scope

问题 Consider the following code: test1 <- "a" test2 <- "a" tryCatch(stop(), error= function(err){ print(test1) print(test2) test1 <- "b" test2 <<- "b" }) Result: print(test1) [1] "a" print(test2) [1] "b" The value of variable test1 is visible within the tryCatch block, but changing it with "<-" operator does not affect its value outside the tryCatch block. If a new value is assigned with <<- it has the desired effect. Why? Is using the <<- operator within the tryCatch block a recommended way to

问题 This question already has answers here : Declaring multiple variables in JavaScript (17 answers) Closed 4 years ago . I have a line in my source code written by someone else: var campaignLimits = 10, campaignsArray = new Array(); I just wanted to know, whether campaignsArray here becomes global variable, or the var applies to campaignsArray as well? 回答1: Assuming you have not used any programming pattern, If its written inside a function then its not global. (function() { var campaignLimits =

问题 This question already has answers here : Declaring multiple variables in JavaScript (17 answers) Closed 4 years ago . I have a line in my source code written by someone else: var campaignLimits = 10, campaignsArray = new Array(); I just wanted to know, whether campaignsArray here becomes global variable, or the var applies to campaignsArray as well? 回答1: Assuming you have not used any programming pattern, If its written inside a function then its not global. (function() { var campaignLimits =

问题 This question already has answers here : How to mock external dependencies in tests? [duplicate] (1 answer) How to mock specific methods but not all of them in Rust? (2 answers) How can I test stdin and stdout? (1 answer) Is there a way of detecting whether code is being called from tests in Rust? (1 answer) What is the proper way to use the `cfg!` macro to choose between multiple implementations? (1 answer) Closed 8 days ago . I'm trying to run unit tests on a function reducer . reducer

问题 Question If I do this: $checkName = function ($value) use ($min, $max) { function lengthTest($string, $min, $max) { $length = mb_strlen($string, 'UTF-8'); return ($length >= $min) && ($length <= $max); } }; 1) Is it legal PHP? And ... 2) Is the function lengthTest() in the global namespace, or limited to just the $checkName Closure object? Would it be a private member, then? 3) Can lengthTest() be refereced as a callback method for filter_var_array() like this? $filterInstructionsArray [

问题 What is variable declared within file scope in javascript? Is there anything file scope, considering multiple files are used in an app. 回答1: ES6 modules form their own file scope (as if the entire contents of the file were wrapped in a function). Variables declared in a module are completely inaccessible from outside that module (unless they're export ed). 回答2: In JavaScript, there are only 3 types of scope: Global Scope (i.e. every variable/function defined outside functions in a file or

问题 What is variable declared within file scope in javascript? Is there anything file scope, considering multiple files are used in an app. 回答1: ES6 modules form their own file scope (as if the entire contents of the file were wrapped in a function). Variables declared in a module are completely inaccessible from outside that module (unless they're export ed). 回答2: In JavaScript, there are only 3 types of scope: Global Scope (i.e. every variable/function defined outside functions in a file or

问题 What is variable declared within file scope in javascript? Is there anything file scope, considering multiple files are used in an app. 回答1: ES6 modules form their own file scope (as if the entire contents of the file were wrapped in a function). Variables declared in a module are completely inaccessible from outside that module (unless they're export ed). 回答2: In JavaScript, there are only 3 types of scope: Global Scope (i.e. every variable/function defined outside functions in a file or

问题 According to my programming language class, in a language that uses lexical scoping The body of a function is evaluated in the environment where the function is defined, not the environment where the function is called. For example, SML follows this behavior: val x = 1 fun myfun () = x val x = 10 val res = myfun() (* res is 1 since x = 1 when myfun is defined *) On the other hand, Python does not follow this behavior: x = 1 def myfun(): return x x = 10 myfun() # 10 since x = 10 when myfun is

问题 According to my programming language class, in a language that uses lexical scoping The body of a function is evaluated in the environment where the function is defined, not the environment where the function is called. For example, SML follows this behavior: val x = 1 fun myfun () = x val x = 10 val res = myfun() (* res is 1 since x = 1 when myfun is defined *) On the other hand, Python does not follow this behavior: x = 1 def myfun(): return x x = 10 myfun() # 10 since x = 10 when myfun is