constants

问题 I am getting a warning saying my constant is unused: Initialization of immutable value 'myConst' was never used; consider replacing with assignment to '_' or removing it if someVal["value"] != nil { let myConst = someVal["value"] } So what will renaming let myConst = someVal["value"] into _ myConst = someVal["value"] do/mean? 回答1: You're not replacing let with _ , but you're replacing the variable name with it. If the variable isn't used anywhere in the code it's irrelevant so the line can be

问题 I am interested in having an XML layouts in Android change size depending on landscape or portrait viewing (and maybe other configurations later). <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_alignParentBottom="true" android:background="@drawable/stream_bg_1px_wide" android:layout_height="150dip" > In this example I just want to vary the 150dip size depending on landscape or portrait, not change anything else. I am

问题 First time user on stack overflow and I'm excited to be here. INTRO: I recently began the magical adventure into the world of Python programming - I love it. Now everything has gone smoothly in my awkward transition from C, but I'm having trouble creating something which would be synonymous to a HEADER file (.h). PROBLEM: I have medium sized dictionaries and lists (about 1,000 elements), lengthy enums, and '#defines' (well not really), but I can't find a CLEAN way to organize them all. In C,

问题 I posted this question before, but changed some variable names and realized my mistake too late, so this code is unaltered in any way. Error: Routing Error uninitialized constant Firefighters Rails.root: /Users/Vladdy/Dropbox/dev/firestaff Here's the relevant, erroring bit from routes.rb : # get '/firefighters/dashboard' => 'firefighters#dashboard' namespace :firefighters do get '/dashboard' => 'firefighters#dashboard' # Namely, this one. get '/dashboard/:date' => 'firefighters#dashboard' get

问题 class Actor { let agent: String? = "nobody" init(agent: String){ self.agent = agent // error: immutable value 'self.agent' may only be initialized once } } let John = Actor(agent: "xyz") I'm confused about the sequence that is happening here (I'm fully aware of the differences between var and let ). But why do I get that error? If I'm using the init method, then doesn't that mean I'm not using the default parameter? Why can't I change the default constant with another one? 回答1: You cannot

问题 class Actor { let agent: String? = "nobody" init(agent: String){ self.agent = agent // error: immutable value 'self.agent' may only be initialized once } } let John = Actor(agent: "xyz") I'm confused about the sequence that is happening here (I'm fully aware of the differences between var and let ). But why do I get that error? If I'm using the init method, then doesn't that mean I'm not using the default parameter? Why can't I change the default constant with another one? 回答1: You cannot

问题 Maybe I should just make this a public member, but I keep thinking it should be a constant. SCENARIO I have forms I'm rendering into PDFs (using iTextSharp). In code, the forms themselves all inherit a base class ( OrderForm ). Within OrderForm , there are a list of constants that I use for measurements when aligning things for the PDF rendering, such as LEFT_MARGIN , etc. These constants are used in several functions to determine where things go. All the forms are virtually identical as they

问题 Please consider the following code. struct foo { }; template<typename T> class test { public: test() {} const T& value() const { return f; } private: T f; }; int main() { const test<foo*> t; foo* f = t.value(); return 0; } t is a const variable and value() is a constant member-function which returns const T& . AFAIK, a const type is not assignable to a non-const type. But how foo* f = t.value(); compiles well. How this is happening and how can I ensure value() can be only assigned to const

问题 I'm declaring a number of static arrays in a Constants.m file, for example the numberOfRowsInSection count for my tableView: + (NSArray *)configSectionCount { static NSArray *_configSectionCount = nil; @synchronized(_configSectionCount) { if(_configSectionCount == nil) { _configSectionCount = [NSArray arrayWithObjects:[NSNumber numberWithInt:2], [NSNumber numberWithInt:2], [NSNumber numberWithInt:4], [NSNumber numberWithInt:3], [NSNumber numberWithInt:0], nil]; } return _configSectionCount; }

问题 I have a file like this: Executing resource: D:\waste2\SPC\depks_rtl_teller_custom.spc Executing resource: D:\waste2\SPC\ifpks_msg_incoming_cluster.spc Failed to execute: Executing resource: D:\waste2\SQL\casapks_batch.sql Failed to execute: Executing resource: D:\waste2\SQL\depks_decbatop_kernel.sql Executing resource: D:\waste2\SQL\depks_services.sql Failed to execute: I need a batch file or perl script or ANT script to pick all the lines just in front of the string "Failed to execute:" and