I see a lot of different styles of variable names used in different kind of languages. Sometimes these names are lowercase and using underscores (i.e. test_var) and other times I see variables like testVar.
Is there a specific reason why programmers use different variable name styles in different languages?
It's really just the convention for that programming language.
For example, most Java programs use camel-casing (testVar) while a lot of C programs use _ to seperate words (test_var).
It's completely the choice of the programmer, but most languages have "standard" naming conventions.
As Wiki says :
Reasons for using a naming convention (as opposed to allowing programmers to choose any character sequence) include the following:
to reduce the effort needed to read and understand source code;1
to enhance source code appearance (for example, by disallowing overly long names or abbreviations).
Also there are code conventions in companies that care about readability of their code.
This simplify the code sharing between programmers and they don't spend time to understand what means variables name "aaa" and "bbb".
There is no real reason. Each language and sometimes even platform can have varying naming conventions.
For instance, in .Net TestVar would be seen if it was a public class variable. In C++, testVar would probably be opted for. In Ruby, test_var, etc. It's just a matter of preference by the community and/or creators.
I urge you to follow language standards. I work on a team that has had many developers working on the code over the years, and very few standards have been followed. The majority of our code is nearly unreadable. I have been working on a standardization project for the last several months. It has been very difficult to enforce and get buy-in. I'm hopeful that people will come around as they start seeing the benefits of easy to read code.
For naming conventions/standards keep this in mind:
Follow team/company standards
Follow language standards
Follow the style that the program is already using
Do whatever you want (Not really - if you don't have standards follow
your language standards/conventions.)
Related
Can someone direct me to online resources for designing and implementing abstract semantic graphs (ASG)? I want to create an ASG editor for my language. Being able to edit the ASG directly has a number of advantages:
Only identifiers and literals need to be typed in and identifiers are written only once, when they're defined. Everything else is selected via the mouse.
Since the editor knows the language's grammar, there are no more syntax errors. The editor prevents them from being created in the first place.
Since the editor knows the language's semantics, there are no more semantic errors.
There are some secondary advantages:
Since all the reserved words are easily separable, a program can be written in one locale and viewed in other. On-the-fly changes of locale are possible.
All the text literals are easily separable, so changes of locale are easily made, including on-the-fly changes.
I'm not aware of a book on the matter, but you'll find the topic discussed in portions of various books on computer language. You'll also find discussions of this surrounding various projects which implement what you describe. For instance, you'll find quite a bit of discussion regarding the design of Scratch. Most workflow engines are also based on scripting in semantic graphs.
Allow me to opine... We've had the technology to manipulate language structurally for basically as long as we've had programming languages. I believe that the reason we still use textual language is a combination of the fact that it is more natural for us as humans, who communicate in natural language, to wield, and the fact that it is sometimes difficult to compose and refactor code when proper structure has to be maintained. If you're not sure what I mean, try building complex expressions in Scratch. Text is easier and a decent IDE gives virtually as much verification of correct structure.*
*I don't mean to take anything away from Scratch, it's a thing of beauty and is perfect for its intended purpose.
I hope this doesn't get closed due to being too broad. I know it comes down to personal preference, but there is an origin to all casing conventions and I would like to know where this one came from and a logical explanation as to why people use it.
It's where you go all like var empName;. I call that lower camel, although it's probably technically called something else. Personally, I go like var EmpName. I call that proper camel and I like it.
When I first started programming, I began with the lower camel convention. I didn't know why. I just followed the examples set by all the old guys. Variables and functions (VB) got lower camel while subs and properties got proper camel. Then, after I finally acquired a firm grasp on programming itself, I became comfortable enough to question the tactics of my mentors. It didn't make logical sense to me to use lower camel because it wasn't consistent, especially if you have a variable that consists of one word which ends up being in all lowercase. There is also no validation mechanism in place to make sure you are appropriately using lower vs. upper camel, so I asked why not just use proper camel for everything. It's consistent since all variable names are subject to proper camelization.
Having dug deeper into it, it turns out that this is a very sensitive issue to many programmers when it is brought to question. They usually answer with, "Well, it's just personal preference" or "That's just how I learned it". Upon prodding further, it usually invokes a sort of dogmatic reaction with the person as I attempt to find a logical reason behind their use of lower camel.
So anyone want to shed a little history and logic behind casing of the proper camelatory variety?
It's a combination of two things:
The convention of variables starting with lower case, to differentiate from classes or other entities which use a capital. This is also sometimes used to differentiate based on access level (private/public)
CamelCasing as a way to make multi-word names more readable without spaces (of course this is a preference over underscore, which some people use). I would guess the logic is that CamelCasing is easier/faster for some to type than word_underscores.
