Menu
Python offers the function globals() to access a dictionary of all global variables. Why is that a function and not a variable? The following works:
g = globals()
g["foo"] = "bar"
print foo # Works and outputs "bar"
What is the rationale behind hiding globals in a function? And is it better to call it only once and store a reference somewhere or should I call it each time I need it?
IMHO, this is not a duplicate of Reason for globals() in Python?, because I'm not asking why globals() exist but rather why it must be a function (instead of a variable __globals__).
264
Python – globals() function globals() function in Python returns the dictionary of current global symbol table. Symbol table: Symbol table is a data structure which contains all necessary information about the program. These include variable names, methods, classes, etc.
In Python, global keyword allows you to modify the variable outside of the current scope. It is used to create a global variable and make changes to the variable in a local context.
In the programming world, a global variable in Python means having a scope throughout the program, i.e., a global variable value is accessible throughout the program unless shadowed. A global variable in Python is often declared as the top of the program.
Global variables are variables that are accessible regardless of scope. Traditionally, functions operate within a local scope with limited access to variables that are not passed as a parameter. Setting a variable as global breaks the rules of encapsulation so that the specified variable is more accessible.
Because it may depend on the Python implementation how much work it is to build that dictionary.
In CPython, globals are kept in just another mapping, and calling the globals() function returns a reference to that mapping. But other Python implementations are free to create a separate dictionary for the object, as needed, on demand.
This mirrors the locals() function, which in CPython has to create a dictionary on demand because locals are normally stored in an array (local names are translated to array access in CPython bytecode).
So you'd call globals() when you need access to the mapping of global names. Storing a reference to that mapping works in CPython, but don't count on other this in other implementations.
135
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
