Beginning variable names with the prefix 'the' [closed] - prefix

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Okay, this one is pretty hard to google.
Occasionally, I stumble upon code in any language that uses a naming convention where variable names start with the prefix 'the' under certain circumstances.
I could not figure out, however, what these circumstances are. So my questions are:
Is this convention common? Does it have a name?
If 1) is still "ungoogleable": What are the principles behind this convention? What problems does it address? I would like to understand.
If not covered by 1) and 2): Where does the convention come from? What are its origins? Is or was it connected to a specific programming language?
Examples:
From the Steinberg ASIO SDK 2.3, file asiodrivers.cpp, line 88:
extern IASIO* theAsioDriver;
where IASIO is an interface definition.
http://hl7api.sourceforge.net/base/apidocs/src-html/ca/uhn/hl7v2/util/StringUtil.html
http://xml.apache.org/xalan-c/apiDocs/classXStringAllocator.html
http://www.cplusplus.com/forum/beginner/65050/
http://www.cise.ufl.edu/~sahni/dsaac/enrich/c20/fold2.htm
I am hoping for some insight into why people do this. One example might be to tell parameters from members in setter/getter methods, but this choice of prefix seems random to me.

Answer 1

The only time I would be tempted to start a variable name with the would be to indicate that it is a singleton. Other than that its use seems unnecessary.

Answer 2

Based on personal experience (mostly Java, Ruby, Python, and long ago C and C++), the convention you describe is not common.
There is a related convention, the "Type Suggesting Parameter Name" pattern in Kent Beck's "Smalltalk Best Practice Patterns" (an excellent book regardless of whether you write Smalltalk), which names method parameters a(type) or an(type), e.g. anObject. My understanding is that this convention is to make code read a little more like English, not to avoid any naming collision that might otherwise arise. (Smalltalk classes are capitalized, so one could name parameters with downcased class names and there would be no collision.)
An expanded version of this convention which I saw somewhere prefixed parameters or locals with a or an and object instance variables with the, which makes some sense: the instance variable is "the" one most important to the containing object, while the parameter or local is just "a" thing. I wish I could remember where I saw it. I think it was written by a well-known author.
I don't normally use these conventions myself; instead I (like most code I've seen) use this. in Java and self. in Ruby to disambiguate instance variables and rely on short methods to sidestep the need to disambiguate parameters and locals. Naming variables for their roles and not their types (the best practice in any case) also usually eliminates the need for such conventions.
However, inspired by whatever it was I once read, I use the when a local shadows a method or function and I just can't think of a different meaningful name for the local.
In Ruby, a local shadows a method only when the method has no arguments:
def foo
7
end
foo = foo
=> nil # the left hand side shadowed the right hand side
This can be avoided by calling the method with empty parentheses:
def foo
7
end
foo = foo()
=> 7
but empty parentheses seem so un-Ruby to me that I prefer "the":
def foo
7
end
the_foo = foo
=> 7
In Python a local can shadow a function regardless of the function's argument count, so I find myself reaching for the more often.