Python dynamic variable name definition and invocation

Dynamic Variable name Assignment

You need to dynamically generate variables when using Tkinter, such as dynamically generating VAR1...VAR10 variables

• Using exec to dynamically assign values

execIn Python3 is a built-in function that supports the dynamic execution of Python code.

Example:

In [1]: for i in range(5):   ...:     exec(‘var{} = {}‘.format(i, i))   ...:In [2]: print(var0, var1, var2, var3 ,var4)0 1 2 3 4

• Using namespaces to dynamically assign values

In the Python namespace, store the variable name and value in the dictionary.
You can locals() globals() get the local namespace and the global namespace, respectively, by using the function.

Example

In [2]: names = locals()In [3]: for i in range(5):   ...:     names[‘n‘ + str(i) ] = i   ...:In [4]: print(n0, n1, n2, n3, n4)0 1 2 3 4

• The properties of a class object that uses dynamic variables in a class are stored in the property __dict__ . __dict__is a dictionary, the key is the property name, and the value corresponds to the value of the property.

In [1]: class Test_class(object):   ...:     def __init__(self):   ...:         names = self.__dict__   ...:         for i in range(5):   ...:             names[‘n‘ + str(i)] = i   ...:In [2]: t = Test_class()In [3]: print(t.n0, t.n1, t.n2, t.n3, t.n4)0 1 2 3 4

Calling dynamic variables

In fact, for repetitive variables, we don't normally call variables like this: var0, var1, var2, var3 ,var4....varN you can use the following method to invoke variables dynamically

First define the following variables:

In [1]: for i in range(5):   ...:     exec(‘var{} = {}‘.format(i, i))   ...:In [2]: print(var0, var1, var2, var3 ,var4)0 1 2 3 4

Using the EXEC function

Similarly, you can use the exec call variable

In [3]: for i in range(5):   ...:     exec(‘print(var{}, end=" ")‘.format(i))   ...:0 1 2 3 4

Using namespaces

Because the command space locals() and globals() all return a dictionary, use the dictionary get method to get the value of the variable

In [4]: names = locals()In [5]: for i in range(5):   ...:    print(names.get(‘var‘ + str(i)), end=‘ ‘)   ...:0 1 2 3 4

Python dynamic variable name definition and invocation