15.8 Which File Defined a Certain Symbol

Function: symbol-file symbol &optional type

This function returns the name of the file that defined symbol. If type is nil, then any kind of definition is acceptable. If type is defun, defvar, or defface, that specifies function definition, variable definition, or face definition only.

The value is normally an absolute file name. It can also be nil, if the definition is not associated with any file. If symbol specifies an autoloaded function, the value can be a relative file name without extension.

The basis for symbol-file is the data in the variable load-history.

Variable: load-history

The value of this variable is an alist that associates the names of loaded library files with the names of the functions and variables they defined, as well as the features they provided or required.

Each element in this alist describes one loaded library (including libraries that are preloaded at startup). It is a list whose CAR is the absolute file name of the library (a string). The rest of the list elements have these forms:

var

The symbol var was defined as a variable.

(defun . fun)

The function fun was defined.

(t . fun)

The function fun was previously an autoload before this library redefined it as a function. The following element is always (defun . fun), which represents defining fun as a function.

(autoload . fun)

The function fun was defined as an autoload.

(defface . face)

The face face was defined.

(require . feature)

The feature feature was required.

(provide . feature)

The feature feature was provided.

The value of load-history may have one element whose CAR is nil. This element describes definitions made with eval-buffer on a buffer that is not visiting a file.

The command eval-region updates load-history, but does so by adding the symbols defined to the element for the file being visited, rather than replacing that element. See Eval.