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  • Multiple Inheritence with same Base Classes in Python

    - by Jordan Reiter
    I'm trying to wrap my head around multiple inheritance in python. Suppose I have the following base class: class Structure(object): def build(self, *args): print "I am building a structure!" self.components = args And let's say I have two classes that inherit from it: class House(Structure): def build(self, *args): print "I am building a house!" super(House, self).build(*args) class School(Structure): def build(self, type="Elementary", *args): print "I am building a school!" super(School, self).build(*args) Finally, a create a class that uses multiple inheritance: class SchoolHouse(School, House): def build(self, *args): print "I am building a schoolhouse!" super(School, self).build(*args) Then, I create a SchoolHouse object and run build on it: >>> sh = SchoolHouse() >>> sh.build("roof", "walls") I am building a schoolhouse! I am building a house! I am building a structure! So I'm wondering -- what happened to the School class? Is there any way to get Python to run both somehow? I'm wondering specifically because there are a fair number of Django packages out there that provide custom Managers for models. But there doesn't appear to be a way to combine them without writing one or the other of the Managers as inheriting from the other one. It'd be nice to just import both and use both somehow, but looks like it can't be done? Also I guess it'd just help to be pointed to a good primer on multiple inheritance in Python. I have done some work with Mixins before and really enjoy using them. I guess I just wonder if there is any elegant way to combine functionality from two different classes when they inherit from the same base class.

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  • Virtualbox, merging snapshots and base disk

    - by Henrik
    Hi, I have a virtual machine with about 30 snapshots in branches. The current development path is 22 snapshots plus the base disk. The amount of files is seemingly having an impact now on IO and the dev laptop I'm using (don't know if it is host disk performance issues with the 140GB total size over a lot of fragments, or just the fact that it is hitting sectors distributed across a lot of files). I would like to merge the current development branch of snapshots together with the base disk, but I am unsure if the following command would produce the correct outcome. I am not able to boot this disk after the procedure completes (5-6 hours). vboxmanage clonehd "C:\VPC-Storage\.VirtualBox\Machines\CRM\Snapshots\{245b27ac-e658-470a-b978-8e62137c33b1}.vhd" "E:\crm-20100624.vhd" --format VHD --type normal Could anyone confirm if this is the correct approach or not?

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  • c# multi inheritance

    - by user326839
    So ive got a base class which requires a Socket: class Sock { public Socket s; public Sock(Socket s) { this.s = s; } public virtual void Process(byte[] data) { } ... } then ive got another class. if a new socket gets accepted a new instance of this class will be created: class Game : Sock { public Random Random = new Random(); public Timerr Timers; public Test Test; public Game(Socket s) : base(s) { } public static void ReceiveNewSocket(object s) { Game Client = new Game((Socket)s); Client.Start(); } public override void Process(byte[] buf) { Timers = new Timerr(s); Test = new Test(s); Test.T(); } } in the Sock class ive got a virtual function that gets overwritten by the Game class.(Process function) in this function im calling a function from the Test Class(Test+ Timerr Class: class Test : Game { public Test(Socket s) : base(s) { } public void T() { Console.WriteLine(Random.Next(0, 10)); Timers.Start(); } } class Timerr : Game { public Timerr(Socket s) : base(s) { } public void Start() { Console.WriteLine("test"); } } ) So in the Process function im calling a function in Test. And in this function(T) i need to call a function from the Timerr Class.But the problem is its always NULL , although the constructor is called in Process. And e.g. the Random Class can be called, i guess its because its defined with the constructor.: public Random Random = new Random(); and thats why the other classes(without a constructor): public Timerr Timers; public Test Test; are always null in the inherited class Test.But its essentiel that i call other Methods of other classes in this function.How could i solve that?

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  • overriding enumeration base type using pragma or code change

