Functions in Typed Languages

The @deftypefn command and its variations are for describing functions in languages in which you must declare types of variables and functions, such as C and C++.

@deftypefn category data-type name arguments...

The @deftypefn command is the general definition command for functions and similar entities that may take arguments and that are typed. The @deftypefn command is written at the beginning of a line and is followed on the same line by the category of entity being described, the type of the returned value, the name of this particular entity, and its arguments, if any.

For example,

          @deftypefn {Library Function} int foobar
            (int @var{foo}, float @var{bar})
          ...
          @end deftypefn
          

(where the text before the "...", shown above as two lines, would actually be a single line in a real Texinfo file) produces the following in Info:

          -- Library Function: int foobar (int FOO, float BAR)
          ...
          

This means that foobar is a "library function" that returns an int, and its arguments are foo (an int) and bar (a float).

The argument names that you write in @deftypefn are not subject to an implicit @var--since the actual names of the arguments in @deftypefn are typically scattered among data type names and keywords, Texinfo cannot find them without help. Instead, you must write @var explicitly around the argument names. In the example above, the argument names are foo and bar.

The template for @deftypefn is:

          @deftypefn category data-type name arguments ...
          body-of-description
          @end deftypefn
          

Note that if the category or data type is more than one word then it must be enclosed in braces to make it a single argument.

If you are describing a procedure in a language that has packages, such as Ada, you might consider using @deftypefn in a manner somewhat contrary to the convention described in the preceding paragraphs.

For example:

          @deftypefn stacks private push
                 (@var{s}:in out stack;
                 @var{n}:in integer)
          ...
          @end deftypefn
          

(The @deftypefn arguments are shown split into three lines, but would be a single line in a real Texinfo file.)

In this instance, the procedure is classified as belonging to the package stacks rather than classified as a `procedure' and its data type is described as private. (The name of the procedure is push, and its arguments are s and n.)

@deftypefn creates an entry in the index of functions for name.

@deftypefun data-type name arguments...

The @deftypefun command is the specialized definition command for functions in typed languages. The command is equivalent to @deftypefn Function ....

Thus,

          @deftypefun int foobar (int @var{foo}, float @var{bar})
          ...
          @end deftypefun
          

produces the following in Info:

          -- Function: int foobar (int FOO, float BAR)
          ...
          

The template is:

          @deftypefun type name arguments...
          body-of-description
          @end deftypefun
          

@deftypefun creates an entry in the index of functions for name.