Function is a block of code which performs a specific task.

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112
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13answers
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Is it OK to split long functions and methods into smaller ones even though they won't be called by anything else? [duplicate]

Lately I've been trying to split long methods into several short ones. For example: I have a process_url() function which splits URLs into components and then assigns them to some objects via their ...
86
votes
10answers
6k views

One-line functions that are called only once

Consider a parameterless (edit: not necessarily) function that performs a single line of code, and is called only once in the program (though it is not impossible that it'll be needed again in the ...
44
votes
4answers
3k views

How do functional languages handle random numbers?

What I mean about that is that in nearly every tutorial I've read about functional languages, is that one of the great things about functions, is that if you call a function with the same parameters ...
39
votes
9answers
5k views

Beginning a sentence with a function name? [closed]

Occasionally while typing something up that relates to a case-sensitive programming language I end up starting a sentence with a function name. Now the rules of English state that the first word in a ...
37
votes
9answers
3k views

Why is Today() an example of an impure function?

It seems like, when reading something like this Wikipedia article about "pure functions", they list Today() as an example of an impure function but it seems pretty pure to me. Is it because there is ...
35
votes
12answers
4k views

Why do most programming languages have special keyword or syntax for declaring functions? [closed]

Most programming languages (both dynamically and statically typed languages) have special keyword and/or syntax that looks much different than declaring variables for declaring functions. I see ...
34
votes
9answers
9k views

Are there guidelines on how many parameters a function should accept?

I've noticed a few functions I work with have 6 or more parameters, whereas in most libraries I use it is rare to find a function that takes more than 3. Often a lot of these extra parameters are ...
33
votes
6answers
2k views

Why is “tight coupling between functions and data” bad?

I found this quote in "The Joy of Clojure" on p. 32, but someone said the same thing to me over dinner last week and I've heard it other places as well: [A] downside to object-oriented programming ...
28
votes
8answers
5k views

Is splitting up a function into several inner functions an anti-pattern? [duplicate]

Imagine a long and complicated process, which is started by calling function foo(). There are several consecutive steps in this process, each of them depending on result of the previous step. The ...
27
votes
4answers
1k views

How do programming languages define functions?

How do programming languages define and save functions/methods? I am creating an interpreted programming language in Ruby, and I am trying to figure out how to implement function declaration. My ...
26
votes
4answers
15k views

Why store a function inside a python dictionary?

I'm a python beginner, and I just learned a technique involving dictionaries and functions. The syntax is easy and it seems like a trivial thing, but my python senses are tingling. Something tells me ...
20
votes
8answers
4k views

What is the benefit of a function without parameters which only calls another function

A tutorial (for Javascript) I'm doing suggests we write a function like this one: function sayHello() { //Some comments explaining the next line window.alert("Hello"); } Other than ...
19
votes
2answers
1k views

Is it a good idea to provide different function signatures that do the same thing?

Here is a C++ class that gets constructed with three values. class Foo{ //Constructor Foo(std::string, int, char); private: std::string foo; char bar; int baz; }; All of ...
19
votes
3answers
8k views

Where should I put functions that are not related to a class?

I am working on a C++ project where I have a bunch of math functions that I initially wrote to use as part of a class. As I've been writing more code, though, I've realized I need these math functions ...
19
votes
4answers
12k views

Function declaration as var instead of function

More and more I'm seeing functions being declared like var foo = function() { // things }; Instead of how I had learned, like function foo() { // things } What's the difference? Better ...
17
votes
11answers
1k views

Why are we supposed to use short functions to sectionalize our code? [duplicate]

I've seen an increasing trend in the programming world saying that it is good practice to separate code blocks into their own functions. Obviously, if that code block is reusable, you should do that. ...
17
votes
2answers
1k views

Boolean Method Naming Affirmative vs Negative

Should boolean methods always take the affirmative form, even when they will only ever be used in the negative form? Say I wanted to check whether an entity exists before creating one, my argument is ...
14
votes
7answers
2k views

Function only returns unchanged parameter, useless?

