has built-in functions and statements to facilitate this dynamic code
) is a built-in
function that evaluates a string, and
locals]] is a statement (not a function:
no parentheses needed) that executes a string. The following
clarifies how it works:
>>> exec "print 'this expression was compiled on the fly' " this expression was compiled on the fly >>> exec "x = 3.14" >>> eval("x + 1") 4.14
Let’s pause for a moment and consider the implications of this code. You could pass a chunk of text to a running Python application, and it’s parsed, compiled, and executed on the fly. In Python, the interpreter is always available. Few languages offer this capability, and it’s what makes Python a good macro language.