[FIXED] C Preprocessor Macro equivalent for Python

Issue

I use to define macros (not just constants) in C like

#define loop(i,a,b) for(i=a; i<b; ++i)
#define long_f(a,b,c) (a*0.123 + a*b*5.6 - 0.235*c + 7.23*c - 5*a*a + 1.5)

Is there a way of doing this in python using a preprocess instead of a function?

*By preprocess I mean something that replaces the occurrences of the definition before running the code (actually not the whole code but the rest of the code, because since it's part of the code, I guess it will replace everything during runtime).

If there is, worth it? Will there be a significant difference in run time?

Solution

Well, if you're going to perform some really hard calculations that could be performed in advance, then, perhaps, this makes sense: usually users are more happy with fast programs rather than slow ones.

But, I'm afraid python isn't a good choice when it comes to 'raw performance', that is, speed of arithmetic calculations. At least if we talk about the standard python implementation, called CPython.

Alternatively, you could check other variants:

• PyPy. This is an alternative python implementation, in pure Python. Thanks to a JIT compiler it gives better performance but requires a lot more memory.
• Cython. This is an extension to Python, which allows one to [conveniently] create compileable snippets for perfomance critical parts of the code.
• Use a whatever external pre-processor you like. M4 and FilePP are what come to my mind first, but there're plenty of them.

Answered By - user3159253