I just found this function in the project I'm working at: -- Just returns the text unchanged. -- Note: <text> may be nil, function must return nil in that case! function Widget:wtr(text) ...
13
votes
1answer
1k views

Why does the C library use macros and functions with same name?

I am reading 'The Standard C Library' by PJ Plauger which is really interesting. The book explains not only how to USE the library but also how it is implemented. I have finished reading the ctype.h ...
12
votes
5answers
2k views

Why is *declaration* of data and functions necessary in C language, when the definition is written at the end of the source code?

Consider the following "C" code: #include<stdio.h> main() { printf("func:%d",Func_i()); } Func_i() { int i=3; return i; } Func_i() is defined at the end of the source code and ...
12
votes
7answers
3k views

Is there an optimal number of lines of code per function? [closed]

Functions are not only used to minimize duplication of code - they are also used to split up a long function into smaller ones to increase readability, as well as making the code self-commenting. Yet ...
12
votes
5answers
2k views

Why are PHP function signatures so inconsistent? [closed]

I was going through some PHP functions and I could not help notice the following: <?php function foo(&$var) { } foo($a); // $a is "created" and assigned to null $b = array(); foo($b['b']); ...
11
votes
4answers
7k views

C++ why & how are virtual functions slower?

Can anyone explain in detail, how exactly the virtual table works & what pointers are associated when virtual functions are called. If they are actually slower, can you show the time that the ...
11
votes
5answers
326 views

Convert list of 24-hour-precipitation values into total-by-hour

Let's say I have a list of precipitation values by hour, each showing how much rain happened in the prior 24 hours, ordered by date. For example: { '2012-05-24 12:00': 0.5, // .5" of rain from ...
10
votes
8answers
6k views

Feature vs. Function

Often I hear PMs (Project Managers) talk about feature and function. And I'm just so puzzled to differentiate them. Sometimes I think of a feature to be equivalent to a user story. Something like "As ...
10
votes
5answers
3k views

Multiple arguments in function call vs single array

I have a function that takes in a set of parameters, then applies to them as conditions to an SQL query. However, while I favored a single argument array containing the conditions themselves: ...
10
votes
2answers
715 views

Design: Object method vs separate class's method which takes Object as parameter?

For example, is it better to do: Pdf pdf = new Pdf(); pdf.Print(); or: Pdf pdf = new Pdf(); PdfPrinter printer = new PdfPrinter(); printer.Print(pdf); Another example: Country m = new ...
9
votes
1answer
2k views

Is there a difference between arguments and parameters?

It might be like this: Parameter means from the callers POV and arguments mean inside the procedure, or other way round. Or is there no difference? Update In Swedish we say "anropsparametrar" i.e. ...
9
votes
4answers
474 views

Are first-class functions a substitute for the Strategy pattern?

The Strategy design pattern is often regarded as a substitute for first-class functions in languages that lack them. So for example say you wanted to pass functionality into an object. In Java you'd ...
8
votes
8answers
4k views

Why Java does not allow function definitions to be present outside of the class?

Unlike C++, in Java, we cannot have just function declarations in the class and definitions outside of the class. Why is it so? Is it to emphasize that a single file in Java should contain only one ...
8
votes
3answers
1k views

Why can't we write nested shorthand functions in Clojure?

I tried to evaluate a Clojure expression with nested shorthand functions today, and it wouldn't let me. The expression was: (#(+ % (#(+ % (* % %)) %)) 5) ; sorry for the eye bleed The output was: ...
8
votes
2answers
947 views

What is an example of a continuation not implemented as a procedure?

An interesting discussion about the distinction between callbacks and continuations over on SO has prompted this question. By definition, a continuation is an abstract representation of the logic ...
7
votes
4answers
1k views

When would dynamic scoping be useful?

