shadowing

In C++, what is the scope resolution (“order of precedence”) for shadowed variable names?

由 半世苍凉 提交于 2019-11-29 01:25:36
In C++, what is the scope resolution ("order of precedence") for shadowed variable names? I can't seem to find a concise answer online. For example: #include <iostream> int shadowed = 1; struct Foo { Foo() : shadowed(2) {} void bar(int shadowed = 3) { std::cout << shadowed << std::endl; // What does this output? { int shadowed = 4; std::cout << shadowed << std::endl; // What does this output? } } int shadowed; }; int main() { Foo().bar(); } I can't think of any other scopes where a variable might conflict. Please let me know if I missed one. What is the order of priority for all four shadow

Assignment operator in f#

由 て烟熏妆下的殇ゞ 提交于 2019-11-28 12:38:18
i have seen in ruby as well powershell programming we can assign variables like a,b=b,a . it actually swaps the variable . Is this possible in f# if so please guide me with some reference Generally, F# doesn't allow variable re-assignment. Rather it favors immutable named values via let bindings. So, the following is not possible: let a = 3 a = 4 Unless you explicitly mark a as mutable : let mutable a = 3 a <- 4 However, F# does allow in most situations variable "shadowing". The only restriction to this is that it can not be done on top level modules. But, within a function, for example, the

The concept of shadowing

由 三世轮回 提交于 2019-11-28 05:56:34
问题 Given the following code: public class A { static final long tooth = 1L; static long tooth(long tooth){ System.out.println(++tooth); return ++tooth; } public static void main(String args[]){ System.out.println(tooth); final long tooth = 2L; new A().tooth(tooth); System.out.println(tooth); } } Can you please explain me the concept of shadowing ? And another thing, what tooth is actually used in the code from the main method ? And i know it's a very ugly code, but ugly is the standard choice

In C++, what is the scope resolution (“order of precedence”) for shadowed variable names?

由 不羁岁月 提交于 2019-11-27 16:09:23
问题 In C++, what is the scope resolution ("order of precedence") for shadowed variable names? I can't seem to find a concise answer online. For example: #include <iostream> int shadowed = 1; struct Foo { Foo() : shadowed(2) {} void bar(int shadowed = 3) { std::cout << shadowed << std::endl; // What does this output? { int shadowed = 4; std::cout << shadowed << std::endl; // What does this output? } } int shadowed; }; int main() { Foo().bar(); } I can't think of any other scopes where a variable

Lambda capture and parameter with same name - who shadows the other? (clang vs gcc)

由 不想你离开。 提交于 2019-11-27 11:59:26
auto foo = "You're using g++!"; auto compiler_detector = [foo](auto foo) { std::puts(foo); }; compiler_detector("You're using clang++!"); clang++ 3.6.0 and newer print out "You're using clang++!" and warn about the capture foo being unused. g++ 4.9.0 and newer print out "You're using g++!" and warn about the parameter foo being unused. What compiler is more accurately following the C++ Standard here? wandbox example Update: as promised by the Core chair in the bottom quote, the code is now ill-formed : If an identifier in a simple-capture appears as the declarator-id of a parameter of the

question about variable scope and shadowing in java

由 与世无争的帅哥 提交于 2019-11-27 05:29:56
I got this situation i cant understand about shadowing. For example the following code class Foo { int a = 5; void goFoo(int a) { // No problem naming parameter as same as instance variable for (int a = 0; a < 5; a++) { } //Now the compiler complains about the variable a on the for loop // i thought that the loop block had its own scope so i could shadow // the parameter, why the compiler didnt throw an error when i named // the parameter same as the instance variable? } } Thank you por you patience. You can make a local variable shadow an instance/static variable - but you can't make one

Why does shadowed variable evaluate to undefined when defined in outside scope?

由 筅森魡賤 提交于 2019-11-27 05:28:06
Consider the following piece of code: <html><head></head> <body> <script type="text/javascript"> var outside_scope = "outside scope"; function f1() { alert(outside_scope) ; } f1(); </script> </body> </html> The output for this code is that the alert box displays the message "outside scope". But, if I slightly modify the code as: <html><head></head> <body> <script type="text/javascript"> var outside_scope = "outside scope"; function f1() { alert(outside_scope) ; var outside_scope = "inside scope"; } f1(); </script> </body> </html> the alert box displays the message " undefined ". I could have

Where can we use Variable Scoping and Shadowing in Go?

由 断了今生、忘了曾经 提交于 2019-11-26 21:45:05
问题 Some related posts I've found: go variable scope and shadowing Golang: variable scope inside if statements Limit the scope of variables storing error Also there are many use cases to Variable Scoping and Shadowing. Any code samples or answers will be appreciated. 回答1: Variable scoping and shadowing: Go is lexically scoped using blocks: The scope of a predeclared identifier is the universe block. The scope of an identifier denoting a constant, type, variable, or function (but not method)

Why are my dplyr group_by & summarize not working properly? (name-collision with plyr)

由 霸气de小男生 提交于 2019-11-26 15:11:59
I have a data frame that looks like this: #df ID DRUG FED AUC0t Tmax Cmax 1 1 0 100 5 20 2 1 1 200 6 25 3 0 1 NA 2 30 4 0 0 150 6 65 Ans so on. I want to summarize some statistics on AUC, Tmax and Cmax by drug DRUG and FED STATUS FED . I use dplyr. For example: for the AUC: CI90lo <- function(x) quantile(x, probs=0.05, na.rm=TRUE) CI90hi <- function(x) quantile(x, probs=0.95, na.rm=TRUE) summary <- df %>% group_by(DRUG,FED) %>% summarize(mean=mean(AUC0t, na.rm=TRUE), low = CI90lo(AUC0t), high= CI90hi(AUC0t), min=min(AUC0t, na.rm=TRUE), max=max(AUC0t,na.rm=TRUE), sd= sd(AUC0t, na.rm=TRUE))

question about variable scope and shadowing in java

由 孤者浪人 提交于 2019-11-26 11:36:11
问题 I got this situation i cant understand about shadowing. For example the following code class Foo { int a = 5; void goFoo(int a) { // No problem naming parameter as same as instance variable for (int a = 0; a < 5; a++) { } //Now the compiler complains about the variable a on the for loop // i thought that the loop block had its own scope so i could shadow // the parameter, why the compiler didnt throw an error when i named // the parameter same as the instance variable? } } Thank you por you
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