composition

How to compose functions of varying arity using Lodash flow?

由 喜欢而已 提交于 2019-11-27 06:28:16
问题 I want to do some function composition. I know already this: If f3(x) shall be the same as f1(f2(x)) then f3 = _.flowRight(f1,f2); If f3(x,y) shall be the same as f1(x, f2(y)) then …? (The use case is the composition of node.js/express middleware functions.) 回答1: In the following images, I use {_} as a placeholder for a value. Think of it as a hole in the code where we pass something in. Ok let's imagine what your function would have to do... Does this seems like a generic transformation? ie,

Ensuring embedded structs implement interface without introducing ambiguity

由 可紊 提交于 2019-11-27 05:53:29
问题 I'm trying to clean up my code base by doing a better job defining interfaces and using embedded structs to reuse functionality. In my case I have many entity types that can be linked to various objects. I want to define interfaces that capture the requirements and structs that implement the interfaces which can then be embedded into the entities. // All entities implement this interface type Entity interface { Identifier() Type() } // Interface for entities that can link Foos type FooLinker

Aggregation vs Composition vs Association vs Direct Association

由 别说谁变了你拦得住时间么 提交于 2019-11-27 04:57:33
问题 I am reviewing my knowledge in object-oriented programming. Under the relationship between classes topic, I have encountered some relationships which are a bit ambiguous to me. I know dependency "uses-a" and inheritance "is-a" but I'm a bit unfamiliar with Aggregation, Composition, Association and Direct Association; also, which of them is "has-a" relationship. Some use Aggregation interchangeably with Association. What is Direct Association? Also, what is Composition? In UML diagrams, the

Canvas image masking / overlapping

由 别说谁变了你拦得住时间么 提交于 2019-11-27 02:51:42
In my project i have to implement one different color image on the other same size and pattern image using canvas and images are not in round or rectangle shapes. That all are in waves shape and it will apply on a single main background image for showing multiple graphics on every onclick function. Overlapped image should be change in another selected color. My question Is there any way with using canvas from that we can change the image color which is draw by canvas or we need to use different images always and apply with CSS/jQuery. I read about canvas image masking and overlapping. But cant

Should I use inheritance or composition?

由 一个人想着一个人 提交于 2019-11-27 01:42:11
问题 I would like to keep this one short. I build a HouseA that has two rooms, say BedRoom and StudyRoom , both deriving from a base class called Room . BedRoom and StudyRoom have a same parent called House . Also, any room in a house can access any other rooms only through the parent. If BedRoom has to access any attribute of StudyRoom , it has to go only via House (i.e. parent) and vice-versa. HouseA ISA House HouseA HAS BedRoom and StudyRoom. BedRoom ISA Room StudyRoom ISA Room Now the Problem:

“Is a” vs “Has a” : which one is better?

由 痴心易碎 提交于 2019-11-27 00:39:33
问题 Portfolio A → Fund 1 Portfolio A → Fund 2 Portfolio A → Fund 3 I couldn't frame my sentence without not using is/has. But between 1 & 2, 1) has a: class PortfolioA { List<Fund> obj; } 2) is a: class PortfolioA : List<Fund> { } which one do you think is better from the point of extensibility, usability? I can still access my funds either way, albeit with a small syntactical change. 回答1: I vote with the other folks who say HAS-A is better in this case. You ask in a comment: when I say that a

How to compose `not` with a function of arbitrary arity?

由 馋奶兔 提交于 2019-11-27 00:26:56
When I have some function of type like f :: (Ord a) => a -> a -> Bool f a b = a > b I should like make function which wrap this function with not. e.g. make function like this g :: (Ord a) => a -> a -> Bool g a b = not $ f a b I can make combinator like n f = (\a -> \b -> not $ f a b) But I don't know how. *Main> let n f = (\a -> \b -> not $ f a b) n :: (t -> t1 -> Bool) -> t -> t1 -> Bool Main> :t n f n f :: (Ord t) => t -> t -> Bool *Main> let g = n f g :: () -> () -> Bool What am I doing wrong? And bonus question how I can do this for function with more and lest parameters e.g. t -> Bool t

Haskell composition (.) vs F#'s pipe forward operator (|>)

由 蹲街弑〆低调 提交于 2019-11-26 23:56:54
问题 In F#, use of the the pipe-forward operator, |> , is pretty common. However, in Haskell I've only ever seen function composition, (.) , being used. I understand that they are related, but is there a language reason that pipe-forward isn't used in Haskell or is it something else? 回答1: I am being a little speculative... Culture : I think |> is an important operator in the F# "culture", and perhaps similarly with . for Haskell. F# has a function composition operator << but I think the F#

Python: Inheritance versus Composition

由 ◇◆丶佛笑我妖孽 提交于 2019-11-26 23:03:19
问题 I am working with two classes in Python, one of which should be allowed to have any number objects from another class as children while keeping an inventory of these children as an attribute. Inheritance seemed like the obvious choice for this parent<>child situation but instead what I have arrived at is an example of composition. Here is the simplified code: class Parent(): def __init__(self,firstname,lastname): self.firstname = firstname self.lastname = lastname self.kids = [] def havechild

How to use Facelets composition with files from another context

由 柔情痞子 提交于 2019-11-26 23:00:46
I have an application that use composition (for page templates). But we think in create a web-application (war) to host all templates shared by all applications in the same host of all applications. How I can include a template from another context? At this time I use import from http request. But it's sounds like bad. <ui:composition template="http://localhost:8080/templates/layout/foo.xhtml"> I'm using JBoss Seam 2.x with JSF 1. BalusC Note that this is to be done differently in JSF 2.x Facelets, see this answer for detail. This is possible with a custom Facelets resource resolver. I would
订阅 composition