237
votes
Accepted
Should we eliminate local variables if we can?
Code is read much more often than it is written, so you should take pity on the poor soul who will have to read the code six months from now (it may be you) and strive for the clearest, easiest to ...
- 1,324
119
votes
Accepted
Clean Code: Functions with few parameters
I don't share your opinion. In my opinion using global variables is a worse practice than more parameters irrespective of the qualities you described. My reasoning is that more parameters may make a ...
- 9,167
109
votes
How do variables in C++ store their type?
Variables (or more generally: “objects” in the sense of C) do not store their type at runtime. As far as machine code is concerned, there is only untyped memory. Instead, the operations on this data ...
- 133k
103
votes
Accepted
Why do so few languages with a variable-type 'operator' exist?
Operators are just functions under funny names, with some special syntax around.
In many languages, as varied as C++ and Python, you can redefine operators by overriding special methods of your class....
- 24.2k
98
votes
Should we eliminate local variables if we can?
Some highly upvoted comments stated this, but none of the answers I saw did, so I will add it as an answer. Your main factor in deciding this issue is:
Debuggability
Often, developers spend far more ...
- 3,576
73
votes
Using compound statements ("{" ... "}" blocks) to enforce variable locality
It is indeed a good practice to keep your variable's scope small. However, introducing anonymous blocks into large methods only solves half the problem: the scope of the variables shrinks, but the ...
- 108k
71
votes
Accepted
Why are variables declared without a value in C?
Versions of C up to and including C89 (i.e. the language version standardised in 1989; note this was the last major revision to the C standard before 1999) allowed variables to be declared only at the ...
- 23.2k
69
votes
Clean Code: Functions with few parameters
You should avoid global variables like the plague.
I wouldn't put a hard limit to number of arguments (like 3 or 4), but you do want to keep them to a minimum, if possible.
Use structs (or objects ...
- 1,190
69
votes
Accepted
What's the difference between a variable and a memory location?
A variable is a logical construct that goes to the intent of an algorithm, whereas a memory location is a physical construct that describes the operation of a computer. Generally speaking, in order ...
- 33.6k
60
votes
Accepted
Do inline expressions obstruct readability of code?
Personally I prefer having temporary variables with explicit names (but don't abuse them either).
For me:
void foo()
{
int const number_of_elements = (function_1() + function_2()) / function_3(); /...
- 1,020
58
votes
Clean Code: Functions with few parameters
We're talking about cognitive load, not syntax. So the question is... What is a parameter in this context?
A parameter is a value which affects the behaviour of the function. The more parameters, the ...
- 1,475
54
votes
How do variables in C++ store their type?
The other answer explains well the technical aspect, but I'd like to add some general "how to think about machine code".
The machine code after the compilation is pretty dumb, and it really just ...
- 1,844
48
votes
Should we eliminate local variables if we can?
Only if it makes the code easier to understand. In your examples, I think it makes it harder to read.
Eliminating the variables in the compiled code is a trivial operation for any respectable ...
- 27.7k
42
votes
Accepted
Why should I use namedtuple over SimpleNamespace when not using dict, they seem very similar
SimpleNamespace is basically just a nice facade on top of a dictionary. It allows you to use properties instead of index keys. This is nice as it is super flexible and easy to manipulate.
The ...
- 7,813
40
votes
Why are variables declared without a value in C?
It's not just a question of sytle. The two ways of declaring the variable are not equivalent:
In the first case, i exists after the loop and you could use it. This is useful, for example if the ...
- 75.9k
38
votes
Clean Code: Functions with few parameters
Having many parameters is considered undesirable, but turning them into fields or global variables is a lot worse because it doesn't solve the actual problem but introduce new problems.
Having many ...
- 57.7k
36
votes
Accepted
Does it make sense to create blocks just to reduce a variable's scope?
First, speaking to the underlying mechanics:
In C++ scope == lifetime b/c destructors are invoked on the exit from the scope. Further, an important distinction in C/C++ we can declare local objects. ...
- 33.6k
35
votes
Clean Code: Functions with few parameters
IMHO your question is based on a misunderstanding. In "Clean Code", Bob Martin does not suggest to replace repeated function parameters by globals, that would be a really awful advice. He suggest to ...
- 203k
33
votes
Accepted
What does "set" mean in programming languages like C#?
This question is one of English semantics, not programming, which initially urged me to vote to close this question as being off topic.
However, because "set" is notoriously the word with ...
- 47.5k
29
votes
Should we eliminate local variables if we can?
Your question "is it a good practice to eliminate a local variable if it is just used one time in the scope?" is testing the wrong criteria. A local variable's utility does not depend on the number of ...
- 2,954
27
votes
Does it make sense to create blocks just to reduce a variable's scope?
In my opinion it would be more clear to pull the block out into its own method. If you left this block in, I would hope to see a comment clarifying why you're putting the block there in the first ...
- 444
26
votes
Do inline expressions obstruct readability of code?
I think there are two key factors here:
How complex is the expression?
How meaningful is the intermediate variable?
Take an example where we have three elements to get a final price:
total = price + ...
- 5,742
24
votes
Accepted
How to name a Boolean variable that represents either of two options?
Don't use a Boolean. Use an enum. E.g TransactionType with instances Buy and Sell.
That is unambiguous and far easier to understand.
If you want to persist the data efficiently, the boolean can be a ...
- 4,548
22
votes
Using compound statements ("{" ... "}" blocks) to enforce variable locality
Often if you find places to create such a scope it's an opportunity to extract out a function.
In a language with pass-by-reference you would instead call swap(x,y).
For writing the file that would ...
- 25.8k
21
votes
Accepted
How are variables stored in a language compiler or interpreter?
Interpreter
An intepreter will work about the way you guessed. In a simple model, it will maintain one dictionary with the variable names as dictionary keys and the variable values as dictionary ...
- 5,941
20
votes
Why does Kotlin require type after variable, rather than before?
From Kotlin's FAQ:
Why have type declarations on the right?
We believe it makes the code more readable. Besides, it enables some nice syntactic features, for instance, it is easy to leave type ...
- 5,139
20
votes
What's the difference between a variable and a memory location?
Is it safe to say that a variable is the same thing as a memory location?
No. Variable and memory location are two abstractions at two different abstraction levels. Variable and pointers are higher ...
- 12.3k
18
votes
Accepted
Why are variables in Python different from other programming languages'?
This is not a Python vs Other Languages distinction - it's actually Value Types vs Reference Types distinction. Python uses reference types, and while many modern languages also tend to use reference ...
- 12.1k
18
votes
Accepted
Is there a convention for returning multiple items?
I think the choices need to be considered strictly from the caller's point of view: what is the consumer most likely to need to do?
And what are the salient features of each collection?
The tuple ...
- 838
17
votes
Does it make sense to create blocks just to reduce a variable's scope?
They can be useful in Rust, with it's strict borrowing rules. And generally, in functional languages, where that block returns a value. But in languages like Java? While the idea seems elegant, in ...
- 12.1k
Only top scored, non community-wiki answers of a minimum length are eligible