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Code cleanup can also refer to the removal of all computer programming from source code, or the act of removing temporary files after a program has finished executing.. For instance, in a web browser such as Chrome browser or Maxthon, code must be written in order to clean up files such as cookies and storage. [6]
PHP has a global keyword and a number of unusual ways of using global variables. Variables declared outside functions have file scope (which is for most purposes the widest scope). However, they are not accessible inside functions unless imported with the global keyword (i.e., the keyword accesses global variables, it does not declare them).
Non-local variables are the primary reason it is difficult to support nested, anonymous, higher-order and thereby first-class functions in a programming language. If the nested function or functions are (mutually) recursive, it becomes hard for the compiler to know exactly where on the call stack the non-local variable was allocated, as the frame pointer only points to the local variable of ...
Variable scope in Python is implicitly determined by the scope in which one assigns a value to the variable, unless scope is explicitly declared with global or nonlocal. [ 22 ] Note that the closure's binding of a name to some value is not mutable from within the function.
Both these rules can be overridden with a global or nonlocal (in Python 3) declaration prior to use, which allows accessing global variables even if there is a masking nonlocal variable, and assigning to global or nonlocal variables. As a simple example, a function resolves a variable to the global scope: >>>
The Python programming language includes extensive support for creating and manipulating symbol tables. [5] Properties that can be queried include whether a given symbol is a free variable or a bound variable, whether it is block scope or global scope, whether it is imported, and what namespace it belongs to.
An external variable can be accessed by all the functions in all the modules of a program. It is a global variable.For a function to be able to use the variable, a declaration or the definition of the external variable must lie before the function definition in the source code.
A built-in function, or builtin function, or intrinsic function, is a function for which the compiler generates code at compile time or provides in a way other than for other functions. [23] A built-in function does not need to be defined like other functions since it is built in to the programming language.