Sort methods

[rs74]

a = add(multi(3)); a = a + mod(div(a + 3)) + sub(12)

How (and why) should this functions (add, multi, mod, div, sub) be sorted? I am thinking like this ->

1. multi (a = a) (first function)
2. mod (a + mod) (second function)
3. sub (a + mod + sub)
4. ?
5. ?

[buran]

Not clear what you ask.
What do you mean by "sorting"?
Are these functions from operator module?

[rs74]

Which function is the first to run? These functions should just be sorted (by me in general, not the program) in a list in the way they are executed(?).


Example:

multi
mod
sub
div
add

[buran]

Read evaluation order and operator precedence

Python evaluates expressions from left to right. Notice that while evaluating an assignment, the right-hand side is evaluated before the left-hand side.

So in your example:

1. it will first evaluate 3, resulting in 3
   
2. then it will evaluate multi(3) - this will throw error if multi expects 2 arguments, see below
   
3. then it will evaluate add(result from multi(3))
   
4. then it will assign the result from item 3 to a
   
5. then, on next line, it evaluate a - first term on the right-hand side.
   
6. then it will evaluate a+3
   
7. then it will evaluate div(result from a + 3)
   
8. then it will evaluate mod(result from div(result from a + 3))
   
9. then it evaluate 12
   
10. then it will evaluate sub(12)
    
11. then it will evaluate a + result from mod(result from div(result from a + 3)) = result from sub(12)
    
12. then will assign the result to a
    

You did not confirm but, I would assume these are functions from operator module, although there is no multi, but mul.
So, first of all, your example is invalid, because all these functions expect 2 arguments. e.g. mul(3) will throw error

>>> from operator import mul >>> mul(3) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: mul expected 2 arguments, got 1

[rs74]

Read evaluation order and operator precedence

Python evaluates expressions from left to right. Notice that while evaluating an assignment, the right-hand side is evaluated before the left-hand side.

So in your example:

1. it will first evaluate (3), resulting in 3
   
2. then it will evaluate multi(3) - this will throw error if multi expects 2 arguments, see below
   
3. then it will evaluate add(result from multi(3))
   
4. then it will assign the result from item 3 to a
   
5. then, on next line, it evaluate a - first term on the right-hand side.
   
6. then it will evaluate a+3
   
7. then it will evaluate div(result from a + 3)
   
8. then it will evaluate mod(result from div(result from a + 3))
   
9. then it evaluate 12
   
10. then it will evaluate sub(12)
    
11. then it will evaluate a + result from mod(result from div(result from a + 3)) = result from sub(12)
    
12. then will assign the result to a
    

You did not confirm but, I would assume these are functions from operator module, although there is no multi, but mul.
So, first of all, your example is invalid, because all these functions expect 2 arguments. e.g. mul(3) will throw error

>>> from operator import mul >>> mul(3) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: mul expected 2 arguments, got 1

Thanks. Yes, will read about evaluation order and operator precedence.

[DeaD_EyE]

Code execution is from left to right from top to down.
If the left or right operand is a function-call, then this is evaluated first.

The operator precedence is what you want to know: https://docs.python.org/3/reference/expr...precedence