symbols

问题 If you create 10,000 strings in a loop, a lot of garbage collection has to take place which uses up a lot of resources. If you do the same thing with symbols, you create objects which cannot be garbage collected. Which is worse? 回答1: If you refer to the same symbol in your loop, then it doesn't have to recreate that object everytime i.e. while i < 10000 i += 1 :im_using_this_symbol_here end Now if you use a string there instead, the string will be recreated 10K times. In general, use symbols

问题 What are the settings in Xcode to strip symbols for an iphone application? I use these settings in Xcode but still see classnames and their methods in the executable using a binary file editor. Deployment: 1) Deployment Post processing(checked) 2) Strip Debug Symbols During Copy(checked) 3) Strip Linked Product(checked) 4) Use Separate Strip(checked) Linking: 5) Dead Code Stripping(checked) GCC 4.0 - Code Generation 6) Generate Debug Symbols(NOT checked) 回答1: Objective-C class and method

问题 The following query results in an error due to the @ (at symbol). The query will work fine when it is removed. I tried escaping the @ character, but no luck. SELECT * FROM clients WHERE MATCH (form) AGAINST ('test@test.com' IN BOOLEAN MODE); The error produced is: #1064 - syntax error, unexpected '@', expecting $end Note that I am testing these queries in the phpMyAdmin SQL console area, so it's not a matter of an escape error with my other programming. MySQL server is version 5.6.17. Any

问题 I've just noticed that XCode shows "A+" symbol related with source control. What does it mean? 回答1: A+ stands for moving a file (renaming is treated as moving). All credit goes to user2129800, whose answer is in the comment under the question. 来源： https://stackoverflow.com/questions/18892827/xcode-a-source-control-symbol

问题 In a screen cast on Common List the author uses uninterned symbols for package names and exports. (defpackage #:foo (:use :cl) (:export #:bar #:baz)) (in-package #:foo) He also uses the sharp sign in front of anonymous functions. (defun transposed (m) (make-instance 'matrix :rows (matrix-cols m) :cols (matrix-rows m) :generator #'(lambda (i j) (matrix-at m j i)))) In the book Practical Common Lisp the sharp sign isn't used for package names and exports as far as I have read. What's the reason

问题 I have a .crash log from an ad-hoc version of my app that symbolicatecrash refuses to symbolicate. I have already applied the .patch to remove the 'die' command in symbolicatecrash after apple broke the script in XCode 3.2.6. Symbolicatecrash has worked for other crash logs but refuses to symbolicate this one. My ad hoc app was built and is stored in "Archived Applications", so there is no reason why XCode shouldn't be able to find it. I have even copied the .app and .dSYM files right next to

问题 Without modifying these two source files, is there a way to take the object files produced by compiling them, and convincing a linker to link foo in main_v1.c to bar in bar.c? main_v1.c void foo(void); int main(void) { foo(); } bar.c #include <stdio.h> void bar(void) { puts("bar()!"); } Modifying the object files themselves is fair game but assume that we might not even have the source code available. The platform is Linux. By insisting on a modest change to main_v1.c, and linking in an

问题 I want to use special symbols, but instead all I get printed question mark symbol � I tried {% autoescape 'html' %} {{ '©'|escape('html') }} {# won't be double-escaped #} {{ '©'|escape(strategy) }} {# will be double-escaped #} {% endautoescape %} and it did not work. 回答1: Use raw filter : {{ '©'|raw }} http://twig.sensiolabs.org/doc/filters/raw.html If the output is supposed to be HTML, you can also use HTML entity notation, for example trademark sign: {{ '™' }} or email sign: {{ '@' }} 回答2:

问题 I'm working on a site that is very text heavy and the site looks fine in Chrome, Firefox and Safari. But when I test it in Internet Explorer it has random scattered superscript "L" Symbols on the text. I looked back to the code to see if there was anything extra written in it causing the L but there was nothing. The main problem is on the homepage. Here's the site: http://emilymagnuson.com/mynews2/index.html And you have to look at it in IE to see the problem. 回答1: Looking at the HTML of your

问题 If I do this: ('a 'b 'c) I get this: c Why? 回答1: The link Hauleth posted is a good overview to symbols but the answer to your question is that calling a symbol as a function is equivalent to looking that symbol up in the first argument. ('a 'b) is equivalent to (get 'b 'a) The documentation for get shows that you can pass an optional third argument as the default. In your example 'c is treated as the default and returned since 'b is not a map and 'a can't be found. 来源： https://stackoverflow