concept

问题 I am new guy to Demandware and I am switching from Magento to Demandware. Demandware is not opensource I am not getting proper tutorials, stuff to understand the concepts of it. I am from Magento so I know the Magento MVC structure. But in Demandware we have different concepts like pipelines, pipelets, ISML scripts, ECMA script, DW scripts etc. I want to know the MVC pattern of Demandware. How it works and what are the basic concept I need to concentrate? 回答1: I would suggest to request a

问题 I am a noob to Scala so please don't negative vote. class MyClass extends AnyRef class MySubClass extends MyClass val af0: (Seq[_]) => Boolean = (s) ⇒ { s eq null } val f4: (MySubClass) => Boolean = (s) => { s eq null } val af2: (List[_]) => Boolean = af0 //(Line 1) val f7: MyClass => Boolean = f4 //(Line 2) Why line (1) compiles and line (2) does not? To me they both are same as Sequence is subtype of List. How to make it work? like in case of Line 1? https://docs.scala-lang.org/tutorials

问题 This question already has an answer here : What's with the integer cache maintained by the interpreter? (1 answer) Closed 5 years ago . Two individually created mutable list have different ids. Python SHELL: (mutable) >>> mylist = ['spam', 'eggs'] >>> yourlist = ['spam', 'eggs'] >>> id(mylist), id(yourlist) (49624456, 48910408) While two individually created immutable strings have similar ids. Python SHELL: (immutable) >>> a = 10 >>> b = 10 >>> id(a), id(b) (507099072, 507099072) Is a and b

问题 I designed a shopping cart solution for a client. For one of their items (candy, for example), they have a certain quantity they can sell for each type. I deduct from the quantity available after items have been purchased. The candy shopping flow is as follow: Select (add to cart) candy on candy catalog page Go to Cart page to review items to be purchased Go to checkout page (billing information + list of items to be purchased with price total details) Pertinent Situation: Customer A select 9

问题 Developers of hypersonic promise increase of performance? But I'm afraid problems with administrating and other aspects of using hsqlDB. Are anybody using this in production? Is it good idea? 回答1: Many companies are using HSQL in production. Among those not on the list, a certain well-known (though not necessarily well liked) company that makes an antivirus product (whose name rhymes with "Horton") is using HSQL-based software for their update server management. I know because I wrote it :-)

问题 This is not programming language specific. I just need to understand how can I estimate the time needed for a process to complete ? Such as unzipping file for example or burning a CD ? What are the factors that enhance the accuracy of this calculatio ? Some examples in any programming language will help of course. 回答1: Record the actual times taken and relevant factors; estimate future times based the averages of past runs with in similar situations. In most cases it will never be all that

问题 Looking at the possible implementation of the same_as concept at https://en.cppreference.com/w/cpp/concepts/same_as i noticed something strange is happening. namespace detail { template< class T, class U > concept SameHelper = std::is_same_v<T, U>; } template< class T, class U > concept same_as = detail::SameHelper<T, U> && detail::SameHelper<U, T>; The first question is why a SameHelper concept is nedded? The second is why same_as checks if T is the same as U and U the same as T ? Isn't it

问题 In short: Is there a way I can feed a General templated class with something that only represent an enum type? Something like: template <typename T> struct General {}; struct EnumSpecific : General<any_enum_type> {}; <int> is too much / does not work in my case. My specific case: A templated Holder class handles any kind of data in a generic way. An abstract General class implements specific algorithms relying on the Holder s' behaviour. Template specifications of General (like IntSpecific ,

问题 I have a problem grasping the OOP concept when it comes to creating objects during runtime. All the educational code that I have looked into yet defines specific variables e.g. 'Bob' and assigns them to a new object instance. Bob = Person() What I have trouble understanding now is how I would design a model that creates a new object during runtime? I'm aware that my phrasing is probably faulty since all objects are generated during runtime but what I mean is that if I were to start my

问题 So, I had an argument with my professor earlier defending that NULL is not a pointer, but he kept on insisting that it is because there is such a thing as NULL pointer. So, here I am now a little bit confused if NULL is really a pointer or not I already tried search over the internet but couldn't find any answer, so my last resort is here 回答1: In C, NULL is a macro that expands to a null pointer constant. 7.19p3 The macros are NULL which expands to an implementation-defined null pointer