FvwmCpp - the FVWM Cpp pre-processor

Module FvwmCpp [options] filename

The FvwmCpp module can only be invoked by fvwm. Command line invocation of the FvwmCpp module will not work.

When fvwm executes the FvwmCpp module, FvwmCpp invokes the cpp pre-processor on the file specified in its invocation, then FvwmCpp causes fvwm to execute the commands in the resulting file.

FvwmCpp can be invoked as a module using an fvwm command, from the .fvwm2rc file, a menu, mousebinding, or any of the many other ways fvwm commands can be issued.

If the user wants his entire .fvwm2rc file pre-processed with FvwmCpp, then fvwm should be invoked as:

fvwm -cmd "Module FvwmCpp .fvwm2rc"

Note that the argument to the option "-cmd" should be enclosed in quotes, and no other quoting should be used.

When FvwmCpp runs as a module, it runs asynchronously from fvwm. If FvwmCpp is invoked from the .fvwm2rc, the commands generated by FvwmCpp may or may not be executed by the time fvwm processes the next command in the .fvwm2rc. Invoke FvwmCpp this way for synchronous execution:

ModuleSynchronous FvwmCpp -lock filename

Some options can be specified following the modulename:

-cppopt option

Lets you pass an option to the cpp program. Not really needed as any unknown options will be passed on automatically.

-cppprog name

Instead of invoking "/usr/lib/cpp", fvwm will invoke name.

-outfile filename

Instead of creating a random unique name for the temporary file for the preprocessed rc file, this option will let you specify the name of the temporary file it will create. Please note that FvwmCpp will attempt to remove this file before writing to it, so don't point it at anything important even if it has read-only protection.

-debug

Causes the temporary file create by Cpp to be retained. This file is usually called "/tmp/fvwmrcXXXXXX"

-lock

If you want to use this option you need to start FvwmCpp with ModuleSynchronous. This option causes fvwm to wait that the pre-process finish and that FvwmCpp asks fvwm to Read the pre-processed file before continuing. This may be useful at startup if you use a session manager as Gnome. Also, this is useful if you want to process and run a Form in a fvwm function.

-noread

Causes the pre-processed file to be not read by fvwm. Useful to pre-process a FvwmScript script with FvwmCpp.

FvwmCpp defines some values for use in the pre-processor file:

TWM_TYPE

Always set to "fvwm".

SERVERHOST

The name of the machine running the X Server.

CLIENTHOST

The name of the machine running fvwm.

HOSTNAME

The host name of the machine running fvwm. Generally the same as CLIENTHOST.

OSTYPE

The operating system for CLIENTHOST.

USER

The name of the person running fvwm.

HOME

The home directory of the person running fvwm.

VERSION

The X11 version.

REVISION

The X11 revision number.

VENDOR

The X server vendor.

RELEASE

The X server release number.

SCREEN

The screen number.

WIDTH

The screen width in pixels.

HEIGHT

The screen height in pixels.

X_RESOLUTION

Some distance/pixel measurement for the horizontal direction, I think.

Y_RESOLUTION

Some distance/pixel measurement for the vertical direction, I think.

PLANES

Number of color planes for the X server display

BITS_PER_RGB

Number of bits in each rgb triplet.

CLASS

The X11 default visual class, e.g. PseudoColor.

COLOR

Yes or No, Yes if the default visual class is neither StaticGrey or GreyScale.

FVWM_CLASS

The visual class that fvwm is using, e.g. TrueColor.

FVWM_COLOR

Yes or No, Yes if the FVWM_CLASS is neither StaticGrey or GreyScale.

FVWM_VERSION

The fvwm version number, ie 2.0

OPTIONS

Some combination of SHAPE, XPM, NO_SAVEUNDERS, and Cpp, as defined in configure.h at compile time.

FVWM_MODULEDIR

The directory where fvwm looks for .fvwm2rc and modules by default, as determined at compile time.

FVWM_USERDIR

The value of $FVWM_USERDIR.

SESSION_MANAGER

The value of $SESSION_MANAGER. Undefined if this variable is not set.

#define TWM_TYPE fvwm #define SERVERHOST spx20 #define CLIENTHOST grumpy #define HOSTNAME grumpy #define OSTYPE SunOS #define USER nation #define HOME /local/homes/dsp/nation #define VERSION 11 #define REVISION 0 #define VENDOR HDS human designed systems, inc. (2.1.2-D) #define RELEASE 4 #define SCREEN 0 #define WIDTH 1280 #define HEIGHT 1024 #define X_RESOLUTION 3938 #define Y_RESOLUTION 3938 #define PLANES 8 #define BITS_PER_RGB 8 #define CLASS PseudoColor #define COLOR Yes #define FVWM_VERSION 2.0 pl 1 #define OPTIONS SHAPE XPM Cpp #define FVWM_MODULEDIR /local/homes/dsp/nation/modules #define FVWM_USERDIR /local/homes/dsp/nation/.fvwm #define SESSION_MANAGER local/grumpy:/tmp/.ICE-unix/440,tcp/spx20:1025

Module configurations do not become active until fvwm has restarted if you use FvwmCpp on startup. FvwmCpp creates a temporary file and passes this to fvwm, so you would have to edit this file too. There are some problems with comments in your .fvwm2rc file. The comment sign # is misinterpreted by the preprocessor. This has usually no impact on functionality but generates annoying warning messages. The sequence /* is interpreted as the start of a C comment what is probably not what you want in a filename. You might want to try /?* (for filenames only) or /\* or "/*" instead. Depending on your preprocessor you may have the same problem with "//". Macros are not replaced within single (') or double quotes ( back quotes (`) to circumvent this. Fvwm accepts back quotes for quoting and at least FvwmButtons does too. The preprocessor may place a space after a macro substitution, so with #define MYCOMMAND ls "Exec "MYCOMMAND" -l" you might get "Exec "ls " -l" (two words) and not "Exec "ls" -l" (one word).

If you use gcc you can use this invocation to turn off '//' comments:

FvwmCpp -Cppprog '/your/path/to/gcc -C -E -' <filename>

FvwmCpp is the result of a random bit mutation on a hard disk, presumably a result of a cosmic-ray or some such thing.