A singleton variable, in computer programming, is Variable that is referred to only once in a piece of code, probably because of a programming mistake. To be useful, a variable must be set and read from, in that order. If it is only referred to once then it cannot be both set and read.
There are various exceptions. C_programming_language-like assignment operators, e.g. x += y , read and set x and return its new value (they are abbreviations for x = x+y , etc). A function argument may be passed only for the sake of uniformity or to support future enhancements. A good
Compiler or a syntax checker like Lint programming tool should report singleton variables but also allow specific instances to be marked as deliberate by the programmer.