Related
This is a language agnostic question, but I'm wandering what people prefer in terms of readability and maintainability... My hypothetical situation is that I'm writing a function which given a sequence will return a copy with all duplicate element removed and the order reversed.
/*
*This is an extremely well written function to return a sequence containing
*all the unique elements of OriginalSequence with their order reversed
*/
ReturnSequence SequenceFunction(OriginalSequence)
{...}
OR
UniqueAndReversedSequence MakeSequenceUniqueAndReversed(OriginalSequence)
{....}
The above is supposed to be a lucid example of using comments in the first instance or using very verbose function names in the second to describe the actions of the function.
Cheers,
Richard
I prefer the verbose function name as it make the call-site more readable. Of course, some function names (like your example) can get really long.
Perhaps a better name for your example function would be ReverseAndDedupe. Uh oh, now it is a little more clear that we have a function with two responsibilities*. Perhaps it would be even better to split this out into two functions: Reverse and Dedupe.
Now the call-site becomes even more readable:
Reverse(Dedupe(someSequence))
*Note: My rule of thumb is that any function that contains "and" in the name has too many responsibilities and needs to be split up in to separate functions.
Personally I prefer the second way - it's easy to see from the function name what it does - and because the code inside the function is well written anyway it'll be easy to work out exactly what happens inside it.
The problem I find with comments is they very quickly go out of date - there's no compile time check to ensure your comment is correct!
Also, you don't get access to the comment in the places where the function is actually called.
Very much a subjective question though!
Ideally you would do a combination of the two. Try to keep your method names concise but descriptive enough to get a good idea of what it's going to do. If there is any possibility of lack of clarity in the method name, you should have comments to assist the reader in the logic.
Even with descriptive names you should still be concise. I think what you have in the example is overkill. I would have written
UniqueSequence Reverse(Sequence)
I comment where there's an explanation in order that a descriptive name cannot adequately convey. If there's a peculiarity with a library that forced me to do something that appears non-standard or value in dropping a comment inline, I'll do that but otherwise I rely upon well-named methods and don't comment things a lot - except while I'm writing the code, and those are for myself. They get removed when it is done, typically.
Generally speaking, function header comments are just more lines to maintain and require the reader to look at both the comment and the code and then decide which is correct if they aren't in correspondence. Obviously the truth is always in the code. The comment may say X but comments don't compile to machine code (typically) so...
Comment when necessary and make a habit of naming things well. That's what I do.
I'd probably do one of these:
Call it ReverseAndDedupe (or DedupeAndReverse, depending which one it is -- I'd expect Dedupe alone to keep the first occurrence and discard later ones, so the two operations do not commute). All functions make some postcondition true, so Make can certainly go in order to shorten a too-long name. Functions don't generally need to be named for the types they operate on, and if they are then it should be in a consistent format. So Sequence can probably be removed from your proposed name too, or if it can't then I'd probably call it Sequence_ReverseAndDedupe.
Not create this function at all, make sure that callers can either do Reverse(Dedupe(x)) or Dedupe(Reverse(x)), depending which they actually want. It's no more code for them to write, so only an issue of whether there's some cunning optimization that only applies when you do both at once. Avoiding an intermediate copy might qualify there, but the general point is that if you can't name your function concisely, make sure there's a good reason why it's doing so many different things.
Call it ReversedAndDeduped if it returns a copy of the original sequence - this is a trick I picked up from Python, where l.sort() sorts the list l in place, and sorted(l) doesn't modify a list l at all.
Give it a name specific to the domain it's used in, rather than trying to make it so generic. Why am I deduping and reversing this list? There might be some term of art that means a list in that state, or some function which can only be performed on such a list. So I could call it 'Renuberate' (because a reversed, deduped list is known as a list "in Renuberated form", or 'MakeFrobbable' (because Frobbing requires this format).
I'd also comment it (or much better, document it), to explain what type of deduping it guarantees (if any - perhaps the implementation is left free to remove whichever dupes it likes so long as it gets them all).
