The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm bit confused about how the global variables work.
I have a large project, with around 50 files, and I need to define global variables for all those files. But again, it didn't work.
How should I implement this? I understand that it cannot work like that, when the two files don't really know each other well subfile doesn't know mainbut I can't think of how to do it, without using io writing or pickle, which I don't want to do. The problem is you defined myList from main. Here is a clean way to solve this problem: move all globals to a file, I call this file settings. This file is responsible for defining globals and initializing them:.
Note that subfile does not call init — that task belongs to main. See Python's document on sharing global variables across modules :. The canonical way to share information across modules within a single program is to create a special module often called config or cfg. Import the config module in all modules of your application; the module then becomes available as a global name. You can think of Python global variables as "module" variables - and as such they are much more useful than the traditional "global variables" from C.
It defines everything so that it is globally available with the exception of local variables in the imports of course. In case you are using the global in other module and you want to set the global dynamically, pay attention to import the other modules after you set the global variables, for example:.
Your 2nd attempt will work perfectly, and is actually a really good way to handle variable names that you want to have available globally.
But you have a name error in the last line. Here is how it should be:. Learn more. Using global variables between files? Ask Question. Asked 7 years, 5 months ago. Active 28 days ago. Viewed k times.
What I did was define them in my projects main. Actually, your second approach works just fine for me. Can you be more specific on what you me by "it didn't work"? NameError: name 'myList' is not defined from main. Active Oldest Votes.Sponsored by and others. Copy code. Please tell us why you want to mark the subject as inappropriate.
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Traditional way is:. A family guy with fun loving nature. Love computers, programming and solving everyday problems. Find me on Facebook and Twitter. Please help me out for this. Not sure what you are asking here. Please make it more clear. Not sure if you are looking for any ajax based solution. I want to generate automated buyer code. In struts2 template I have country name. When i select country name from country drop down i get country code ex.
If in case i selct 3rd buyer from China then i want to display buyer code as CHN Please help me for this. My point is: if in your first example you were to alert the window. I do not write only for experts, rather my readers are beginners and medium level experts with some hand-on.
Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have two source files that need to access a common variable. What is the best way to do this? Should the declaration of the variable global be static, extern, or should it be in a header file included by both files, etc?
The global variable should be declared extern in a header file included by both source files, and then defined in only one of those source files:. While it is not necessary, I suggest the name source1. In the same way source2. Of course you really don't want to be doing this and should probably post a question about what you are trying to achieve so people here can give you other ways of achieving it.
Learn more. Asked 9 years, 7 months ago. Active 3 years, 5 months ago. Viewed 80k times. Possible duplicate of this question. Rework the code to use something other than global variables - or retag the question as "C". If the scope can be narrowed down so that only internal class members use the accessor, all the better.
Few variables are truly "global". With respect to global the "best way" is not to do that at all. Active Oldest Votes. The global variable should be declared extern in a header file included by both source files, and then defined in only one of those source files: common.
James e. James k 37 37 gold badges silver badges bronze badges. If you want more info and explanation behind this : stackoverflow. You add a "header file", that describes the interface to module source1. In one file you declare it as in source1. Patrick Patrick 7, 6 6 gold badges 46 46 silver badges 68 68 bronze badges. You should achieve that the compiler gets the same extern declaration for each compilation unit, that needs the declaration.
When you spread the externs over all files that needs extern access to the variable, function, That's why: don't declare extern in the consuming. Sign up or log in Sign up using Google.
In the first page an instructor must enter information about his class an its students number, and then when done, he clicks next and a new page opens asking for each student information and grades. But when changing from the first page to the second the variable of the students number becomes undefined.
I'm using this part. Here is an example of using window. This will not work accross different domains because of the Same-origin policy. The example consists of two pages hosted on jsfiddle. Either way there is no server side communication involved in this example.
The first page allows the user to enter some text in a textarea element. There is a save button which when clicked will fire a click event that executes the save handler the anonymous function specified as the second attribute of addEventListener that gets the user entered text and saves it in localStorage with the key mySharedData. The second page recalls the saved text from the key mySharedData that is in localStorage and displays it in the textarea. Both examples are wrapped in an anonymous closure which is executed immediately, and into which we pass the window object which we then reference as the variable named global.
Which is what you're trying to do although on a different page with:. To pass around values from one page to the other you can use:.
Learn more. Sharing a variable between multiple html pages Ask Question. Asked 6 years, 11 months ago. Active 3 years, 3 months ago. Viewed 46k times. Active Oldest Votes. Alternatives would be to use: cookiesonce again the Same-origin policy would apply.
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Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have heard that global variables are bad and you better use "var" before the references. But is this a case where global variables are good?
Global variables are almost never a good thing maybe an exception or two out there In this case, it looks like you really just want to export your "name" variable. I'm unable to find an scenario where a global var is the best option, of course you can have one, but take a look at these examples and you may find a better way to accomplish the same:.
You need some value that it's the same across the application, but it changes depending on the environment production, dev or testthe mailer type as example, you'd need:. To decide which config will be loaded make a main config file this will be used all over the application. Not a big fan of this one, but at least you can track the use of the 'name' citing the OP's example and put validations in place. There could be a use case when there is no other solution than having a global varbut usually you can share the data in your app using one of these scenarios, if you are starting to use node.
Save any variable that want to be shared as one object. Then pass it to loaded module so it could access the variable through object reference. To share variable between module you can use function to get the value of variable between the main and the modules.
This is the basis for creating global variables in Node by declaring variables without the var keyword. While variables declared with the var keyword remain local to a module. With a different opinion, I think the global variables might be the best choice if you are going to publish your code to npmcuz you cannot be sure that all packages are using the same release of your code.
So if you use a file for exporting a singleton object, it will cause issues here. You can choose globalrequire. Learn more. Share variables between files in Node.Global variables in JS
Ask Question. Asked 9 years, 6 months ago. Active 1 year, 1 month ago. Viewed k times. Amit G 1, 2 2 gold badges 18 18 silver badges 42 42 bronze badges.
OK, guys, here's my little test too. I had a similar problem, so I decided to test out 3 situations:. Instead of browsing tutorials, I found it easier to try it out, so I did. Or into your PHP page if you will. Please correct me if I'm wrong here. If you are concerned that "local storage" may not be supported in very old browsers, consider using an existing plug-in which checks the availability of "local storage" and uses other methods if it isn't available.