With dynamic scoping, a callee can access the variables of its caller. Pseudo C code: void foo() { print(x); } void bar() { int x = 42; foo(); } Since I have never programmed in a ...
6
votes
4answers
1k views

What is the name for a NON-self-calling function?

I have a collection of normal functions and self-calling functions within a javascript file. In my comments i want to say something along the lines of "This script can contain both self-calling and ...
6
votes
18answers
3k views

What do you name functions/variables/etc when you can't think of a good name?

When you are defining a function/variable/etc and are not sure what to name it, what do you name it? How do you come up with a name? If you use a temporary name as a place-card until you give it it's ...
6
votes
6answers
634 views

Why do many languages not support named parameters? [closed]

I was just thinking how much easier it would be to read code if, when calling a function, you could write: doFunction(param1=something, param2=somethingElse); I can't think of any drawbacks and it ...
6
votes
2answers
548 views

Is it bad practice to output from within a function?

For example, should I be doing something like: <?php function output_message($message,$type='success') { ?> <p class="<?php echo $type; ?>"><?php echo $message; ...
6
votes
3answers
2k views

Good use of wrapper functions?

What do you consider good use of wrapper functions? When are they useful abstractions and in what cases harmful and unnecessary complexity?
6
votes
3answers
515 views

Functional Methods on Collections

I'm learning Scala and am a little bewildered by all the methods (higher-order functions) available on the collections. Which ones produce more results than the original collection, which ones ...
6
votes
2answers
3k views

Reason for return statement in recursive function call

I just had a doubt in my mind. The following subroutine(to search an element, in a list, for example) has a return statement at the end: list *search_list(list *l, item_type x) { if (l == NULL) ...
6
votes
1answer
386 views

Passing a Scala function to a Java 8 method

The following Scala code works and can be passed to a Java method expecting a function. Is there a cleaner way to do this? Here's my first pass: val plusOne = new ...
5
votes
6answers
610 views

Are closures considered impure functional style?

I have a few related questions on closures: Are closures considered impure in functional programming? It seems one can generally avoid closures by passing values directly to a function. Therefore ...
5
votes
2answers
415 views

Function that requires many parameters

I have a problem related to this: Are there guidelines on how many parameters a function should accept? In my case, I have a function that describes a rounded rectangle. The caller specifies An ...
5
votes
3answers
1k views

Static methods or static functions?

I was just reading http://stackoverflow.com/questions/155609/what-is-the-difference-between-a-method-and-a-function and all of a sudden, the thing came to my mind was the static methods. As static ...
5
votes
2answers
131 views

Should more than one function be used when they do similar, but not identical things?

For example, if I wanted to generate some HTML based on some input. Which is the preferred way out of: <?php function generate_html($type, $input){ switch($type){ case 'paragraph': ...
5
votes
2answers
492 views

What can procs and lambdas do that functions can't in ruby

I've been working in Ruby for the last couple weeks, and I've come to the subject of procs, lambdas and blocks. After reading a fair share of examples from a variety of sources, I don't how they're ...
4
votes
6answers
5k views

CoffeeScript and Named Functions

Elsewhere: an argument has arisen over the terminology of a named function in CoffeeScript. In particular somebody refereed to something like this foo = -> console.log("bar") as a named ...
4
votes
3answers
398 views

Renaming long named method in C# [closed]

I'm working on a project where exist one method with title string ValidateNewPasswordExpireCurrentPasswordAndCreateNewPassword(...) I'm sure the method name must be changed. But can't found good ...
4
votes
2answers
879 views

How can “hash functions” be used to implement hash maps at all?

My understandment is that hash maps allow us to link, say, a string, to certain memory location. But if every string were to be linked to a unique place in memory it would need a huge block of empty ...
4
votes
5answers
616 views

Using php functions, reserved words as local identifiers [closed]

I'm thinking of some of the array functions. "key", "each", "pos", "range". These are often very useful as local identifiers! I have also seen code that (ab)uses $return, $list, $array, $string. What ...