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add-file-hook(2)
add-file-hook(2)add-file-hook - Declare file name context dependent configuration
n add-file-hook "extensions" "fhook-name"
add-file-hook defines a macro binding between a file name or file type and a set of macros. This binding enables file type dependent screen highlighting and key bindings to be performed. For a higher level introduction refer to File Hooks.
add-file-hook operates in two different modes to establish the type of file:-
Content recognition has the highest priority and is used in preference to the file extension.
add-file-hook is called multiple times to add new recognition rules. The rules are interrogated in last-in-first-out (LIFO) order, hence the extension added last has a greater precedence than those added first. This ordering allows default rules to be over-ridden.
add-file-hook must be initialized prior to the first call, using an invocation of the form:-
0 add-file-hook
with a numeric argument n of 0, and no arguments. This invocation resets the file hooks by deleting all of the installed hooks.
add-file-hook with no numerical argument n allows the extension of a file (or the base file name if there is no extension) to be used to determine which user defined setup macro is to be executed. The extensions argument is a space separated list of file endings (as opposed to true extensions) and is usually specified with the extension separator. For example, the extension ".doc" may indicate that the file is a document and therefore the indent, wrap and justify buffer modes are required. This may be performed automatically by defining a macro which adds these modes and adding a file hook to automatically execute this macro whenever a file "*.doc" is loaded.
The command arguments are defined as follows:-
extensions
fhook-name
As an example:-
define-macro fhook-doc 1 buffer-mode "indent" 1 buffer-mode "wrap" 1 buffer-mode "justify" !emacro add-file-hook ".doc" "fhook-doc"
It is quite possible that the same macro should be executed for a text file, i.e. "*.txt" this is achieved by a single add-file-hook as the space (' ') character is used as an extension separator, e.g.
add-file-hook ".doc .txt" "fhook-doc"
There are two special file hooks, which are fhook-binary and fhook-default, these are not predefined, but if the user defines them then they are executed whenever a file is loaded in binary mode (see buffer-mode(2)) or the extension does not match any of those defined.
Considering the fhook-XXX prefix, the initial 'f' character must be present as this is changed to a 'b' and an 'e' when looking for the enter (begin) buffer and exit buffer hooks. These hooks are executed whenever the user swaps to or from a buffer (including creating and deleting). So for the given example, if the tab size of 8 is required in a document (but 4 elsewhere) then this operation this is performed by defining the bhook-XXX and ehook-XXX macros, e.g.:-
define-macro bhook-doc set-variable $tabsize 8 !emacro define-macro ehook-doc set-variable $tabsize 4 !emacro
File hooks are often used to setup the desired buffer modes, hilighting, local key bindings, abbreviation file, etc.
Buffer hooks are usually used to set and restore conflicting global variables.
add-file-hook with a non-zero numerical argument n defines a macro binding between the content in a file and a set of macros. This binding enables file type dependent screen hi-lighting and key binding to be performed. For a full description of file hooks refer to File Hooks, for file extension dependent hooking refer to add-file-hook(2).
The content defined file hooks interrogate the contents of a file on loading and search for a magic string identifier embedded in the text which uniquely identifies the file type.
The recognition process performs a search of the first n (numerical argument) non-blank lines of the file, searching for the regular expression specified by the extensions argument. The sign of the numerical argument n is interpreted as follows:-
The command arguments are defined as follows:-
extensions
fhook-name
The search commences from the first non-blank line in the file, if the regular expression, defined by extensions is located then the file hook fhook-name is invoked. This is typically used to identify files which do not have file extensions i.e. UNIX shell script files. To identify a shell script file which commences with:-
#!/bin/sh
The following file hook is used:-
1 add-file-hook "#!/.*sh" "fhook-shell"
Note that ".*sh" also matches /bin/csh, /usr/local/bin/zsh etc, so care should be taken to ensure that the regular expression string is sufficiently well specified to recognize the file type.
The second class of embedded text are explicit identifiers embedded into the text. The embedded strings take the form:
-*- mode -*
-*- Mode: mode; ... -*-
-!- mode -!-
The -*- notation belongs to GNU Emacs, but MicroEmacs '99 recognizes the construct and extracts the string correctly. The -!- notation is MicroEmacs '99 specific and is provided so as not to cause conflict with GNU Emacs. MicroEmacs '99 searches for either construct on the first non-blank line of the file.
The explicit strings are defined with a negative numerical argument n, which identifies them as explicit rather than magic text strings. The string should be defined in lower case and matches a case insensitive string take from the file. e.g. to define a file hook for a make file:
#_____________________________-!-Makefile-!-________________________________ # # Make file for MicroEmacs using the Microsoft MSCV 2.0/4.0 development kit. # # Author : Jon Green # Created : 020197.1002 # Last Edited : <150297.1942> # File : makefile.w32 ....
might be defined as:
-1 add-file-hook "-!-[ \t]*makefile.*-!-" fhook-make
add-file-hook performs an automatic load of a macro file if the fhook macro is not present in memory. The file name of the command file containing the macro is automatically derived from the name component of the fhook macro name. The fhook- part of the name is stripped off and prepended with hk and suffixed with .emf. Hence, macro fhook-doc would be searched for in file hkdoc.emf within the MicroEmacs '99 directory. The command file is automatically loaded and executed.
In cases where the fhook macro is not located in an equivalent hook file, the file location of the macro may be explicitly defined for auto loading via a define-macro-file(2) invocation.
