dynamic

问题 Let's say I have this: dynamic foo = new Foobar(); And I have this: public class Foobar : DynamicObject { } The question is, is it possible to override members of DynamicObject so that this code: string name = new Foobar().Name Does not throw an Exception at run-time? I want to return default for name 's if Name is not a member. Possible? What do I need to override? 回答1: Override TryGetMember (and TrySetMember). Classes derived from the DynamicObject class can override this method to specify

问题 Let's say I have this: dynamic foo = new Foobar(); And I have this: public class Foobar : DynamicObject { } The question is, is it possible to override members of DynamicObject so that this code: string name = new Foobar().Name Does not throw an Exception at run-time? I want to return default for name 's if Name is not a member. Possible? What do I need to override? 回答1: Override TryGetMember (and TrySetMember). Classes derived from the DynamicObject class can override this method to specify

问题 Please refer to the code and comments below: vector<int> v1(10); cin>>v1[0]; // allowed cin>>v1[1]; // allowed // now I want v1 to hold 20 elements so the following is possible: cin>>v1[15]>>v[19]; // how to resize the v1 so index 10 to 19 is available. 回答1: You simply need to resize the vector before adding the new values: v1.resize(20); 回答2: You could use resize like this: v1.resize(20); 回答3: If you want to read as many values from cin as are available, you can use an istream_iterator

问题 I have a project with these modules: app bookingfeature (instant enabled) map (not instant) app contains some common code and resources and a starting activity with some logic to route the app to the correct destination, based on whether it's running as instant or not. bookingfeature contains an activity and some fragments that I want to deploy with the instant app. map contains the rest of the app (work in progress to split this into more modules) Everything works fine if I deploy it like

问题 I'm trying to build some thing like a video gallery which you can select a video to show up by clicking on its thumbnail. Now I'm at phase of loading appropriate subtitles for the chosen video. Thanks to google I understand that videojs has a method to help me called addTextTrack() but unfortunately there is not a good sample or documentation for it. After all I tried to find its parameters and behavior via reading the video.dev.js codes. but as I understand this method has just three params

问题 I'm trying to build some thing like a video gallery which you can select a video to show up by clicking on its thumbnail. Now I'm at phase of loading appropriate subtitles for the chosen video. Thanks to google I understand that videojs has a method to help me called addTextTrack() but unfortunately there is not a good sample or documentation for it. After all I tried to find its parameters and behavior via reading the video.dev.js codes. but as I understand this method has just three params

问题 So I'm using scrapy to scrape a data from Amazon books section. But somehow I got to know that it has some dynamic data. I want to know how dynamic data can be extracted from the website. Here's something I've tried so far: import scrapy from ..items import AmazonsItem class AmazonSpiderSpider(scrapy.Spider): name = 'amazon_spider' start_urls = ['https://www.amazon.in/s?k=agatha+christie+books&crid=3MWRDVZPSKVG0&sprefix=agatha%2Caps%2C269&ref=nb_sb_ss_i_1_6'] def parse(self, response): items

问题 I am trying to ask the user to select the type of item in the first dropdown and then select from its corresponding available colours in the second dropdown. However, when after I have selected a colour (i.e. white) and now want to switch to another item that does not have this colour, an error is thrown: "There should be exactly one item with [DropdownButton]'s value: white. \nEither zero or 2 or more [DropdownMenuItem]s were detected with the same value" Please help, I have already tried to

问题 Here's the setup: I have an Open Source project called Massive and I'm slinging around dynamics as a way of creating SQL on the fly, and dynamic result sets on the fly. To do the database end of things I'm using System.Data.Common and the ProviderFactory stuff. Here's a sample that works just fine (it's static so you can run in a Console): static DbCommand CreateCommand(string sql) { return DbProviderFactories.GetFactory("System.Data.SqlClient") .CreateCommand(); } static DbConnection

问题 Is it possible to convert .a files to .dylib files in Mac osx? I currently have libraryname.a and it can't seem to include it in my program as only .dylib libraries are included. Is there also a command that shows static libraries used in a program via mac osx terminal? 回答1: Yes, this is possible. To convert foo.a into libfoo.dylib , try this command: clang -fpic -shared -Wl,-all_load foo.a -o libfoo.dylib On Linux, here's the equivalent command using gcc : gcc -fpic -shared -Wl,-whole