I wouldn't comment it "extremely well written", although I might comment "highly optimized" to mean "this code is really hard to work with, but goes like the clappers, please don't touch it without running all the performance tests".
I don't think I'd want to go as far as 5-word function names, although I expect I have in the past.
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Specific functions vs many Arguments vs context dependent
So I've been developing for 3-4 years now, know a wide range of languages, know some impressive (to the small minded :P ) stuff.
But something I've always wondered; when I make a function should it be for a specific purpose, or should it be moulded to be re-usable, even if I have no need for it to be?
E.G:
//JS, but could be any language really
//specific
function HAL(){
alert("I'm afraid I can't let you do that, " + document.getElementById("Name").value + ".");
}
//generic
function HAL(nme){
alert("I'm afraid I can't let you do that, " + nme + ".");
}
//more generic
function HAL(msg, nme){
alert(msg + " " + nme + ".");
}
Yes, very simple example, but conveys the point I want to make. If we take this example, would I ever use it outside of the first? Probably not, so I'd be tempted to make it this way, but then common sense would (now) convince me to make it the second, yet I can't see any benefit of this way, if I know it's not going to be used in any other way, i.e. It's always going to use the input's value (Yes I would put that into a global variable normally).
Is it just a case of whatever I feel makes the most sense at the time, or should I follow the 2nd pattern as best I can?
In that particular case, I would write the first function for now (YAGNI, right?), and probably never need to change it. Then, if it turned out I did need to support alternate names, I'd make the current behavior the default, but allow an optional parameter to specify a name. Likewise with the message.
# In Ruby, but like you say, could be in anything:
// specific
def hal()
puts "I'm afraid I can't let you do that, #{fetch_name}."
end
// genericized refactoring
def hal( name = fetch_name )
puts "I'm afraid I can't let you do that, #{name}."
end
Typically, that's the approach I prefer to take: create functions at whatever is the most convenient degree of specificity for my current needs, but leave the door open for a more generalized approach later.
It helps that I use languages like Ruby that make this easy, but you can take the same approach to some extent even in Java or C. For example, in Java you might make a specific method with no parameters first, and then later refactor to a more generalized method with a "name" parameter and a no-parameter wrapper that filled in the default name.
A rule of thumb is that a function should have minimal side effects.
So, really, it would look something like this:
//By the way - don't call functions nouns. functions are verbs. data are nouns
void HAL(string s)
{
voicetype_t vt = voice.type();
voice.type(VOICE_OF_DOOM);
voice.say(s);
voice.type(vt);
}
A function shouldn't be just a series of statements to call them in some other context. It should be a unit of functionality that you want to abstract. Making a function to be specific is good, but making it context sensitive is bad. What you should do, is to use the generic way(last one) presented in your post, but provide the messages as constants. The language you use has some way to declare constants right?
In your example, I wouldn't make it generic. If a functionality can be used in many cases, make it generic so you can use it all the time without "copy, paste, make minor change, repeat". But telling the user he can't do that and adressing it as [contents of certain input field] is useful for only one case. Plus, the last shot is pointless.
However, I generally prefer my code to be as generic as feasible. Well, as long as the odds are I will need it one day... let's not violate YANGI too hard. But if it can be generic without hassle, why not?
In my opinion, functions should be genericized only to the extent that their purposes need to be. In other words, you should concede to the fact that, although we want to think differently, not everything is reusable, and thus, you shouldn't go out of your way to implement everything to be like that. Programmers should be conscious of the scope (and possibly the future development) of the product, so ultimately one should use their intuition as to how far to take generalizations of functions.
As for your examples, #3 is completely worthless as it only affixes a space between two strings and appends a period at the end--why would someone do this with a special function? I know that's only an example, but if we're talking about how far to generalize a method, something like that's taking it too far--almost to the point where it's just wasted LOC, and that is never something to sacrifice for the sake of generalizing.
When I'm programming, I often find myself writing functions that -should- (to be proper english) contain apostrophes (too bad C started everyone thinking that an apostrophe was an appropriate delimiter). For example: get_user's_group() -> get_users_group() . What do you guys do with that forced-bad-english ambiguous english? Just ignore the apostrophe? Create a different phrasing?