Whether or not it gets used is of course up to whomever is setting the coding standards that govern the code being written. Underscores vs CamelCase, lowercasevariables vs Uppercasevariables. CamelCase + lowercasevariable = camelCase
In languages like C# or VB, the standard is to start private things with lowercase and start public/protected things with uppercase. This way, just by looking at the first letter you can tell whether the thing you are messing could be used by other classes and thus any changes need more scrutiny. Also, there are tools to enforce naming conventions like this. The one created/used internally at Microsoft is called StyleCop and is available as a free download.
Historically, well named variables in C (a case-sensitive language) consisted of a single word in lower case. UPPERCASE was reserved for macros.
Then came along C++, where classes are usually CapitalizedAndCamelCased, and variables/functions consisting of several words are camelCased. (Note that C people tend to dislike camelCase, and instead write identifiers_this_way.
From there, it spread.
And, yes, probably other case-sensitive languages have had some influence.
lowerCamelCase I think has become popular because of java and javascript.
In java, it is specifically defined why, that the first word should be a verb with small letters where the remaining words start with a capital letter.
The reason why java chose lowerCamelCase I think depends on what they wanted to solve. Java was launched in 1995 as a language that would make programming easy. C/C++ that was often used was often considered difficult and too technical.
This was something java claimed to solve, more people would be able to program and the same code would work on different hardware. The code was the documentation, you didn't need to comment code, just read and everything would be great.
lowerCamelCase makes it harder to write "technical" code because it removes options to use uppercase and lowercase letters to better describe the code from a technical perspective. Java didn't want to be hard, java was the language to use where everyone could learn to program.
javascript in browsers was created in 10 days by Brendan Eich in 1995. Why javascript selected lowerCamelCase I think is because of java. It has nothing to do with java but it has "java" in its name "javascript".
Objective-C doesn't have namespaces, and many (such as CocoaDevCentral's Cocoa Style Guide) recommend prefixing your class names with initials to avoid namespace collision.
Quoting from the above link:
Objective-C doesn't have namespaces,
so prefix your class names with
initials. This avoids "namespace
collision," which is a situation where
two pieces of code have the same name
but do different things.
That makes sense, I suppose. But honestly, in the context of a relatively small app (say, an iPhone game), is this really an issue? Should I really rename MyViewController to ZPViewController? If not, at what point do namespace collisions really become a concern?
If you're writing an application that uses some set of libraries, then you already know what your namespace looks like and you just need to select names that do not conflict with existing available functions.
However, if you are writing a library for use by others, then you should pick a reasonably unique prefix to try to avoid name collisions with other libraries. With only two characters there may still be name collisions, but the frequency will be reduced.
Small apps shouldn't use up all the good names, so won't have a problem with namespaces.
But it is a good idea to get used to the style that languages are generally written in. It makes it easier to read other people's code, and for others to read yours.
E. g., use camelCase variables in Java, but CamelCase vars in C#, hyphen_separated_names in C, etc.
It will make it easier for you to learn in the long run.
I have read (but haven't verified) that Apple has private classes in their frameworks that don't include any prefixes on the names. So if your application classes' names have no prefixes, you risk colliding with those.
I've worked with repositories where classes were not prefixed. (Or only some of the classes were prefixed.)
One thing that I found painful is it's sometimes hard to tell if code was written by someone inside or outside the company. Using a consistent prefix makes it immediately obvious for someone reading the code for the first time.
Keep in mind that code will be read many more times than written.
Also, it can definitely come in handy when using tools like grep and sed.
what is the best way to declare variable names.... in uppercase ...? .. lowercase? in which area must be declared in any case ... and what name is appropriate depending on the roll of the standard variable ... there are some variables to declare?...sorry for the question..I'm new to the world of programming ... I hope not bother .... =)
Well here are some links for the coding standards for various languages..
This has standards for variable naming and a lot more.
C# coding standards
C++ coding standards
Java coding standards
And here is generic coding standards article that explains the reasoning behind the coding standards.
Atleast for C and C++ we can use Hungarian notation
If:
the language doesn't dictate it; and
your coding standards don't dictate it,
then just make it as readable as possible. Hordes of developers in the future will sing praises to your name for not inflicting horrible code on them.
My personal favorite is all uppercase and underscores for constants (IQ_LIMIT) and camel case for everything else (getItembyId(), itemCount). But that's personal preference, not something written on stone tablets.
It really depends on the programming language you use, and any coding conventions that are followed by a group.
For example, there is the GNU coding standards for writing C code which covers variable names down to the indentation of lines.
For languages, the Code Conventions for the Java Programming Language lays out some coding conventions for capitalization and naming of variables, packages, classes, methods, etc in the Java programming language.
When in Rome, do as the Romans. Each language usually has its own idioms with respect to these sorts of things.
IMO, knowing the scope of a variable is the most important thing. You should know at a glance how much code can effect a variable and how much code will be effected by your changing it. In this way encapsulation (and your sanity) can be maintained. You won't accidentally change a global variable and mysteriously hose the whole program. Also they should stand out like a sore thumb just begging to be refactored away.
