option

问题 I am having trouble with the following: let safeDiv x y = match (x,y) with | (_, Some 0) -> None | (Some xx, Some yy) -> Some (xx/yy) | _ -> None When I go to run this simple function in the interactive window of Visual Studio like so: safeDiv 4 2 I get the following error... This expression was expected to have type int option but here has type int. Could it be I'm meant to use safeDiv Some(4) Some(2) ? This doesn't work either... 回答1: Ok, this is overkill but I actually did something

问题 I'm back with another one -_-. currently my page has buttons to change the color of my Philip's hue lights -- but I want it to be a dropdown that will change as I change the option. Here's what the current buttons look like: <button class="lightbuttontall" onclick="lightcolor(1,colorred);">Light 1 red</button> <button class="lightbuttontall" onclick="lightcolor(2,colorred);">Light 2 red</button> <button class="lightbuttontall" onclick="lightcolor(3,colorred);">Light 3 red</button> </p> <p

问题 Is there a way to avoid having to wrap a potentially null result inside another option when mapping from an option. option.flatMap(arg => Option(arg.somePotentiallyNullValue)) Eg something like option.optionMap(arg => arg.somePotentiallyNullValue ) I just have a lot of Java code in our codebase that means forever wrapping the results of maps in further Option calls. 回答1: What about implicit conversion from nullable type to Option ? Declare this somewhere in scope: implicit def toOption[T](x:

问题 What is the difference between passing two arguments vs passing one argument? val option1 = Option(String,String) and val option2 = Option(String) 回答1: When you write something like Option(1, 2) , the compiler first desugars this to Option.apply(1, 2) , and then when it sees that the Option companion object doesn't have an apply method that takes two arguments, it automatically converts the arguments into a tuple: scala> Option(1, 2) res0: Option[(Int, Int)] = Some((1,2)) It would do

问题 I've activity that i want an option menu to be displayed on. But, i want the option menu to be displayed all the time the activity is displayed. I don't want my users to click (select) the menu button to display it. I want it to be there all the time. How can i do it? thanks 回答1: Activity.openOptionsMenu() . From a design standpoint, I have to agree with Mayra. Wrong approach to begin with. 回答2: If you want options to appear at the bottom of the screen always, don't use the options menu. Just

问题 I have the following code: <div> <% TaxonomicTypeFeed ttf = new TaxonomicTypeFeed(); ArrayList<String> tmp = ttf.getTypes(); System.out.println("Going to print"); for (int i=0; i < tmp.size(); i++) { System.out.println(tmp.get(i)); } %> <form> <select> <% Iterator<String> i = tmp.iterator(); while (i.hasNext()) { String str = i.next(); %> <option value="<%str.toString();%>"><%str.toString();%> </option> <%}%> </select> </form> </div> It creates a dropdown list fine, however there is no text.

问题 The font between the <option> tags cannot be changed with CSS in FireFox. (It can be done, using normal CSS statements, in Chrome.) I can change the font for the <select> part of the statement using CSS, so that the selected option appears in my desired font, but the text between the <option> tags in the dropdown list are always in FireFox's default font. This is important because I want to use a monospace font in the option tags. Can I gain control over style of the font in the <option> tag

问题 I'm trying to let the user select the file encoding when they load or save a file in C# and VS2008. Notepad's dialog boxes have an encoding drop down option at the bottom. There is a way to do it as described in here: http://www.codeproject.com/KB/cs/getsavefilename.aspx. However, I'm wondering if there is any easier way to do this. Windows must have this dialog built-in somewhere, isn't it? 回答1: The dialog that is built in is the standard File Open dialog provided by the Win32 API. This

问题 In my select box options, each option having three words.Now I want apply fixed widths for each word of the option so that the all options will come as i required for example My options are as follows : 1, aaaaa bbbbb ccccccccc 2, aaaaaaaa bbbbbbb cccc 3, aaaaaa bbbbb cccc but i want to display these options in the dropdown as 1, aaaaa bbbbb ccccccccc 2, aaaaaaaa bbbbbbb cccc 3, aaaaaa bbbbb cccc help me if anyone know how to do this 回答1: you can use div and CSS style .See this sample that i

问题 When working with Java from Scala, we have to account for null. HttpServletRequest getters (getAttribute, getHeader, etc.) for example, all potentially return null. I know I can manually do a case/match or map operation on each call to an HttpServletRequest method, but that's a bit tedious. Also, method calls like request.getHeader("Accept-Encoding") are a mouthful. I came up with an enrichment to handle both issues: class Servlet_Request_Provides_NullSafe_Getters (r: HttpServletRequest) {