In that case, I would do get_group_for_user().
So, yes, I would "create a different phrasing" :)
Either that, or user.get_group().
getGroupForUser()
or
getGroupByUser()
My original answer of Ignore it, move on! is incomplete. You should ignore the fact you can't use ' in your method/function names. But you should continue to look at the naming of them to better explain what they do. I think this is a worthwhile pursuit in programming.
Picking on JavaScript, you could if you wanted to use apostrophes:
const user = {
"get_user's_group": () => console.log("Naming things! Am I right?!")
}
user["get_user's_group"]()
But don't do that 😬
Taking it further, you could if you wanted to, use a transpiler to take your grammatically correct name and transform it into something you never see.
Again with JavaScript as an example, maybe you could write a babel transform.
But don't do that 😛
As others have said, if there is context available from an object, that's a nice option:
user.get_group()
Failing that, the context of the surrounding code should be enough to make this your choice:
get_users_group()
How about getGroupByUser?
Either get_user_ApostropheShouldBeHereButLanguageWillNotLetMe_s_group or just ignore it because it really doesn't matter.
I ignore the apostraphe getGroupyUser and group_from_user are both perfectly understandable. Worrying about having correct grammer in your function names is a waste of time and distracts from the correct goal of having clear and understandable user names.
the point of proper english in function naming is a bit extreme ...
i mean why is the apostrophe bothering you but the _ instead of a space is not ?
Depending on the programming language you may be able to use Unicode variable names, this SO thread lists a few.
With Unicode identifiers you could use one of the unicode apostrophes to give the proper english language formatting to your variable name. Though this only speculative. And it would be hard to maintain. Actually, now that I think about it, it sounds downright evil.
Two points: First, don't use a name that would otherwise require an apostrophe if you can avoid it. Second, you are right in being concerned about ambiguity. For example, you could have:
getUsersGroup: gets the group of a list of users. If you are using an object-oriented language, this could have more information than just a group ID string. You could also have something like createUsersGroup, which would create a group object from a list of users passed in.
getGroupOfUser: takes in some sort of user object; returns the name of the group of the user
getGroupByUserId: takes in the user's name or a unique ID associated with that user; returns the name of the group of the user
The best way to delineate the difference between all of these is to just use standard method comments that explain the method names. This would depend on what language you are working with and what style of method comments your organization conventionally uses.
Normally I just drop the apostrophe, but do back-ticks work? (get_user`s_group)
getGroupOfUser? getUserGroup?
It's a programming language, not literature...
It would be getBackgroundColour in proper English (rather than getBackgroundColor)
Personally I'd write get_user_group() rather than get_group_for_user() since it feels like it reads better to me. Of course, I use a programming language where apostrophes are allowed in names:
proc get_user's_group {id} {#...}
Although, some of the more prolific non-English-native European users use it as a word separator:
proc user'group {id} {#...}
to each his own I guess..
Typically languages have keywords that you are unable to use directly with the exact same spelling and case for naming things (variables,functions,classes ...) in your program. Yet sometimes a keyword is the only natural choice for naming something. What is your system for avoiding/getting around this clash in your chosen technology?
I just avoid the name, usually. Either find a different name or change it slightly - e.g. clazz instead of class in C# or Java. In C# you can use the # prefix, but it's horrible:
int #int = 5; // Ick!
There is nothing intrinsically all-encompassing about a keyword, in that it should stop you from being able to name your variables. Since all names are just generalized instances of some type to one degree or another, you can always go up or down in the abstraction to find another useful name.
For example, if your writing a system that tracks students and you want an object to represent their study in a specific field, i.e. they've taken a "class" in something, if you can't use the term directly, or the plural "classes", or an alternative like "studies", you might find a more "instanced" variation: studentClass, currentClass, etc. or a higher perspective: "courses", "courseClass" or a specfic type attribute: dailyClass, nightClass, etc.