    - by vprajan
    Problem: I am using a big C/C++ code base which works on gcc & visual studio compilers where enum base type is by default 32-bit(integer type). This code also has lots of inline + embedded assembly which treats enum as integer type and enum data is used as 32-bit flags in many cases. When compiled this code with realview ARM RVCT 2.2 compiler, we started getting many issues since realview compiler decides enum base type automatically based on the value an enum is set to. http://www.keil.com/support/man/docs/armccref/armccref_Babjddhe.htm For example, Consider the below enum, enum Scale { TimesOne, //0 TimesTwo, //1 TimesFour, //2 TimesEight, //3 }; This enum is used as a 32-bit flag. but compiler optimizes it to unsigned char type for this enum. Using --enum_is_int compiler option is not a good solution for our case, since it converts all the enum's to 32-bit which will break interaction with any external code compiled without --enum_is_int. This is warning i found in RVCT compilers & Library guide, The --enum_is_int option is not recommended for general use and is not required for ISO-compatible source. Code compiled with this option is not compliant with the ABI for the ARM Architecture (base standard) [BSABI], and incorrect use might result in a failure at runtime. This option is not supported by the C++ libraries. Question How to convert all enum's base type (by hand-coded changes) to use 32-bit without affecting value ordering? enum Scale { TimesOne=0x00000000, TimesTwo, // 0x00000001 TimesFour, // 0x00000002 TimesEight, //0x00000003 }; I tried the above change. But compiler optimizes this also for our bad luck. :( There is some syntax in .NET like enum Scale: int Is this a ISO C++ standard and ARM compiler lacks it? There is no #pragma to control this enum in ARM RVCT 2.2 compiler. Is there any hidden pragma available ?

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  • Rails & ActiveRecord: Appending methods to models that inherit from ActiveRecord::Base

    - by PlankTon
    I have a standard ActiveRecord model with the following: class MyModel < ActiveRecord::Base custom_method :first_field, :second_field end At the moment, that custom_method is picked up by a module sent to ActiveRecord::Base. The functionality basically works, but of course, it attaches itself to every model class, not just MyModel. So if I have MyModel and MyOtherModel in the same action, it'll assume MyOtherModel has custom_method :first_field, :second_field as well. So, my question is: How do I attach a method (eg: def custom_method(*args)) to every class that inherits from ActiveRecord::Base, but not by attaching it to ActiveRecord::Base itself? Any ideas appreciated.

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  • Multi-base conversion - using all combinations for URL shortener

    - by Guffa
    I am making an URL shortener, and I am struggling with the optimal way of encoding a number (id) into a character string. I am using the characters 0-9,A-Z,a-z so it will basically be a base-62 encoding. That is pretty basic, but it doesn't make use of all possible codes. The codes that it would produce would be: 0, 1, ... y, z, 10, 11, ... zy, zz, 100, 101, ... Notice that the codes 00 to 0z is not used, the same for 000 to 0zz, and so on. I would like to use all the codes, like this: 0, 1, ... y, z, 00, 01, ... zy, zz, 000, 001, ... It would be some combination of base-62 and base-63, with different bases depending on the position... Using base-62 is easy, for example: create procedure tiny_GetCode @UrlId int as set nocount on declare @Code varchar(10) set @Code = '' while (@UrlId > 0 or len(@Code) = 0) begin set @Code = substring('0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz', @UrlId % 62 + 1, 1) + @Code set @UrlId = @UrlId / 62 end select @Code But I haven't yet managed to make a multi-base conversion out of it, to make use of all the codes.

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  • Python: Why can't I use `super` on a class?

    - by cool-RR
    Why can't I use super to get a method of a class's superclass? Example: Python 3.1.3 >>> class A(object): ... def my_method(self): pass >>> class B(A): ... def my_method(self): pass >>> super(B).my_method Traceback (most recent call last): File "<pyshell#2>", line 1, in <module> super(B).my_method AttributeError: 'super' object has no attribute 'my_method' (Of course this is a trivial case where I could just do A.my_method, but I needed this for a case of diamond-inheritance.) According to super's documentation, it seems like what I want should be possible. This is super's documentation: (Emphasis mine) super() - same as super(__class__, <first argument>) super(type) - unbound super object super(type, obj) - bound super object; requires isinstance(obj, type) super(type, type2) - bound super object; requires issubclass(type2, type) [non-relevant examples redacted]

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  • Castle Windsor - Resolving a generic implementation to a base type

    - by arootbeer
    I'm trying to use Windsor as a factory to provide specification implementations based on subtypes of XAbstractBase (an abstract message base class in my case). I have code like the following: public abstract class XAbstractBase { } public class YImplementation : XAbstractBase { } public class ZImplementation : XAbstractBase { } public interface ISpecification<T> where T : XAbstractBase { bool PredicateLogic(); } public class DefaultSpecificationImplementation : ISpecification<XAbstractBase> { public bool PredicateLogic() { return true; } } public class SpecificSpecificationImplementation : ISpecification<YImplementation> { public bool PredicateLogic() { /*do real work*/ } } My component registration code looks like this: container.Register( AllTypes.FromAssembly(Assembly.GetExecutingAssembly()) .BasedOn(typeof(ISpecification<>)) .WithService.FirstInterface() ) This works fine when I try to resolve ISpecification<YImplementation>; it correctly resolves SpecificSpecificationImplementation. However, when I try to resolve ISpecification<ZImplementation> Windsor throws an exception: "No component for supporting the service ISpecification'1[ZImplementation, AssemblyInfo...] was found" Does Windsor support resolving generic implementations down to base classes if no more specific implementation is registered?

