Re: gen_iocsh_reg.pl

[Michael Davidsaver via Tech-talk <tech-talk@aps.anl.gov>]

This reminds me.  I added a boilerplate reduction helper
in the pvAccessCPP module.  This has now appeared in several
epics 7.0 releases.

Usage looks like:

> #include <pv/iocshelper.h>
> void startPVAServer(const char *names) ...
> ...
> void someRegistar() {
>   epics::iocshRegister<const char*, &startPVAServer>("startPVAServer", "provider names");

Ugly, still somewhat repetitive ('const char*' appears twice),
and currently only for functions with between 0 and 3 arguments
due to the limitations of c++98.

https://github.com/epics-base/pvAccessCPP/blob/master/src/ioc/pv/iocshelper.h


On 4/26/19 8:44 AM, Benjamin Franksen via Tech-talk wrote:
> I recently wrote this little perl script (attached) to automate the
> writing of iocsh registration code using a trivial but (I think)
> complete declarative specification "language" that is easy to compose on
> the command line or in a Makefile. I am posting the code and an example
> of what it does in the hope that it may turn out to be useful for others.
> 
> Here is the help output (slightly re-formatted for this email):
> 
> """
>> gen_iocsh_reg.pl -h
> Usage: gen_iocsh_reg.pl [REG=<registrar>] <command>=[<args>] ...
> where
>   <registrar> is the name of a C function to register the commands (if
>     not specified you'll have to call iocshRegister yourself for each
>     command)
>   <command> is the name of a command (in C as well as in the shell)
>   <args> is a comma separated list of argument descriptions <arg>
>   <arg> describes an argument to the underlying C command and is either
>     * a constant literal value (for instance 0 or "a string"), or
>     * an iocsh argument description of the form <name>:<type> (for
>       instance card_number:Int) where <type> is one of {Int, Double,
>       String}.
> Only arguments of the <name>:<type> sort are exposed as arguments to the
> command in the shell.
> """
> 
> Here is a real-world example use case,. This is from a Makefile in one
> of our projects:
> 
> """
> iocshExtra.c:
>         $(PERL) $(BII_SCRIPTS_BIN)/gen_iocsh_reg.pl REG=registerIocshExtra\
>          asDump=0,0,verbosity:Int \
>          bootShow= bootChange= \
>          gevShow= gevDelete=name:String
> gevUpdate=name:String,value:String > $@
> """
> 
> From this it generates the following boilerplate code:
> 
> """
> /*
>  * IOC shell command registration
>  */
> 
> #include "epicsExport.h"
> #include "iocsh.h"
> 
> static const iocshArg asDumpArg0 = { "verbosity", iocshArgInt };
> static const iocshArg *const asDumpArgs[] = {
>     &asDumpArg0
> };
> static const iocshFuncDef asDumpDef = {"asDump", 1, asDumpArgs};
> static void asDumpWrapper(const iocshArgBuf *args) {
>     asDump(0, 0, args[0].ival);
> }
> 
> static const iocshArg *const bootChangeArgs[] = {};
> static const iocshFuncDef bootChangeDef = {"bootChange", 0, bootChangeArgs};
> static void bootChangeWrapper(const iocshArgBuf *args) {
>     bootChange();
> }
> 
> static const iocshArg *const bootShowArgs[] = {};
> static const iocshFuncDef bootShowDef = {"bootShow", 0, bootShowArgs};
> static void bootShowWrapper(const iocshArgBuf *args) {
>     bootShow();
> }
> 
> static const iocshArg gevDeleteArg0 = { "name", iocshArgString };
> static const iocshArg *const gevDeleteArgs[] = {
>     &gevDeleteArg0
> };
> static const iocshFuncDef gevDeleteDef = {"gevDelete", 1, gevDeleteArgs};
> static void gevDeleteWrapper(const iocshArgBuf *args) {
>     gevDelete(args[0].sval);
> }
> 
> static const iocshArg *const gevShowArgs[] = {};
> static const iocshFuncDef gevShowDef = {"gevShow", 0, gevShowArgs};
> static void gevShowWrapper(const iocshArgBuf *args) {
>     gevShow();
> }
> 
> static const iocshArg gevUpdateArg0 = { "name", iocshArgString };
> static const iocshArg gevUpdateArg1 = { "value", iocshArgString };
> static const iocshArg *const gevUpdateArgs[] = {
>     &gevUpdateArg0,
>     &gevUpdateArg1
> };
> static const iocshFuncDef gevUpdateDef = {"gevUpdate", 2, gevUpdateArgs};
> static void gevUpdateWrapper(const iocshArgBuf *args) {
>     gevUpdate(args[0].sval, args[1].sval);
> }
> 
> static void registerIocshExtra(void) {
>     static int firstTime = 1;
>     if (firstTime) {
>         firstTime = 0;
>         iocshRegister(&asDumpDef, asDumpWrapper);
>         iocshRegister(&bootChangeDef, bootChangeWrapper);
>         iocshRegister(&bootShowDef, bootShowWrapper);
>         iocshRegister(&gevDeleteDef, gevDeleteWrapper);
>         iocshRegister(&gevShowDef, gevShowWrapper);
>         iocshRegister(&gevUpdateDef, gevUpdateWrapper);
>     }
> }
> epicsExportRegistrar(registerIocshExtra);
> """
> 
> Cheers
> Ben
>

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