Lots of options, you should just prefer the simplest and most obvious one, that's all.
I always like to listen to the users talk, because the scope of their language helps define the scope of the problem, often if you listen long enough you'll find they have many multiple terms for the same underlying things (with only subtle differences). They usually have the answer ...
Paul.
My system is don't use keywords period!
If I have a function/variable/class and it only seems logical to name it with a keyword, I'll use a descriptive word in front of the keyword.
(adjectiveNoun) format. ie: personName instead of Name where "Name" is a keyword.
I just use a more descriptive name. For instance, 'id' becomes identifier, 'string' becomes 'descriptionString,' and so on.
In Python I usually use proper namespacing on my modules to avoid name clashes.
import re
re.compile()
instead of:
from re import *
compile()
Sometimes, when I can't avoid keyword name clashes I simply drop the last letter off the name of my variable.
for fil in files:
pass
As stated before either change class to clazz in Java/C#, or use some underscore as a prefix, for example
int _int = 0;
There should be no reason to use keywords as variable names. Either use a more detailed word or use a thesaraus. Capitalizing certain letters of the word to make it not exactly like the keyword is not going to help much to someone inheriting your code later.
Happy those with a language without ANY keywords...
But joke apart, I think in the seldom situations where "Yet sometimes a keyword is the only natural choice for naming something." you can get along by prefixing it with "my", "do", "_" or similar.
I honestly can't really think of many such instances where the keyword alone makes a good name ("int", "for" and "if" are definitely bad anyway). The only few in the C-language family which might make sense are "continue" (make it "doContinue"), "break" (how about "breakWhenEOFIsreached" or similar ?) and the already mentioned "class" (how about "classOfThingy" ?).
In other words: make the names more reasonable.
And always remember: code is WRITTEN only once, but usualy READ very often.
Typically I follow Hungarian Notation. So if, for whatever reason, I wanted to use 'End' as a variable of type integer I would declare it as 'iEnd'. A string would be 'strEnd', etc. This usually gives me some room as far as variables go.
If I'm working on a particular personal project that other people will only ever look at to see what I did, for example, when making an add-on to a game using the UnrealEngine, I might use my initials somewhere in the name. 'DS_iEnd' perhaps.
I write my own [vim] syntax highlighters for each language, and I give all keywords an obvious colour so that I notice them when I'm coding. Languages like PHP and Perl use $ for variables, making it a non-issue.
Developing in Ruby on Rails I sometime look up this list of reserved words.
In 15 years of programming, I've rarely had this problem.
One place I can immediately think of, is perhaps a css class, and in that case, I'd use a more descriptive name. So instead of 'class', I might use 'targetClass' or something similar.
In python the generally accepted method is to append an '_'
class -> class_
or -> or_
and -> and_
you can see this exemplified in the operator module.
I switched to a language which doesn't restrict identifier names at all.
First of all, most code conventions prevent such a thing from happening.
If not, I usually add a descriptive prose prefix or suffix:
the_class or theClass infix_or (prefix_or(class_param, in_class) , a_class) or_postfix
A practice, that is usually in keeping with every code style advice you can find ("long names don't kill", "Longer variable names don't take up more space in memory, I promise.")
Generally, if you think the keyword is the best description, a slightly worse one would be better.
Note that, by the very premise of your question you introduce ambiguity, which is bad for the reader, be it a compiler or human. Even if it is a custom to use class, clazz or klass and even if that custom is not so custom that it is a custom: it takes a word word, precisely descriptive as word may be, and distorts it, effectively shooting w0rd's precision in the "wrd". Somebody used to another w_Rd convention or language might have a few harsh wordz for your wolds.
Most of us have more to say about things than "Flower", "House" or "Car", so there's usually more to say about typeNames, decoratees, class_params, BaseClasses and typeReferences.
This is where my personal code obfuscation tolerance ends:
Never(!!!) rely on scoping or arcane syntax rules to prevent name clashes with "key words". (Don't know any compiler that would allow that, but, these days, you never know...).
Try that and someone will w**d you in the wörd so __rd, Word will look like TeX to you!
