Python compile()

The compile() method returns a Python code object from the source (normal string, a byte string, or an AST object).

The syntax of compile() is:

compile(source, filename, mode, flags=0, dont_inherit=False, optimize=-1)

compile() method is used if the Python code is in string form or is an AST object, and you want to change it to a code object.

The code object returned by compile() method can later be called using methods like: exec() and eval() which will execute dynamically generated Python code.

1. compile() Parameters

• source – a normal string, a byte string, or an AST object
• filename – file from which the code was read. If it wasn’t read from a file, you can give a name yourself
• mode – Either exec or eval or single.
  • eval – accepts only a single expression.
  • exec – It can take a code block that has Python statements, class and functions, and so on.
  • single – if it consists of a single interactive statement
• flags (optional) and dont_inherit (optional) – controls which future statements affect the compilation of the source. Default Value: 0
• optimize (optional) – optimization level of the compiler. Default value -1.

2. Return Value from compile()

compile() method returns a Python code object.

3. Example: How compile() works?

codeInString = 'a = 5\nb=6\nsum=a+b\nprint("sum =",sum)'
codeObejct = compile(codeInString, 'sumstring', 'exec')

exec(codeObejct)

Output

sum = 11

Here, source is in normal string form. The filename is sumstring. And, the exec mode later allows the use of exec() method.

compile() method converts the string to Python code object. The code object is then executed using exec() method.