#🔒 Efficiency and Coding Principles?

33 messages · Page 1 of 1 (latest)

worldly perch
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I have some homework assigned to me in which I must parse a certain 'made up' language into Python. This code works perfectly for what the homework assignment is on and passes all tests but it would be highly beneficial if I am able to understand it more through the assistance of you guys. I have had a few mates assist me with this and therefore I would like help learning where I can make this code more efficient and if it's following basic coding principles. I am a first year computer science student.

twin shaleBOT
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@worldly perch

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worldly perch
boreal shard
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There are quite some functions that are not included in this module you pasted

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Are those defined somewhere, or did you get an explanation of what they do? @worldly perch

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Like expect_token

worldly perch
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They are defined in the code but that is provided to us

worldly perch
boreal shard
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What you just pasted is provided by your prof?

worldly perch
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Everything besides def parse_program(token_list):

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everything in that function is mine

boreal shard
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Alrighty

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Well first of all, and this is out of your control, the provided functions and this module does some stuff that is a bit smelly

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For example, there are global variables which are used throughout the functions. Global constants are OK, global variables are kinda bad

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And then also, the values you provide to these functions as arguments are modified in the function body

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Thus, they are not "pure functions"

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The global variable I'm talking about is the cur_tok_index

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One example of why this is bad, is let's say you want to run parse_program twice, the cur_tok_index will already be modified, so it will be out of index the second run.

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Does this all make sense what I'm saying?

worldly perch
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Yes, that makes perfect sense

boreal shard
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Using global vars and mutating provided arguments in function bodies makes it very hard to read code

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Because I cannot just look at 1 function, I will have to inspect all the rest of the code as well, as they are all interconnected now

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Instead of properly separating the responsibilities, such that each function is responsible for doing 1 thing

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The second more general feedback is that you wrote all the logic of the function directly into the main "parse_program" function

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You could have made a function f.e.

def validate_header(token_list):
    expect_token("ROBOT", token_list)
    expect_token("IDENTIFIER", token_list)
    expect_token("COLON", token_list)
    expect_token("BEGIN", token_list)
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And then replace those lines in parse_program with validate_header

worldly perch
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I have to head out now but this makes a lot of sense- seems better to use, I'll definetly try incorporate such

boreal shard
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The example is a bit nitpicky, but the idea is to use helper functions

unkempt oasis
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a lot could be done. separation of logic, simplifying procedures, and extracting repeated lines (like stdio.writef("ERROR ...") ) .

twin shaleBOT
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