My system in Java is to capitalize the second letter of the word, so for example:
int dEfault;
boolean tRansient;
Class cLass;
What rules do you use to name your variables?
Where are single letter vars allowed?
How much info do you put in the name?
How about for example code?
What are your preferred meaningless variable names? (after foo & bar)
Why are they spelled "foo" and "bar" rather than FUBAR
function startEditing(){
if (user.canEdit(currentDocument)){
editorControl.setEditMode(true);
setButtonDown(btnStartEditing);
}
}
Should read like a narrative work.
One rule I always follow is this: if a variable encodes a value that is in some particular units, then those units have to be part of the variable name. Example:
int postalCodeDistanceMiles;
decimal reactorCoreTemperatureKelvin;
decimal altitudeMsl;
int userExperienceWongBakerPainScale
I will NOT be responsible for crashing any Mars landers (or the equivalent failure in my boring CRUD business applications).
Well it all depends on the language you are developing in. As I am currently using C# I tend you use the following.
camelCase for variables.
camelCase for parameters.
PascalCase for properties.
m_PascalCase for member variables.
Where are single letter vars allows?
I tend to do this in for loops but feel a bit guilty whenever I do so. But with foreach and lambda expressions for loops are not really that common now.
How much info do you put in the name?
If the code is a bit difficult to understand write a comment. Don't turn a variable name into a comment, i.e .
int theTotalAccountValueIsStoredHere
is not required.
what are your preferred meaningless variable names? (after foo & bar)
i or x. foo and bar are a bit too university text book example for me.
why are they spelled "foo" and "bar" rather than FUBAR?
Tradition
These are all C# conventions.
Variable-name casing
Case indicates scope. Pascal-cased variables are fields of the owning class. Camel-cased variables are local to the current method.
I have only one prefix-character convention. Backing fields for class properties are Pascal-cased and prefixed with an underscore:
private int _Foo;
public int Foo { get { return _Foo; } set { _Foo = value; } }
There's some C# variable-naming convention I've seen out there - I'm pretty sure it was a Microsoft document - that inveighs against using an underscore prefix. That seems crazy to me. If I look in my code and see something like
_Foo = GetResult();
the very first thing that I ask myself is, "Did I have a good reason not to use a property accessor to update that field?" The answer is often "Yes, and you'd better know what that is before you start monkeying around with this code."
Single-letter (and short) variable names
While I tend to agree with the dictum that variable names should be meaningful, in practice there are lots of circumstances under which making their names meaningful adds nothing to the code's readability or maintainability.
Loop iterators and array indices are the obvious places to use short and arbitrary variable names. Less obvious, but no less appropriate in my book, are nonce usages, e.g.:
XmlWriterSettings xws = new XmlWriterSettings();
xws.Indent = true;
XmlWriter xw = XmlWriter.Create(outputStream, xws);
That's from C# 2.0 code; if I wrote it today, of course, I wouldn't need the nonce variable:
XmlWriter xw = XmlWriter.Create(
outputStream,
new XmlWriterSettings() { Indent=true; });
But there are still plenty of places in C# code where I have to create an object that you're just going to pass elsewhere and then throw away.
A lot of developers would use a name like xwsTemp in those circumstances. I find that the Temp suffix is redundant. The fact that I named the variable xws in its declaration (and I'm only using it within visual range of that declaration; that's important) tells me that it's a temporary variable.
Another place I'll use short variable names is in a method that's making heavy use of a single object. Here's a piece of production code:
internal void WriteXml(XmlWriter xw)
{
if (!Active)
{
return;
}
xw.WriteStartElement(Row.Table.TableName);
xw.WriteAttributeString("ID", Row["ID"].ToString());
xw.WriteAttributeString("RowState", Row.RowState.ToString());
for (int i = 0; i < ColumnManagers.Length; i++)
{
ColumnManagers[i].Value = Row.ItemArray[i];
xw.WriteElementString(ColumnManagers[i].ColumnName, ColumnManagers[i].ToXmlString());
}
...