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  • Which should be created first ER Diagram OR Class Diagram?

    - by isthatacode
    The very first step i created a DFD. Then i moved on to create a Class Diagram. And while doing that i felt that i should create the ER diagram first. As there were many details which could not be captured in a Class diagram. So, my question should i create ERD first OR Class Diagrams ? your valuable inputs are appreciated guys!!! thanks for reading

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  • extend base.html problem

    - by momo
    I'm getting the following error: Template error In template /home/mo/python/django/templates/yoga/index.html, error at line 1 Caught TemplateDoesNotExist while rendering: base.html 1 {% extends "base.html" %} 2 3 {% block main %} 4 <p>{{ page.title }}</p> 5 <p>{{ page.info}}</p> 6 <a href="method/">Method</a> 7 {% endblock %} 8 this is my base.html file, which is located at the same place as index.html <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <div style="width:50%; marginleft:25%;"> {% block main %}{% endblock %} </div> what exactly is going on here? should the base.html file be located somewhere else?

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  • How do I create a list or set object in a class in Python?

    - by Az
    For my project, the role of the Lecturer (defined as a class) is to offer projects to students. Project itself is also a class. I have some global dictionaries, keyed by the unique numeric id's for lecturers and projects that map to objects. Thus for the "lecturers" dictionary (currently): lecturer[id] = Lecturer(lec_name, lec_id, max_students) I'm currently reading in a white-space delimited text file that has been generated from a database. I have no direct access to the database so I haven't much say on how the file is formatted. Here's a fictionalised snippet that shows how the text file is structured. Please pardon the cheesiness. 0001 001 "Miyamoto, S." "Even Newer Super Mario Bros" 0002 001 "Miyamoto, S." "Legend of Zelda: Skies of Hyrule" 0003 002 "Molyneux, P." "Project Milo" 0004 002 "Molyneux, P." "Fable III" 0005 003 "Blow, J." "Ponytail" The structure of each line is basically proj_id, lec_id, lec_name, proj_name. Now, I'm currently reading the relevant data into the relevant objects. Thus, proj_id is stored in class Project whereas lec_name is a class Lecturer object, et al. The Lecturer and Project classes are not currently related. However, as I read in each line from the text file, for that line, I wish to read in the project offered by the lecturer into the Lecturer class; I'm already reading the proj_id into the Project class. I'd like to create an object in Lecturer called offered_proj which should be a set or list of the projects offered by that lecturer. Thus whenever, for a line, I read in a new project under the same lec_id, offered_proj will be updated with that project. If I wanted to get display a list of projects offered by a lecturer I'd ideally just want to use print lecturers[lec_id].offered_proj. My Python isn't great and I'd appreciate it if someone could show me a way to do that. I'm not sure if it's better as a set or a list, as well. Update After the advice from Alex Martelli and Oddthinking I went back and made some changes and tried to print the results. Here's the code snippet: for line in csv_file: proj_id = int(line[0]) lec_id = int(line[1]) lec_name = line[2] proj_name = line[3] projects[proj_id] = Project(proj_id, proj_name) lecturers[lec_id] = Lecturer(lec_id, lec_name) if lec_id in lecturers.keys(): lecturers[lec_id].offered_proj.add(proj_id) print lec_id, lecturers[lec_id].offered_proj The print lecturers[lec_id].offered_proj line prints the following output: 001 set([0001]) 001 set([0002]) 002 set([0003]) 002 set([0004]) 003 set([0005]) It basically feels like the set is being over-written or somesuch. So if I try to print for a specific lecturer print lec_id, lecturers[001].offered_proj all I get is the last the proj_id that has been read in.

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  • An algorithm for converting a base-10 number to a base-N number.

    - by roja
    Guys, I am looking for a way to convert a base-10 number into a base-N number where N can be large. Specifically i am looking at converting to base-85 and back again. Does anyone know a simple algorithm to perform the conversion? Ideally it would provide something like: to_radix(83992, 85) - [11, 53, 12] Any ideas are appreciated! Roja

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  • What am I not getting about this abstract class implementation?