As an example, consider the C-mode file hook, used to load .c files. The loading of a C header file (.h) utilizes the same highlighting modes, but it's startup sequence is slightly different when handling new files. In this case the fhook-cmode for .c and fhook-hmode for .h files are located in the same hook file namely hkcmode.emf.
define-macro-file hkcmode fhook-hmode add-file-hook ".c .cc .cpp .def .l .y .i .ac" "fhook-cmode" add-file-hook ".h .hpp" "fhook-hmode"
In this case the define-macro-file has been used to inform MicroEmacs '99 of the location of the fhook-hmode macro thereby overriding the automatic load of a file called hkhmode.emf. The fhook-cmode macro requires no such definition as it is located in a hook file that matches the mode name, hkcmode.emf.
The standard file hook files hkXXX.emf should not be modified. The standard file hooks may be extended with local definitions by defining a file myXXX.emf, which is an extension to the hook file hkXXX.emf. This is automatically executed after hkXXX.emf. Refer to sections Language Templates and File Hooks for details.
The file extensions are specified as a space separated list of file name endings. Back-up file endings such as tilde (~) are not classed as correct file endings and are skipped by the file hook search, hence a file ending ".c~" invokes the same hook function as a ".c" file. It is therefore not necessary to add the backup and auto-save endings to the file hook definition.
The extension separator, usually dot (.), is typically added to the extensions list, they may be omitted with effect where a file always ends in the same set of characters. A notable example is "makefile" which includes no extension, as such, MicroEmacs '99 applies the same hook function to a file called Imakefile as the endings are the same.
It is sometimes useful to associate file types as binary files, so that they are immediately loaded in binary. In this case, both file extension and content recognition methods (i.e. of a magic string) are applicable. In both cases the file is bound to the well known hook fhook-binary which automatically loads the file in a binary mode.
Note, that for the content recognition process for a binary hook, the load time is doubled as the file is initially loaded in the default text mode, the binary hook function forces a second load operation in binary.
add-file-hook is summarized as follows:-
The standard set of supported file types by MicroEmacs '99, at the time of writing, is defined as:-
; reset the file hook list 0 add-file-hook ; Add file extension hooks. ; Files loaded in binary mode do not need hook as fixed add-file-hook "*help* *info* .ehf" fhook-ehf add-file-hook "*bindings* *commands* *variables*" fhook-lists add-file-hook "*buffers*" fhook-blist add-file-hook "/ *directory* *files*" fhook-dir add-file-hook "*registry*" fhook-reg add-file-hook "*icommand* *shell* *gdb* *dbx*" fhook-ipipe add-file-hook ".emf" fhook-emf add-file-hook ".doc .txt" fhook-doc add-file-hook ".1 .2 .3 .4 .5 .6 .7 .8 .9 .so .tni .sm" fhook-nroff add-file-hook ".c .h .def .l .y .i" fhook-c add-file-hook ".cc .cpp .hpp .rc" fhook-cpp add-file-hook "Makefile makefile .mak" fhook-make add-file-hook "Imakefile imakefile" fhook-imake add-file-hook ".sh .ksh .csh .login .cshrc .profile .tcshrc" fhook-shell add-file-hook ".bat .btm" fhook-dos add-file-hook ".man" fhook-man add-file-hook ".dmn" fhook-dman add-file-hook ".ini .hpj .reg .rgy" fhook-ini add-file-hook ".htm .html" fhook-html add-file-hook ".htp .hts" fhook-hts add-file-hook ".tcl" fhook-tcl add-file-hook ".rul" fhook-rul add-file-hook ".awk .nawk .gawk" fhook-awk add-file-hook ".p .pas" fhook-pascal add-file-hook ".vhdl .vhd" fhook-vhdl add-file-hook ".fvwm .fvwm2rc" fhook-fvwm add-file-hook ".java .jav" fhook-java add-file-hook ".nsr" fhook-nsr add-file-hook ".erf" fhook-erf ; Add magic hooks 1 add-file-hook "^#!/.*sh" fhook-shell ; UNIX shell files 1 add-file-hook "^#!/.*wish" fhook-tcl 1 add-file-hook "^#!/.*awk" fhook-awk 1 add-file-hook "^#VRML" fhook-vrml -4 add-file-hook "<html>" fhook-html -1 add-file-hook "-[*!]-[ \t]*c.*-[*!]-" fhook-c ; -*- C -*- -1 add-file-hook "-[*!]-[ \t]*c\\+\\+.*-[*!]-" fhook-cpp ; -*- C++ -*- -1 add-file-hook "-[*!]-[ \t]nroff.*-[*!]-" fhook-nroff ; -*- nroff -*- -1 add-file-hook "-!-[ \t]*shell.*-!-" fhook-shell ; -!- shell -!- -1 add-file-hook "-!-[ \t]*msdos.*-!-" fhook-dos ; -!- msdos -!- -1 add-file-hook "-!-[ \t]*makefile.*-!-" fhook-make ; -!- makefile -!- -1 add-file-hook "-!-[ \t]*document.*-!-" fhook-doc ; -!- document -!- -1 add-file-hook "-!-[ \t]*fvwm.*-!-" fhook-fvwm ; -!- fvwm -!- -1 add-file-hook "-!-[ \t]*erf.*-!-" fhook-erf ; -!- erf -!- -1 add-file-hook "-!-[ \t]*fold:.*-!-" fhook-fold ; -!- fold:... -!-
This section includes some low-level information which is so obscure it is not relevant to the typical user.
There is a potential loading order problem involving auto-loading of file libraries and the setting up of bhook and ehook. E.g. if the main fhook function has been defined as a define-macro-file(2), but the bhook or ehooks have not the when a buffer is created as only the fhook is define, only the fhook is set, the rest remain disabled even though the execution of the macro file will define these extra hooks.
To solve this problem simply define the bhook/ehooks as well. Note that automatically loaded hooks do not suffer from this problem as the macro file is executed before the hooks are assigned, thereby ensuring the all the hooks are defined.
(c) Copyright JASSPA 1999
Last Modified: 1999/02/27
Generated On: 1999/12/01