There's no way in the world that code would be easier to read (or safer to modify) if I gave the XmlWriter a longer name.
Oh, how do I know that xw isn't a temporary variable? Because I can't see its declaration. I only use temporary variables within 4 or 5 lines of their declaration. If I'm going to need one for more code than that, I either give it a meaningful name or refactor the code using it into a method that - hey, what a coincidence - takes the short variable as an argument.
How much info do you put in the name?
Enough.
That turns out to be something of a black art. There's plenty of information I don't have to put into the name. I know when a variable's the backing field of a property accessor, or temporary, or an argument to the current method, because my naming conventions tell me that. So my names don't.
Here's why it's not that important.
In practice, I don't need to spend much energy figuring out variable names. I put all of that cognitive effort into naming types, properties and methods. This is a much bigger deal than naming variables, because these names are very often public in scope (or at least visible throughout the namespace). Names within a namespace need to convey meaning the same way.
There's only one variable in this block of code:
RowManager r = (RowManager)sender;
// if the settings allow adding a new row, add one if the context row
// is the last sibling, and it is now active.
if (Settings.AllowAdds && r.IsLastSibling && r.Active)
{
r.ParentRowManager.AddNewChildRow(r.RecordTypeRow, false);
}
The property names almost make the comment redundant. (Almost. There's actually a reason why the property is called AllowAdds and not AllowAddingNewRows that a lot of thought went into, but it doesn't apply to this particular piece of code, which is why there's a comment.) The variable name? Who cares?
Pretty much every modern language that had wide use has its own coding standards. These are a great starting point. If all else fails, just use whatever is recommended. There are exceptions of course, but these are general guidelines. If your team prefers certain variations, as long as you agree with them, then that's fine as well.
But at the end of the day it's not necessarily what standards you use, but the fact that you have them in the first place and that they are adhered to.
I only use single character variables for loop control or very short functions.
for(int i = 0; i< endPoint; i++) {...}
int max( int a, int b) {
if (a > b)
return a;
return b;
}
The amount of information depends on the scope of the variable, the more places it could be used, the more information I want to have the name to keep track of its purpose.
When I write example code, I try to use variable names as I would in real code (although functions might get useless names like foo or bar).
See Etymology of "Foo"
What rules do you use to name your variables?
Typically, as I am a C# developer, I follow the variable naming conventions as specified by the IDesign C# Coding Standard for two reasons
1) I like it, and find it easy to read.
2) It is the default that comes with the Code Style Enforcer AddIn for Visual Studio 2005 / 2008 which I use extensively these days.
Where are single letter vars allows?
There are a few places where I will allow single letter variables. Usually these are simple loop indexers, OR mathematical concepts like X,Y,Z coordinates. Other than that, never! (Everywhere else I have used them, I have typically been bitten by them when rereading the code).
How much info do you put in the name?
Enough to know PRECISELY what the variable is being used for. As Robert Martin says:
The name of a variable, function, or
class, should answer all the big
questions. It should tell you why it
exists, what it does, and how it is
used. If a name requires a comment,
then the name does not reveal its
intent.
From Clean Code - A Handbook of Agile Software Craftsmanship
I never use meaningless variable names like foo or bar, unless, of course, the code is truly throw-away.
For loop variables, I double up the letter so that it's easier to search for the variable within the file. For example,
for (int ii=0; ii < array.length; ii++)
{
int element = array[ii];
printf("%d", element);
}
What rules do you use to name your variables? I've switched between underscore between words (load_vars), camel casing (loadVars) and no spaces (loadvars). Classes are always CamelCase, capitalized.
Where are single letter vars allows? Loops, mostly. Temporary vars in throwaway code.
How much info do you put in the name? Enough to remind me what it is while I'm coding. (Yes this can lead to problems later!)
what are your preferred meaningless variable names? (after foo & bar) temp, res, r. I actually don't use foo and bar a good amount.
What rules do you use to name your variables?
I need to be able to understand it in a year's time. Should also conform with preexisting style.
