Use perl instead of sed

[FreddieAkeroyd]

Windows does not have sed so change to use perl that is already needed for building EPICS

See #62

[FreddieAkeroyd]

Have converted to draft as though it works on windows it doesn't on linux. The problem is that ' does not work on windows but using " means the perl variables $ get interpreted by the linux shell. Tried adding \ which makes it work on linux but then stops working on windows. Could get round this by putting the perl code in a separate file rather than using -e but maybe there is some cleverer quoting that can be done

[simon-ess]

It might be possible to do something like

ifeq ($(strip $(OS_CLASS)),WIN32)
 QUOTE="
else
 QUOTE='
endif


$(COMMON_DIR)/siteEnvVars.substitutions: $(EPICS_BASE)/configure/CONFIG_SITE_ENV
	@echo Expanding siteEnvVars.substitutions from CONFIG_SITE_ENV....
	@echo file iocEnvVar.template> $@
	@echo {>> $@
	@echo pattern>> $@
	@echo { ENVNAME, ENVVAR, ENVTYPE }>> $@
	@perl -n -e $(QUOTE)$$m = s/^EPICS_([A-Z_]*).*/{$${1}, EPICS_$${1}, epics}/; print $$_ if $$m;$(QUOTE) < $< >> $@
	@echo }>> $@

though I am not sure this is much better... 😄

[simon-ess]

See e.g. https://stackoverflow.com/questions/13631551/make-echo-includes-quotes-in-generated-file

[FreddieAkeroyd]

Well it makes it clear what we are trying to do at least, I am happy to go with that if you are - thanks

[FreddieAkeroyd]

Unless you think putting the s/ command into a separate file for perl to execute from Make is cleaner

[anjohnson]

Surely it would be simpler to use a stand-alone Perl script to do the whole job of generating the siteEnvVars.substitutions file? There'd be no need to mess around with the $(QUOTE) variable, and the Perl code would also be easier to read and modify. That might even fix the Base-3.14 build failure, but I haven't looked at that properly to be sure.

[simon-ess]

Oh no more perl scripts

😄

Anyhow, I think you are correct in this case that a standalone script is easier; this is a pretty simple parsing, but the solution is better.

[simon-ess]

Maybe add a shebang, usage, and copyright notice?

[simon-ess]

Probably better to use $(PERL) here instead of directly calling perl

This I leave up to you, but I think I would prefer a perl script that does not read from stdin but takes a file as an argument; looking at most of the perl scripts in use in various EPICS modules that seems to be more the more consistent standard.

[anjohnson]

+1 on using $(PERL).

Most Base build rules that run generator scripts start with @$(RM) $@ to explicitly delete the target file first, so any errors which result in the script not actually regenerating the output file will trigger an error from GNUmake instead of it just continuing without recreating the file. I guess that's an enhancement request since the original rule didn't do that, but I recommend adding it anyway.

Switching from stdin to a filename argument might not need any changes to your Perl code at all, since using while (<>) { ... } in Perl inline code automatically opens and parses the files listed in @ARGV anyway (improve on that, Python!).

[anjohnson]

Using a here-doc could reduce the number of quotes and escaped newlines, and I recommend always quoting the argument to file (again, not in the original). My personal preference for formatting substitution files would have fewer newlines:

print << __END__;
file "iocEnvVar.template" {
  pattern { ENVNAME, ENVVAR, ENVTYPE }
__END__