Re: Escaping a ',' in autoconf

[Ralf Wildenhues]

* Ralf Wildenhues wrote on Wed, Oct 26, 2005 at 08:53:26AM CEST:
> * Kristis Makris wrote on Wed, Oct 26, 2005 at 03:07:47AM CEST:
> > 
> > I'm having a hard time escaping a comma (',') in autoconf. I'm trying to
> > set to a variable the regular expression: [,\s#]. I can set almost
> > everything, except the comma:
> > 
> > DEVEL_CONFIG_TEMPLATE_BUGID_SPLIT_REGEX="@<:@address@hidden:@@:>@"
> > 
> > Can anyone recommend how this is done ?
> 
> Outside of any macro definitions or calls (the former is really a
> special case of the latter), a comma should not hurt at all.
> Inside, you should ensure to have quoted enough.  The general rule is:
> One level of quotation per level of nesting.

And I forgot the other half of the mail, sorry:
Literals are to be quoted twice.  So then you end up writing the literal
  [,\s#]
as
  [[,\s#]]
or, in other words:
 DEVEL_CONFIG_TEMPLATE_BUGID_SPLIT_REGEX="[[,\s#]]"

Some people prefer to put the outer pair of brackets (which are really
just the second m4 quotation further outside, at least for more
complicated expressions:

  [compicated_regex='[^a-z]*[a-z]']
instead of
  compicated_regex='[[^a-z]]*[[a-z]]'

but since m4 really doesn't care much about shell syntax, it does not
matter so much, but is up to personal preference.

Cheers,
Ralf