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RE: Is it possible for a macro to expand to nothing?
From: |
Drew Adams |
Subject: |
RE: Is it possible for a macro to expand to nothing? |
Date: |
Mon, 23 Nov 2009 08:03:06 -0800 |
> That is, not to a call to a null defun, but truly to nothing:
> i.e., the
> ensuing code (as least, when byte compiled) will be identical
> to what it
> would have been, had the macro invocation been omitted.
>
> I want something like this:
>
> (defmacro ifdef (condition &rest forms)
> "If the compile time CONDITION is non-nil, dump the FORMS to the
> calling defun. Otherwise do nothing."
> ......)
Hi Alan,
I'm not sure what you mean. But if you mean something like "insert nothing",
then you can do that by producing nil and then using ,@ inside a backquote. IOW,
instead of inserting nil, you splice it in, which means inserting nothing.
HTH.
- Is it possible for a macro to expand to nothing?, Alan Mackenzie, 2009/11/23
- RE: Is it possible for a macro to expand to nothing?,
Drew Adams <=
- Message not available
- Re: Is it possible for a macro to expand to nothing?, Alan Mackenzie, 2009/11/23
- RE: Is it possible for a macro to expand to nothing?, Drew Adams, 2009/11/23
- Re: Is it possible for a macro to expand to nothing?, Pascal J. Bourguignon, 2009/11/23
- RE: Is it possible for a macro to expand to nothing?, Drew Adams, 2009/11/23
- Message not available
- Re: Is it possible for a macro to expand to nothing?, Pascal J. Bourguignon, 2009/11/23
- Re: Is it possible for a macro to expand to nothing?, Alan Mackenzie, 2009/11/23
- RE: Is it possible for a macro to expand to nothing?, Drew Adams, 2009/11/23
- Message not available
- Re: Is it possible for a macro to expand to nothing?, Pascal J. Bourguignon, 2009/11/23
- Re: Is it possible for a macro to expand to nothing?, Alan Mackenzie, 2009/11/23
- Re: Is it possible for a macro to expand to nothing?, Pascal J. Bourguignon, 2009/11/24