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问题 I'm trying to create and use a cache for a server JSON response. something like volley response caching does. https://stackoverflow.com/a/32022946/1993001 in Android I am using DIO for network operations. 回答1: You can you create your own cache with Interceptors on top of Dio requests. You can create in on your own: import 'package:dio/dio.dart'; class CacheInterceptor extends Interceptor { CacheInterceptor(); var _cache = new Map<Uri, Response>(); @override onRequest(RequestOptions options)

问题 I'm overriding the init method in my form andthis is now returning an error 'TransactionForm' object has no attribute '_errors' . I would expect this to work because I've included super in my init , however perhaps I don't understand how to use this correctly. An explanation would be appreciated. What do I need to do to get form.errors working? Full traceback Traceback: File "C:\Program Files\Python36\lib\site-packages\django\core\handlers\exception.py" in inner 35. response = get_response

问题 I'm overriding the init method in my form andthis is now returning an error 'TransactionForm' object has no attribute '_errors' . I would expect this to work because I've included super in my init , however perhaps I don't understand how to use this correctly. An explanation would be appreciated. What do I need to do to get form.errors working? Full traceback Traceback: File "C:\Program Files\Python36\lib\site-packages\django\core\handlers\exception.py" in inner 35. response = get_response

问题 I'm trying to make a C++ class using the Code::Blocks IDE and there is a field called "Guard block." I've done a search and haven't been able to find any useful information. What is this field for? Thanks. 回答1: Guard blocks are used to protect against the inclusion of a header file multiple times by the same compilation unit (c++ file). They look something like this: // Foo.h #ifndef INCLUDE_FILE_NAME_HERE_H_ #define INCLUDE_FILE_NAME_HERE_H_ class Foo { }; #endif If you include the same file

问题 I'm quite new to Espresso on Android and I am running into the following problem: I want Espresso to perform a longclick(or something..) on a button, and while the button is kept pressed down, I want to check the state of a different View. In (more or less) pseudocode: onView(withId(button_id)).perform(pressButtonDown()); onView(withId(textBox_id)).check(matches(withText("Button is pressed"))); onView(withId(button_id)).perform(releaseButton()); I tried writing 2 custom Taps, PRESS and

问题 I want to search in text for the less than sign < between dollar signs like $x<y$ and replace it by $x < y$ . I am using mathjax and less than sign causes some problems in rendering Mathjax.(See here: http://docs.mathjax.org/en/latest/tex.html#tex-and-latex-in-html-documents). I tried $text = preg_replace("/\$(.*?)(<)(.*?)\$/","/\$$1 < $3\$/",$text) but I am not sure if this is a good solution. I am new to programming:) Thank you for your help. 回答1: I edited my previous answer - now try this:

问题 I have a component, that takes a balance prop, and this balance prop can change over time. I then have a React Final Form to send a transaction, with usual fields amount to send, receiver... And in my validate , I just check that the user has enough balance to send the transaction. However, if my balance changes when the user is inputting something, then the whole form resets. How would you only reset part of the form state? See this codesandbox for an example: https://codesandbox.io/s

问题 In the effort to better learn React, TypeScript, and Context / Hooks, I'm making a simple Todo app. However, the code needed to make the context feels cumbersome. For example, if I want to change what a Todo has, I have to change it in three places (ITodo interface, default context value, default state value). If I want to pass down something new, I have to do that in three places (TodoContext, TodoContext's default value, and value=). Is there a better way to not have to write so much code?

问题 I have an editor in which I want to check that selected text will not contain some words. If it contains those particular words, then I need to deselect the selection made by user. Is there any way to do that in JTextPane ? 回答1: Text selection is temporaray and contiguous. You can't unselect some text in the middle of a larger string of selected text. Maybe you are talking about highlighting. Check out the API for getHighlighter(). You can add/remove highlights and specify the start/end

问题 I have a code uses Cairo and Pango to create an image : #include<stdio.h> #include<cairo.h> #include<pango/pangocairo.h> #define IMAGE_WIDTH 650 #define IMAGE_HEIGHT 150 #define TEXT "HELLO WORLD" #define FONT "MizuFontAlphabet Normal 40" /* * $ gcc $(pkg-config pangocairo cairo --cflags --libs) file.c */ int main(int argc , char** argv) { cairo_surface_t *surface; cairo_t *cr; PangoLayout *layout; PangoFontDescription *desc; PangoRectangle extents; surface = cairo_image_surface_create(CAIRO