    - by Schnapple
    PREFACE: I'm relatively inexperienced in C++ so this very well could be a Day 1 n00b question. I'm working on something whose long term goal is to be portable across multiple operating systems. I have the following files: Utilities.h #include <string> class Utilities { public: Utilities() { }; virtual ~Utilities() { }; virtual std::string ParseString(std::string const& RawString) = 0; }; UtilitiesWin.h (for the Windows class/implementation) #include <string> #include "Utilities.h" class UtilitiesWin : public Utilities { public: UtilitiesWin() { }; virtual ~UtilitiesWin() { }; virtual std::string ParseString(std::string const& RawString); }; UtilitiesWin.cpp #include <string> #include "UtilitiesWin.h" std::string UtilitiesWin::ParseString(std::string const& RawString) { // Magic happens here! // I'll put in a line of code to make it seem valid return ""; } So then elsewhere in my code I have this #include <string> #include "Utilities.h" void SomeProgram::SomeMethod() { Utilities *u = new Utilities(); StringData = u->ParseString(StringData); // StringData defined elsewhere } The compiler (Visual Studio 2008) is dying on the instance declaration c:\somepath\somecode.cpp(3) : error C2259: 'Utilities' : cannot instantiate abstract class due to following members: 'std::string Utilities::ParseString(const std::string &)' : is abstract c:\somepath\utilities.h(9) : see declaration of 'Utilities::ParseString' So in this case what I'm wanting to do is use the abstract class (Utilities) like an interface and have it know to go to the implemented version (UtilitiesWin). Obviously I'm doing something wrong but I'm not sure what. It occurs to me as I'm writing this that there's probably a crucial connection between the UtilitiesWin implementation of the Utilities abstract class that I've missed, but I'm not sure where. I mean, the following works #include <string> #include "UtilitiesWin.h" void SomeProgram::SomeMethod() { Utilities *u = new UtilitiesWin(); StringData = u->ParseString(StringData); // StringData defined elsewhere } but it means I'd have to conditionally go through the different versions later (i.e., UtilitiesMac(), UtilitiesLinux(), etc.) What have I missed here?

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  • How do I run jQuery form validation by class?

    - by joshcomley
    Hi there, I've been using the jQuery form validator, but I can't seem to figure out how to trigger it by class. Take this example: $("#myform").validate({ rules: { field: { required: true, date: true } } }); Where field it is expecting the name of the particular input. But, what if I have the following: <input class="date".... /> How can I tell the validator to validate all inputs with a "date" class as a date?

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  • Uiimport does not save variable to base workspace

    - by Tim
    I tried using uiimport to load a file to the base workspace.....It worked first time....but after trying again after a while...I wasnt seeing the variable in the base work space. I used the default variable name which is given by 'uiimport". This was the command I used: uiimport(filename) And two variables where created by default..."data" and "textdata"(which is the header)....but now when i run it is no longer saved in the base workspace I do not want to assign a variable to the uiimport like so... K = uiimport(filename) assignin(base,'green',K) I do not want to do that because My dataset has a text header and the data itself, and doing this would assign both "textdata" and "data" to "green" variable How would I be able to get the dimensions of ONLY the "data" in green and how would I pass only "data"(which is in the green variable in the workspace.."rmbr"...the green variable holds both "data" and "textdata") to another function. I was able to do all this when the uiimport automatically saved the variables in the base workspace....but somehow now it doesn't. I would appreciate any help or tips on this matter

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  • Python Introspection: How to get varnames of class methods?

    - by daccle
    I want to get the names of the keyword arguments of the methods of a class. I think I understood how to get the names of the methods and how to get the variable names of a specific method, but I don't get how to combine these: class A(object): def A1(self, test1=None): self.test1 = test1 def A2(self, test2=None): self.test2 = test2 def A3(self): pass def A4(self, test4=None, test5=None): self.test4 = test4 self.test5 = test5 a = A() # to get the names of the methods: for methodname in a.__class__.__dict__.keys(): print methodname # to get the variable names of a specific method: for varname in a.A1.__func__.__code__.co_varnames: print varname # I want to have something like this: for function in class: print function.name for varname in function: print varname # desired output: A1 self test1 A2 self test2 A3 self A4 self test4 test5

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  • Operator== in derived class never gets called.

