Is it possible to somehow inline a function in python? ( for both performance + maintainability )

Question

Is it possible to somehow inline a function in python?

I have a very long function in python, which I want to split up for readability in several functions. So the parts gets called only from one point, the in program, but very often.

This reduces performance since function calls are very expensive.

Is there a method to both maintain the unsplitted performance, while improving readability/maintainence?

Answer 1

There are several ways to inline in Python

Besides numba and similar JIT compilers ( which retain their own inline caches ), that may help you in JIT-code-reuse, as you denoted in numerous re-call of the unspecified function, there are several ways how to inline into Python code.

---

Inline symbolic x86 ASM assembly language into python

from pyasm              import Program
from pyasm.data         import String
from pyasm.macro        import syscall
from pyasm.instructions import mov, ret, push, add
from pyasm.registers    import eax, ebx, ecx, edx, ebp
import sys

def example():
    msg = 'Hello World!'
    prog = Program(     # _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
                        #
                        ### ASSUME NOTHING - a lovely ASM note to always remember & self.remind
                        mov(ebx, 1),
                        mov(ecx, String(msg)),
                        mov(edx, len(msg)),
                        syscall('write'),
                        ret(),
                        # _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
                        )
    fun = prog.compile()
    fun()

if __name__ == '__main__':
    example()

Inline ^almost c language into python

from pycca.cc import CCode, Function, Assign, Return

code = CCode( [ Function( 'int', 'add_one', [( 'int', 'x' )],
                        [
                          Assign( x='x + 1' ),
                          Return('x')
                          ])
                ])
print code.dump_asm()
print "3 + 1 = %d" % code.add_one( 3 )

For details & other options look at >>> this

---

Inline c language into python ^{( since 2001 )}

import PyInline, __main__

m = PyInline.build( language     = "C",
                    targetmodule = __main__,
                    code         = """
                                   /*_______________________________WORLDS-OF-C*/


                                     double my_C_adder( double a, double b )
                                     {
                                                        return a + b;
                                     }


                                   /*_______________________________WORLDS-OF-C*/
                                  """
                    )

print my_C_adder( 4.5, 5.5 )                     # Should print out "10.0"

Another approach at >>> PyInline

Answer 2

CPython interpreter does not support function inlining.

For performance-critical sections you may consider writing C-extension or using C Foreign Function Interface library.

C Foreign Function Interface for Python. The goal is to provide a convenient and reliable way to call compiled C code from Python using interface declarations written in C.

Another alternative is PyPy interpreter, which is equipped with JIT compiler and tends to achieve huge performance gains.

It depends greatly on the type of task being performed. The geometric average of all benchmarks is 0.14 or 7.0 times faster than CPython

Answer 3

No, Python doesn't support inline functions.