Well, you can use the typeof operator, and if the identifier doesn’t exist in any place of the scope chain, it will not throw a ReferenceError, it will just return “undefined”: if (typeof ModuleName != ‘undefined’) { //… } Remember also that the this value on Global code, refers to the global object, meaning that … Read more
Because that’s the way it is, according to the C Standard. The reason for that is efficiency: static variables are initialized at compile-time, since their address is known and fixed. Initializing them to 0 does not incur a runtime cost. automatic variables can have different addresses for different calls and would have to be initialized … Read more
Update of 2018-10-10: The most succinct way to carry out this specific task is to use list2env() like so: ## Create an example list of five data.frames df <- data.frame(x = rnorm(25), g = rep(factor(LETTERS[1:5]), 5)) LIST <- split(df, df$g) ## Assign them to the global environment list2env(LIST, envir = .GlobalEnv) ## Check that it … Read more
The $GLOBALS array can be used instead: $GLOBALS[‘a’] = ‘localhost’; function body(){ echo $GLOBALS[‘a’]; } From the Manual: An associative array containing references to all variables which are currently defined in the global scope of the script. The variable names are the keys of the array. If you have a set of functions that need … Read more
If you need a global cross-module variable maybe just simple global module-level variable will suffice. a.py: var = 1 b.py: import a print a.var import c print a.var c.py: import a a.var = 2 Test: $ python b.py # -> 1 2 Real-world example: Django’s global_settings.py (though in Django apps settings are used by importing … Read more
This is a pretty famous difference between Windows and Unix-like systems. No matter what: Each process has its own address space, meaning that there is never any memory being shared between processes (unless you use some inter-process communication library or extensions). The One Definition Rule (ODR) still applies, meaning that you can only have one … Read more
You need to declare the variable before you include the helpers.js file. Simply create a script tag above the include for helpers.js and define it there. <script type=”text/javascript” > var myFunctionTag = false; </script> <script type=”text/javascript” src=”https://stackoverflow.com/questions/2932782/js/helpers.js”></script> … <script type=”text/javascript” > // rest of your code, which may depend on helpers.js </script>
You need to set up your global core.excludesfile configuration file to point to this global ignore file e.g: *nix or Windows git bash: git config –global core.excludesFile ‘~/.gitignore’ Windows cmd: git config –global core.excludesFile “%USERPROFILE%\.gitignore” Windows PowerShell: git config –global core.excludesFile “$Env:USERPROFILE\.gitignore” For Windows it is set to the location C:\Users\%username%\.gitignore. You can verify that … Read more
They clutter up the global namespace and are slower to look up than local variables. First of all, having many global variables is always a bad thing because it’s easy to forget you declared a variable somewhere and accidentally re-declare it somewhere else. If your first variable was local then you don’t have a problem. … Read more
Compare this, without using nonlocal: x = 0 def outer(): x = 1 def inner(): x = 2 print(“inner:”, x) inner() print(“outer:”, x) outer() print(“global:”, x) # inner: 2 # outer: 1 # global: 0 To this, using nonlocal, where inner()‘s x is now also outer()‘s x: x = 0 def outer(): x = 1 … Read more