If you want to simply access a global variable you just use its name. However to change its value you need to use the global keyword. E.g. global someVar someVar = 55 This would change the value of the global variable to 55. Otherwise it would just assign 55 to a local variable. The order … Read more
When people talk about global variables in other languages it means something different to what it does in PHP. That’s because variables aren’t really global in PHP. The scope of a typical PHP program is one HTTP request. Session variables actually have a wider scope than PHP “global” variables because they typically encompass many HTTP … Read more
The keyword global is only useful to change or create global variables in a local context, although creating global variables is seldom considered a good solution. def bob(): me = “locally defined” # Defined only in local context print(me) bob() print(me) # Asking for a global variable The above will give you: locally defined Traceback … Read more
I wrote this answer back in ’09 when Android was relatively new, and there were many not well established areas in Android development. I have added a long addendum at the bottom of this post, addressing some criticism, and detailing a philosophical disagreement I have with the use of Singletons rather than subclassing Application. Read … Read more
The problem with global variables is that since every function has access to these, it becomes increasingly hard to figure out which functions actually read and write these variables. To understand how the application works, you pretty much have to take into account every function which modifies the global state. That can be done, but … Read more
Python doesn’t have variable declarations, so it has to figure out the scope of variables itself. It does so by a simple rule: If there is an assignment to a variable inside a function, that variable is considered local.[1] Thus, the line counter += 1 implicitly makes counter local to increment(). Trying to execute this … Read more
This has nothing to do with Python; global variables are bad in any programming language. However, global constants are not conceptually the same as global variables; global constants are perfectly harmless. In Python the distinction between the two is purely by convention: CONSTANTS_ARE_CAPITALIZED and globals_are_not. The reason global variables are bad is that they enable … Read more
What is supposed to happen is that ‘named elements’ are added as apparent properties of the document object. This is a really bad idea, as it allows element names to clash with real properties of document. IE made the situation worse by also adding named elements as properties of the window object. This is doubly … Read more
Using extern is only of relevance when the program you’re building consists of multiple source files linked together, where some of the variables defined, for example, in source file file1.c need to be referenced in other source files, such as file2.c. It is important to understand the difference between defining a variable and declaring a … Read more
You can use a global variable within other functions by declaring it as global within each function that assigns a value to it: globvar = 0 def set_globvar_to_one(): global globvar # Needed to modify global copy of globvar globvar = 1 def print_globvar(): print(globvar) # No need for global declaration to read value of globvar … Read more