default argument

Some other languages, like Java, do not have default arguments.

Default arguments can be seen as a special case of the variable-length argument list.

In other cases a default argument may instead be statically allocated.

Another consideration is the default argument promotions applied to the unnamed arguments.

For example, to have a default argument evaluated to the current time in Python, the following may be used:

Python is a notable language that evaluates expressions in default arguments once, at module load time.

An advantage of tags is that they ease the work with default arguments since the programmer doesn't have to specify them or their substitutes.

If the default argument is explicitly given, then that value is used if it is not provided by the caller.

In computer programming, a default argument is an argument to a function that a programmer is not required to specify.

Know Perl's other default arguments.

Doing so allows the parameters with defaults to optionally be omitted when the function is called, in which case the default arguments will be used.

It is mainly used for abbreviating a system command, or for adding default arguments to a regularly used command.

Unlike in C++, methods in Java are not allowed to have default argument values and methods are usually overloaded instead.

Later languages (for example, in C++) allow the programmer to specify default arguments that always have a value, even if one is not specified when calling the function.

In many cases, specifying default arguments in a single function declaration is preferable to providing overloaded function definitions with different numbers of parameters.

Functions and methods can have default argument values and variable length argument lists and can be called with any order of keyword arguments.

The default argument tags in a 2-sided debate are identical to the side the user posts their argument on, though new tags can be created at users' discretion.

At first, the class, derived class, strong typing, inlining, and default argument features were added to C via Stroustrup's C++ to C compiler, Cfront.

In C++, the standard describes the default constructor for a class as a constructor that can be called with no arguments (this includes a constructor whose parameters all have default arguments).

When a function is called with fewer arguments than there are declared parameters, explicit arguments are matched to parameters in left-to-right order, with any unmatched parameters at the end of the parameter list being assigned their default arguments.

Some programming languages such as Ada, C++, Clojure, Common Lisp, Fortran 90, Python, Ruby, Tcl, and Windows PowerShell allow for a default argument to be explicitly or implicitly given in a subroutine's declaration.

If the default argument is implicit (sometimes by using a keyword such as Optional) then the language provides a well-known value (such as null, Empty, zero, an empty string, etc.) if a value is not provided by the caller.

If a default argument is not simply a literal, but an expression, there is a choice of when the expression is evaluated - once for the entire program (at parse time, compile time, or execution time), or once per function call, at call time.

However, the same behaviour can be simulated by using method overloading to create overloaded methods of the same name, which take different numbers of arguments; and the versions with fewer arguments simply call the versions with more arguments, with the default arguments as the missing arguments:

If evaluation per function call is desired, it can be replicated by having the default argument be a sentinel value, such as in Python, and then in the first line of the function, checking for the sentinel value and assigning to expression if found, which ensures expression evaluation.