Where are single letter vars allows?
ultra-obvious things. E.g. char c; c = getc(); Loop indicies(i,j,k).
How much info do you put in the name?
Plenty and lots.
how about for example code?
Same as above.
what are your preferred meaningless variable names? (after foo & bar)
I don't like having meaningless variable names. If a variable doesn't mean anything, why is it in my code?
why are they spelled "foo" and "bar" rather than FUBAR
Tradition.
The rules I adhere to are;
Does the name fully and accurately describe what the variable represents?
Does the name refer to the real-world problem rather than the programming language solution?
Is the name long enough that you don't have to puzzle it out?
Are computed value qualifiers, if any, at the end of the name?
Are they specifically instantiated only at the point once required?
What rules do you use to name your variables?
camelCase for all important variables, CamelCase for all classes
Where are single letter vars allows?
In loop constructs and in mathematical funktions where the single letter var name is consistent with the mathematical definition.
How much info do you put in the name?
You should be able to read the code like a book. Function names should tell you what the function does (scalarProd(), addCustomer(), etc)
How about for example code?
what are your preferred meaningless variable names? (after foo & bar)
temp, tmp, input, I never really use foo and bar.
I would say try to name them as clearly as possible. Never use single letter variables and only use 'foo' and 'bar' if you're just testing something out (e.g., in interactive mode) and won't use it in production.
I like to prefix my variables with what they're going to be: str = String, int = Integer, bool = Boolean, etc.
Using a single letter is quick and easy in Loops: For i = 0 to 4...Loop
Variables are made to be a short but descriptive substitute for what you're using. If the variable is too short, you might not understand what it's for. If it's too long, you'll be typing forever for a variable that represents 5.
Foo & Bar are used for example code to show how the code works. You can use just about any different nonsensical characters to use instead. I usually just use i, x, & y.
My personal opinion of foo bar vs. fu bar is that it's too obvious and no one likes 2-character variables, 3 is much better!
In DSLs and other fluent interfaces often variable- and method-name taken together form a lexical entity. For example, I personally like the (admittedly heretic) naming pattern where the verb is put into the variable name rather than the method name. #see 6th Rule of Variable Naming
Also, I like the spartan use of $ as variable name for the main variable of a piece of code. For example, a class that pretty prints a tree structure can use $ for the StringBuffer inst var. #see This is Verbose!
Otherwise I refer to the Programmer's Phrasebook by Einar Hoest. #see http://www.nr.no/~einarwh/phrasebook/
I always use single letter variables in for loops, it's just nicer-looking and easier to read.
A lot of it depends on the language you're programming in too, I don't name variables the same in C++ as I do in Java (Java lends itself better to the excessively long variable names imo, but this could just a personal preference. Or it may have something to do with how Java built-ins are named...).
locals: fooBar;
members/types/functions FooBar
interfaces: IFooBar
As for me, single letters are only valid if the name is classic; i/j/k for only for local loop indexes, x,y,z for vector parts.
vars have names that convey meaning but are short enough to not wrap lines
foo,bar,baz. Pickle is also a favorite.
I learned not to ever use single-letter variable names back in my VB3 days. The problem is that if you want to search everywhere that a variable is used, it's kinda hard to search on a single letter!
The newer versions of Visual Studio have intelligent variable searching functions that avoid this problem, but old habits and all that. Anyway, I prefer to err on the side of ridiculous.
for (int firstStageRocketEngineIndex = 0; firstStageRocketEngineIndex < firstStageRocketEngines.Length; firstStageRocketEngineIndex++)
{
firstStageRocketEngines[firstStageRocketEngineIndex].Ignite();
Thread.Sleep(100); // Don't start them all at once. That would be bad.
}
It's pretty much unimportant how you name variables. You really don't need any rules, other than those specified by the language, or at minimum, those enforced by your compiler.
It's considered polite to pick names you think your teammates can figure out, but style rules don't really help with that as much as people think.
Since I work as a contractor, moving among different companies and projects, I prefer to avoid custom naming conventions. They make it more difficult for a new developer, or a maintenance developer, to become acquainted with (and follow) the standard being used.