    - by Robin Welch
    Can someone please put me out of my misery with this? I'm trying to figure out why a derived operator== never gets called in a loop. To simplify the example, here's my Base and Derived class: class Base { // ... snipped bool operator==( const Base& other ) const { return name_ == other.name_; } }; class Derived : public Base { // ... snipped bool operator==( const Derived& other ) const { return ( static_cast<const Base&>( *this ) == static_cast<const Base&>( other ) ? age_ == other.age_ : false ); }; Now when I instantiate and compare like this ... Derived p1("Sarah", 42); Derived p2("Sarah", 42); bool z = ( p1 == p2 ); ... all is fine. Here the operator== from Derived gets called, but when I loop over a list, comparing items in a list of pointers to Base objects ... list<Base*> coll; coll.push_back( new Base("fred") ); coll.push_back( new Derived("sarah", 42) ); // ... snipped // Get two items from the list. Base& obj1 = **itr; Base& obj2 = **itr2; cout << obj1.asString() << " " << ( ( obj1 == obj2 ) ? "==" : "!=" ) << " " << obj2.asString() << endl; Here asString() (which is virtual and not shown here for brevity) works fine, but obj1 == obj2 always calls the Base operator== even if the two objects are Derived. I know I'm going to kick myself when I find out what's wrong, but if someone could let me down gently it would be much appreciated.

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  • Java: Embedded Data Base

    - by Dmitry
    Hello! I want to create a desctop application with an embedded data base. Data base is JavaDB(Derby). I have connected a jar file derby.jar to my project. The problem is I don't understand how to register a driver to use this data base. It is said that I should use Class.forName("org.apache.derby.jdbc.EmbeddedDriver") But what if that was another data base and its driver was not in a java standart package? As you can see I'm confused with this. I want to know, how to use my connected derby.jar, how to work with its jdbc driver and how to create tables in a specified directory. Please, give as detailed answer, as you can. (I'm a dummy in this =)) )

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  • Is it good to subclass a class only to separate some functional parts?

    - by prostynick
    Suppose we have abstract class A (all examples in C#) public abstract class A { private Foo foo; public A() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //a lot of other stuff... } But we are able to split it into two classes A and B: public abstract class A { public A() { } //a lot of stuff... } public abstract class B : A { private Foo foo; public B() : base() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //nothing else or just some overrides of A stuff } That's good, but we are 99.99% sure, that no one will ever subclass A, because functionality in B is very important. Is it still good to have two separate classes only to split some code into two parts and to separate functional elements?

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  • which should be drawn first , class or sequence diagram?

    - by m0j1
    hi , I've had this discussion with my professor at college about UML diagrams . hi believes that sequence diagrams should be drawn before getting to class diagrams . but I think the opposite . I think after finishing the usecase diagram , the next diagram should be class diagram and after that we should get to sequence diagram . Rational rose requires us to use the classes in sequence diagram, which are already in class diagram . can anyone help me with this? thanks

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  • Differences between a conceptual UML class diagram and an ERD?

    - by Adam
    If I create a conceptual class diagram such that each class captures 'name' and 'attributes' but not 'operations', have I not basically created what would be otherwise considered an ERD? I'm trying to gain an understanding of what the differences are between creating a conceptual class diagram as I have described versus calling it a ERD? If these are still two different animals, can somebody please explain what the differences are?

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  • Meaning of the "Unloading class" messages

    - by elec
    Anyone can explain why the lines below appear in the output console at runtime ? (one possible answer would be full permGen, but this can be ruled out since the program only uses 24MB out of the max100MB available in PermGen) [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor28] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor14] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor4] [Unloading class sun.reflect.GeneratedMethodAccessor5] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor38] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor36] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor22] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor8] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor39] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor16] [Unloading class sun.reflect.GeneratedSerializationConstructorAccessor2] [Unloading class sun.reflect.GeneratedConstructorAccessor1] The program runs with the following params: -Xmx160M -XX:MaxPermSize=96M -XX:PermSize=96M -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+PrintGCTaskTimeStamps -XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -verbose:gc -Xloggc:/logs/gc.log There's plenty of space in the heap and in permGen.

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  • Accessing a namespace containing .base in its name from F#

    - by emaster70
    As the title says, I'm trying to use a class declared in a namespace which contains "base" in its name. Think of a situation like the following: open Foo.base.Bar In C# I'd just use @ before base but F# seems to ignore that and to think that @ is the infix operator used for list concatenation. Since the namespace belongs to a third-party library which I cannot modify, is there a way I can still access it from F#?

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