parentheses

Is it possible to prevent death by parentheses?

由 好久不见. 提交于 2019-12-10 14:15:10
问题 Occasionally, I will write some code with way more parentheses than I like. if(!(new Day((((new Date()) / millisecondsPerDay) % 75)) instanceof oldDay))) { // Bonus points if that condition made any sense to you } It is hard to keep track of how many parentheses I need to put, especially when I'm not using an IDE that immediately tells me when something is wrong. In fact, I bet the above example doesn't match the parentheses correctly. I've been pegged with errors from death by parentheses

Why does this triple quoting solution fix path error?

由 左心房为你撑大大i 提交于 2019-12-10 11:33:41
问题 So I was running into a bit of a problem today with this bit of code: os.system("C:\Program Files (x86)\DOSBox-0.72\dosbox.exe") Upon execution I'd get this error message: 'C:\Program' is not recognized as an internal or external command, operable program or batch file. I assumed it was something to do with either the white space or the brackets, so I did a bit of digging online and after countless of ineffective "solutions" involving escape characters, I ended up finding a rather strange

laravel - why function call with no parentheses?

由 十年热恋 提交于 2019-12-10 02:06:36
问题 I see this in a laravel tutorial : Auth::user()->item; where item is a function, inside models\User.php : function item() { return $this->hasMany('Item', 'owner_id'); } where Item is for models\Item.php So why the parentheses is not needed when item function is called ? Like : Auth::user()->item(); If I put the parentheses, the browsers goes crazy and crash. Also, if I rename Item.php to Item2.php, rename class Item to Item2, and I do hasMany('Item2', 'owner_id') , it won't work. But why ?

Why doesn't the C++ compiler complain when I use functions without parentheses?

由 白昼怎懂夜的黑 提交于 2019-12-09 03:11:11
问题 I was looking at some code a friend sent me, and he said: "It compiles, but doesn't work". I saw that he used the functions without the parentheses, something like this: void foo(){ cout<< "Hello world\n"; } int main(){ foo; //function without parentheses return 0; } The first I said was "use parentheses, you have to". And then I tested that code - it does compile, but when executed doesn't work (no "Hello world" shown). So, why does it compile (no warning at all from the compiler GCC 4.7 ),

short circuiting and parenthesis

由 自闭症网瘾萝莉.ら 提交于 2019-12-08 17:02:15
问题 Does it matter how I group subexpressions when dealing with a single short-circuiting operator? a && b && c && d a && (b && (c && d)) (a && b) && (c && d) ((a && b) && c) && d Are the above expressions equivalent? 回答1: It is relatively easy to prove the equivalence for two simplified cases of three subexpressions: a && (b && c) --> a && bc // bc is a shorthand for b && c Here, a will be evaluated first. If it is false, short circuiting will prevent the evaluation of bc . If it is true, bc

Angular 5 child routes adding parentheses to the route

由 笑着哭i 提交于 2019-12-08 13:12:29
I have an Angular 5 application with a series of components. Some of the components are children of others, and some are not. I would like the application to have a structure such as: */my-account/overview // homepage */my-account/my-stuff */profile */non-default I have a DefaultComponent that contains some generic elements such as site navigation that I would like to be present on most of the pages (everything except for the */non-default route/component). My routing module defines the routes below: export const routes: Routes = [ { path: '', redirectTo: 'my-account', pathMatch: 'full' }, //

Longest `subsequence` of balanced parentheses

由 本秂侑毒 提交于 2019-12-08 04:00:19
问题 I am trying to solve a variant of a problem I asked earlier: Given a string of parentheses (length <= 1,000,000) and a list of range queries, find the longest subsequence of balanced parentheses within each of the ranges for each of the <= 100,000 queries I found this other SO question that is similar but only has an O(N^3) algorithm. I believe that a DP solution of the form dp[i, j] = longest balanced subsequence in [i .. j] should work because once computed, this would enable to to answer

EXC_BAD_ACCESS in statement block in Switch impact on imageViewPoistion

由 孤街浪徒 提交于 2019-12-07 14:26:03
问题 I have a strange situation. I get an exception on the following code on the close curly brackets of the switch statement imageViewPosition = self.imageView6.center; switch(direction) { case(1): if (starty-imageViewPosition.y>50) { imageViewPosition.y = starty+100; } else { imageViewPosition.y = starty; } break; case(2): ... } <----- Here i get the exception starty is a double class member. And imageViewPosition is a CGPoint. When I run it like this, I get a EXC_BAS_ACCESS exception. In the

sqlalchemy how to using AND in OR operation?

由 China☆狼群 提交于 2019-12-07 05:52:18
问题 i need to do this query: SELECT * FROM tbl_member WHERE (member_type==1 AND member_status==1) OR (member_type==2 and member_status==2) i've tried: q=session.query(tbl_member) \ .filter(or_(and_(tbl_member.member_type==1,tbl_member.member_status==1), \ and_(tbl_member.member_type==2,tbl_member.member_status==2))) and q=session.query(tbl_member) \ .filter(or_((and_(tbl_member.member_type==1,tbl_member.member_status==1)), \ (and_(tbl_member.member_type==2,tbl_member.member_status==2)))) the

How to set curly braces'/parentheses'/square brackets'/arithmetic operators' syntax highlight color in VIM?

由 荒凉一梦 提交于 2019-12-07 05:17:32
问题 How do I highlight operators/parentheses/brackets/etc. in VIM? I'm not interested in coloring matching or unmatching parentheses/brackets. I've tried ":hi cBracket/whatnot guifg=something" and ":hi Operator/cOperator guifg=something" but these don't seem to affect anything. 回答1: There are two parts to Vim syntax coloring: the syn command and the hi command. As far as I understand, you use syn to define syntax. For example: syn match parens /[(){}]/ Then you use hi to tell Vim how to highlight
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