callback

问题 Still new in GTK, now trying to work on event-driven programming and stuck in weird situation: there is no problem to send scalar items to callback function, but then it comes to sending struct to it, still receiving the error with no idea what's wrong. Sample "stub" code is: #include <gtk/gtk.h> #include <stdlib.h> void messageup(); void exiting(); struct data{ char *message; GtkWidget *window; }; int main (int argc, char *argv[]) { GtkBuilder *builder; GtkWidget *window; GtkWidget

问题 I'm dynamically creating a number of div elements (rows). Every row will have the same basic format, only text changes. As the row structure is complex, I'm trying to load a "basic" div from a static html file, and then once loaded, tweak some of the attributes with each row's params. (Something like Android's xml-defined adapters). I'm using jQuery and jQuery Mobile. I call this function several times (once per row). On each call I pass as parameters a params object, containing the data for

问题 I am trying to activate callback function as the user type in to the tkinter entry box. According to effbot.org, You can use the trace method to attach “observer” callbacks to the variable. The callback is called whenever the contents change: So i tired this, import Tkinter as tk window2=tk.Tk() anf_frame1=tk.Frame(window2,bg='white',relief='groove',bd=0,width=1190,height=175) anf_frame1.place(x=10,y=50) def myfunction(*args): print 'pass' stringvar1 = tk.StringVar(anf_frame1) stringvar1

问题 I'm using Python 2.7, if that matters. Here is a code I wrote for fun: def p(): root = Tk() def cmd(event): print int(slider.get()) slider = Scale(root, orient = "horizontal", from_ = 0, to = 100, command = cmd, state = "disabled") def enable(): slider.config(state = "active") b = Button(root, text = "Enable slider", command = enable) b.grid() slider.grid(row = 1) root.mainloop() For this code, I'm wondering why the command for Scale requires an event, but that for Button does not. It seems

问题 I'm using Python 2.7, if that matters. Here is a code I wrote for fun: def p(): root = Tk() def cmd(event): print int(slider.get()) slider = Scale(root, orient = "horizontal", from_ = 0, to = 100, command = cmd, state = "disabled") def enable(): slider.config(state = "active") b = Button(root, text = "Enable slider", command = enable) b.grid() slider.grid(row = 1) root.mainloop() For this code, I'm wondering why the command for Scale requires an event, but that for Button does not. It seems

问题 Using React's useCallback hook is essentially just a wrapper around useMemo specialized for functions to avoid constantly creating new function instances within components' props. My question comes from when you need to pass an argued to the callback created from the memoization. For instance, a callback created like so... const Button: React.FunctionComponent = props => { const onClick = React.useCallback(() => alert('Clicked!'), []) return <button onClick={onClick}>{props.children}</button>

问题 def parse(self, response): for sel in response.xpath('//tbody/tr'): item = HeroItem() item['hclass'] = response.request.url.split("/")[8].split('-')[-1] item['server'] = response.request.url.split('/')[2].split('.')[0] item['hardcore'] = len(response.request.url.split("/")[8].split('-')) == 3 item['seasonal'] = response.request.url.split("/")[6] == 'season' item['rank'] = sel.xpath('td[@class="cell-Rank"]/text()').extract()[0].strip() item['battle_tag'] = sel.xpath('td[@class="cell-BattleTag"

问题 Im new to hook and so is react,Ive been watching some tutorials lately,I saw Ben awad's video for dynamic forms and I tried replicating it.There he used a callback inside the useState updater function which seems new to me.He used link setPeople(currentPeople => {}) What is the argument currentPeople come from and why its used,Can you someone please explain,Thanks in advance! import { useState } from "react"; import "./App.css"; import { generate } from "shortid"; interface Person { id:

问题 I am using PostgreSql as database and Rails 3.1.3 and ruby 1.9.3 I have 3 models. Activity ActivityObject ActivityObjectActivity They are related this way. Activity has_many :activity_object_activities,:dependent => :destroy has_many :activity_objects, :through => :activity_object_activities after_destroy :do_something_on_activity_object_related ActivityObject has_many :activity_object_activities, :dependent => :destroy has_many :activities, :through => :activity_object_activities

问题 I am using PostgreSql as database and Rails 3.1.3 and ruby 1.9.3 I have 3 models. Activity ActivityObject ActivityObjectActivity They are related this way. Activity has_many :activity_object_activities,:dependent => :destroy has_many :activity_objects, :through => :activity_object_activities after_destroy :do_something_on_activity_object_related ActivityObject has_many :activity_object_activities, :dependent => :destroy has_many :activities, :through => :activity_object_activities