Opinions about underscores in names

[Kari Laitinen]

During the past 15 years I have been writing computer
programs with so-called natural names, which means
that the names (identifiers, symbols) in progarms
are constructed of several natural words. I have even
written a C++ book in which all programs are written
with natural names. More information and free pages
of the book can be found at
http://www.naturalprogramming.com/cppbook.html

I'm planning to produce similar books with the C# and
Java programming languages, but there is one thing
related to naming of which I would like to hear opinions.

In the C++ world it is common to separate the words
of a long name with underscore characters. These kinds
of names look like

integer_from_keyboard
find_largest_number_in_array
character_index
file_to_be_copied

In the Java and C# worlds, it is common to use capitalization
to mark the beginning of a new word in a name. If the above
names would appear in a Java program, they would look like

integerFromKeyboard
findLargestNumberInArray
characterIndex
fileToBeCopied

The naming style in which the first word is not capitalized
and the following words are capitalized is called camel casing,
obviously because the names look a little bit like camels.

I have been thinking which names, the names with underscores or
the camel-cased names, are more readable and natural. I have
tried programming with both styles, and my own conclusion is that
the C++ -style names with underscores are more readable. It is
easier to read them because the words are clearly separated
with underscores. The underscores leave empty space between words,
and that is what we are accustomed to when reading "natural
texts". OrDoYouThinkThatThisSentenceIsReadable?

I would like to hear your opinions about this matter. So my
question is: Which way to mark the beginning of a new word
in a long name makes the names most readable?

Please note that I'm not asking opinions about the idea of
natural naming. I'm asking opinions about how words should
be separated in a long natural name. If you want to know
why I'm too much interested in names in programs, please
read the freely available epilogue of the above-mentioned
book.

 

[Michael Winter]

on 13/11/2003:

During the past 15 years I have been writing computer
programs with so-called natural names, which means
that the names (identifiers, symbols) in progarms
are constructed of several natural words. I have even
written a C++ book in which all programs are written
with natural names. More information and free pages
of the book can be found at
http://www.naturalprogramming.com/cppbook.html

I'm planning to produce similar books with the C# and
Java programming languages, but there is one thing
related to naming of which I would like to hear opinions.

In the C++ world it is common to separate the words
of a long name with underscore characters. These kinds
of names look like

integer_from_keyboard
find_largest_number_in_array
character_index
file_to_be_copied

In the Java and C# worlds, it is common to use capitalization
to mark the beginning of a new word in a name. If the above
names would appear in a Java program, they would look like

integerFromKeyboard
findLargestNumberInArray
characterIndex
fileToBeCopied

The naming style in which the first word is not capitalized
and the following words are capitalized is called camel casing,
obviously because the names look a little bit like camels.

I have been thinking which names, the names with underscores or
the camel-cased names, are more readable and natural. I have
tried programming with both styles, and my own conclusion is that
the C++ -style names with underscores are more readable. It is
easier to read them because the words are clearly separated
with underscores. The underscores leave empty space between words,
and that is what we are accustomed to when reading "natural
texts". OrDoYouThinkThatThisSentenceIsReadable?

I would like to hear your opinions about this matter. So my
question is: Which way to mark the beginning of a new word
in a long name makes the names most readable?

Please note that I'm not asking opinions about the idea of
natural naming. I'm asking opinions about how words should
be separated in a long natural name. If you want to know
why I'm too much interested in names in programs, please
read the freely available epilogue of the above-mentioned
book.

This subject has been discussed quite extensively in the
comp.programming newsgroup. The title of the thread there is "ISO
Studies of underscores vs MixedCase in Ada or C++". It was started
some time ago, you may need to use an archive (such as Google groups)
to read it all. I lost track quite some time ago, so I don't know the
current direction of the thread.

There is also an earlier thread in this group called
"thisIsAMemberFunctionName vs this_is_a_member_function_name" on the
same subject.

Mike

 

[Ekkehard Morgenstern]

Hi Kari Laitinen,

I would like to hear your opinions about this matter. So my
question is: Which way to mark the beginning of a new word
in a long name makes the names most readable?

In my opinion, it depends on what type of code you're working on.

If you don't want to spend a lot of time typing, it might be more convenient
using shorter names, with or without capitalization.

Readability matters foremost when many people are working on the same piece
of code.

You might also want to have a look at other naming schemes, like that
endorsed by Microsoft, which recommends class data members beginning with
"m_" (for member), followed by a type identifier, followed by a capitalized
name. For example, "m_iCurrentMileage" would denote an integer named
"CurrentMileage" as a class member.

Readability might also depend on the issue whether you capitalize the names
of member functions. Like "ParkCar" might be more readable in expressions
like "myCar.ParkCar()" than "my_car.park_car()", especially when you have a
lot of dereferentiations, as in
'blue_window->entry_field["account_number"]->set_foreground_color(
public_color_table->get_color_value_for_color( "marine_blue" ) );' instead
of 'blueWindow->entryField["account#"]->setFgCol(
pubColTab->GetColor("marineblue") );'

If in complex expressions, program lines become too long, so that they have
to be split over several lines, the readability of the code might suffer
more than when using shorter, capitalized names.

If I don't have to follow specific guidelines, I always use the type of
notation that seems more convenient to me and the task at hand.

I hope that helps.

Regards,
Ekkehard Morgenstern.