So, while one can find points in them to disagree with, I look to the official Microsoft Net guidelines for a consistent set of naming conventions.
With some exceptions (Hungarian notation), I think consistent usage may be more useful than any arbitrary set of rules. That is, do it the same way every time.
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I work in MathCAD and I'm happy because MathCAD gives me increadable possibilities in naming and I use them a lot. And I can`t understand how to programm without this.
To differ one var from another I have to include a lot of information in the name,for example:
1.On the first place - that is it -N for quantity,F for force and so on
2.On the second - additional indices - for direction of force for example
3.On the third - indexation inside vector or matrix var,for convinience I put var name in {} or [] brackets to show its dimensions.
So,as conclusion my var name is like
N.dirs / Fx i.row / {F}.w.(i,j.k) / {F}.w.(k,i.j).
Sometimes I have to add name of coordinate system for vector values
{F}.{GCS}.w.(i,j.k) / {F}.{LCS}.w.(i,j.k)
And as final step I add name of the external module in BOLD at the end of external function or var like Row.MTX.f([M]) because MathCAD doesn't have help string for function.
Use variables that describes clearly what it contains. If the class is going to get big, or if it is in the public scope the variable name needs to be described more accurately. Of course good naming makes you and other people understand the code better.
for example: use "employeeNumber" insetead of just "number".
use Btn or Button in the end of the name of variables reffering to buttons, str for strings and so on.
Start variables with lower case, start classes with uppercase.
example of class "MyBigClass", example of variable "myStringVariable"
Use upper case to indicate a new word for better readability. Don't use "_", because it looks uglier and takes longer time to write.
for example: use "employeeName".
Only use single character variables in loops.
Updated
First off, naming depends on existing conventions, whether from language, framework, library, or project. (When in Rome...) Example: Use the jQuery style for jQuery plugins, use the Apple style for iOS apps. The former example requires more vigilance (since JavaScript can get messy and isn't automatically checked), while the latter example is simpler since the standard has been well-enforced and followed. YMMV depending on the leaders, the community, and especially the tools.
I will set aside all my naming habits to follow any existing conventions.
In general, I follow these principles, all of which center around programming being another form of interpersonal communication through written language.
Readability - important parts should have solid names; but these names should not be a replacement for proper documentation of intent. The test for code readability is if you can come back to it months later and still be understanding enough to not toss the entire thing upon first impression. This means avoiding abbreviation; see the case against Hungarian notation.
Writeability - common areas and boilerplate should be kept simple (esp. if there's no IDE), so code is easier and more fun to write. This is a bit inspired by Rob Pyke's style.
Maintainability - if I add the type to my name like arrItems, then it would suck if I changed that property to be an instance of a CustomSet class that extends Array. Type notes should be kept in documentation, and only if appropriate (for APIs and such).
Standard, common naming - For dumb environments (text editors): Classes should be in ProperCase, variables should be short and if needed be in snake_case and functions should be in camelCase.
For JavaScript, it's a classic case of the restraints of the language and the tools affecting naming. It helps to distinguish variables from functions through different naming, since there's no IDE to hold your hand while this and prototype and other boilerplate obscure your vision and confuse your differentiation skills. It's also not uncommon to see all the unimportant or globally-derived vars in a scope be abbreviated. The language has no import [path] as [alias];, so local vars become aliases. And then there's the slew of different whitespacing conventions. The only solution here (and anywhere, really) is proper documentation of intent (and identity).
Also, the language itself is based around function level scope and closures, so that amount of flexibility can make blocks with variables in 2+ scope levels feel very messy, so I've seen naming where _ is prepended for each level in the scope chain to the vars in that scope.
I do a lot of php in nowadays, It was not always like that though and I have learned a couple of tricks when it comes to variable naming.
//this is my string variable
$strVar = "";
//this would represent an array
$arrCards = array();
//this is for an integer
$intTotal = NULL:
//object
$objDB = new database_class();
//boolean
$blValid = true;