& operator=(const A&); virtual ~A(){}; virtual void foo(); void foo() const; operator int(); }; class B: public A { public: B(int initPlayer): A(initPlayer){}; ~B(){}; virtual void foo(); };

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  • C# Type Casting at Runtimefor Array.SetValue

    - by sprocketonline
    I'm trying to create an array using reflection, and insert values into it. I'm trying to do this for many different types so would like a createAndFillArray function capable of this : Type t1 = typeof(A); Type t2 = typeof(B); double exampleA = 22.5; int exampleB = 43; Array arrA = createAndFillArray(t1, exampleA); Array arrB = createAndFillArray(t2, exampleB); private Array createAndFillArray(Type t, object val){ Array arr = Array.CreateInstance( t, 1); //length 1 in this example only, real-world is of variable length. arr.SetValue( val, 0 ); //this causes the following error: "System.InvalidCastException : Object cannot be stored in an array of this type." return arr; } with the class A being as follows: public class A{ public A(){} private double val; public double Value{ get{ return val; } set{ this.val = value; } } public static implicit operator A(double d){ A a = new A(); a.Value = d; return a; } } and class B being very similar, but with int: public class B{ public B(){} private double val; public double Value{ get{ return val; } set{ this.val = value; } } public static implicit operator B(double d){ B b = new B(); b.Value = d; return b; } } I hoped that the implicit operator would have ensured that the double be converted to class A, or the int to class B, and the error avoided; but this is obviously not so. The above is used in a custom deserialization class, which takes data from a custom data format and fills in the corresponding .Net object properties. I'm doing this via reflection and at runtime, so I think both are unavoidable. I'm targeting the C# 2.0 framework. I've dozens, if not hundreds, of classes similar to A and B, so would prefer to find a solution which improved on the createAndFillArray method rather than a solution which altered these classes.

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  • Using a class with const data members in a vector

    - by Max
    Given a class like this: class Foo { const int a; }; Is it possible to put that class in a vector? When I try, my compiler tells me it can't use the default assignment operator. I try to write my own, but googling around tells me that it's impossible to write an assignment operator for a class with const data members. One post I found said that "if you made [the data member] const that means you don't want assignment to happen in the first place." This makes sense. I've written a class with const data members, and I never intended on using assignment on it, but apparently I need assignment to put it in a vector. Is there a way around this that still preserves const-correctness?

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