Therefore upper-case the first letter for globals (where "global" is any variable that can be seen by more than one function) and lower-case the first letter for every else. Constants traditionally get all caps.
So in studlyCaps style it would be:
GlobalVariable
localVariable
CONSTANTVARIABLE
And using under scores:
Global_Variable
local_variable
CONSTANT_VARIABLE
Whether you use studlyCaps or under scores depends on your programming language and local style (I prefer under scores for their readability and no confusion about capitalization).
In C#, we use PascalCase for properties and methodnames and camelCase for other members. For constants we use CAPS_WITH_UNDERSCORE. For the html elements hungarian notation is used. (I think these are Microsoft standards.)
A corollary to "When in Rome..." is to do as the previous coder has done. When you are working on another developers code or project, you should match your style to the existing style. While seeing a weird convention is puzzling and hard to deal with at first, it is nothing compared to sorting out a file that switches notation and style every couple of functions.
When working on your own project, or as a single developer you can do what is most comfortable within reason.
After switching back and forth between several scripting languages this week, I found myself thinking how similar they all are. Yet I'm always reaching for Google (or nowadays SO) to remember details like what the local equivalents of "instanceof" and "endswith" are, or the right syntax to declare an interface, or whatever.
This reminded me of the (human) language Europonto. Just pick some vaguely English syntax and some vaguely Romance/Germanic/Slavic vocabulary, and it's all good!
So what would happen if we tried to do the same thing with a scripting language. In the mood for Python-style indented blocks today? Fine! Want to use a prototype object? Ok! Can only remember how to spell the PHP names of some library function? No problem!
Anyway, that's the wild and crazy idea. Since we need a question that admits concrete answers, let's tighten it up like this:
What would be the most significant conflicts in creating a scripting language that permitted all the native syntax and library functions of [Python, Ruby, PHP, Perl, shell, and JavaScript], such that you could freely intermix code blocks and function names between languages?
And let's say that any particular construction should be consistent at the statement level. So we'll allow:
foreach( $foo as $bar )
{
if $foo == 2:
print "hi"
}
but not, say,
foreach( $foo as $bar )
{
if $foo == 2:
print "hi"
endif
end
Conflicts can include: parser ambiguities; name collision; conflicting semantics for objects or functions or closures; etc. I'm guessing that scope will be a ginormous issue, but you tell me.
I'll start this as "community wiki" from the get go, so if you think it's a fun question but want to make it more rigorous, feel free to edit.
I would suggest that the main problem is recognising what the syntax of each statement is supposed to be.
In any case, what is the point? Almost all scripting languages have facilities to do much the same things, which is why people tend to master one that they use consistently, and stick with it.
The main difficulty would to be to allow people maintain it. With a well defined language you can only print a certain way and do sys.argv a certain way. once you allow multiple syntaxes there is no sane way to search for all the sys.argv in the code base you have.
At the syntactical level the only problem I can see would be to detect which block has which syntax, then separate them and parse them with specific parsers. Of course given very small statements there could be ambiguities as to which language it is and you could argue that it doesn't matter, but it just may be the case, that in different languages the same string of characters does different things so this could be a subtle issue.
At the API level you would have lots of different methods of doing the same thing but in a subtly different way or subset of doing it. So for example you could have no way of doing Java's string.startsWith() in let's say PHP, so you would do something different, or no way of doing PHP's strstr() (which returns a part of the string from the found needle to the end) and you would implement something different for that or even think differently about the problem. Then you would have to have all those different API methods of doing the same things and that would be huge API to implement, support and (god forbid) learn.
At the wetware level the code written by others would be totally unreadable unless you know a ton of languages and their subtle differences. I think it is difficult enough to learn a single programming language to the smallest details and so it is not practical at all to have this kind of frankensteinish beast created. I can think of an exception for use as an algorithm description language which it already is used in universities all over the world, where teacher takes some language of his liking and makes the code as readable as it can be for a human without needing to implement a parser for it.
As a side note I think this kind of system could be implemented at the least effort by somehow utilizing .NET's CLR where you have a ton of different languages each compiling to the same bytecode and accessing the same variables and stuff. All you'd need to do is split the code to clusters of different languages, then compile them separately on their respective compilers and then just merge the bytecode and somehow make sure they all point to the same variables and functions when mentioning the same names across the different languages.
I have begun to see that syntax is but one property of a language. And most of them look like C to me. The purpose of a language (object oriented, strong typing, etc) is something else again. It starts to look like syntax is not the most important aspect.
I went and read the wikipedia entry...
Europanto is a linguistic jest presented as a "constructed language" with a hodge-podge vocabulary
"Hodge-podge" sounds like the way Perl has been described to me!
I found a rather detailed discussion of closures in Ruby. It sounds like getting Ruby's behavior to coexist with JavaScript's or Python's would require some kind of ugly disambiguation.
If anybody were to add Perl to the list of languages to be covered, I think its lexical scoping rules would present a related problem?