On Thursday, 14 November 2013 at 21:12:11 UTC, Walter Bright
wrote:
On 11/14/2013 11:40 AM, deadalnix wrote:
This is not proposing to configure syntax.
Right, it is about inserting arbitrarily different meaning into
existing syntax.
For example, I have a friend from the middle east who worked at
Microsoft. His english was excellent. But sometimes he'd get
tripped up - for example, he'd take his idea to his boss, who'd
discuss it, and then say:
"fine"
He took that to mean "my boss approves of my great idea!"
Unfortunately, "fine" has undergone a meaning reversal
colloquially, and actually means "your idea sux". This wound up
getting him into trouble. There were a few other phrases like
this with unintentionally hilarious misunderstandings.
(Also, a popular way of encrypting communications is to have
private meanings for phrases like "my cat ate my homework"
meaning "initiate Operation X".)
Now, let's take the AST macros, and pass it "4+3". Apparently
is a feature that the macro can transform this to produce
"hello" as the result. The result is that although the language
looks the same, there is no "anchor" a person can rely on to
indicate the meaning. The meaning of "fine" is reversed, so to
speak.
The riposte is, of course, every feature can be abused and good
programmers won't do that. Unfortunately, it's IN THE VERY
NATURE of macros to be abusive, and even the very best
programmers can and will take it to the limit. They will see
and decry the abuse in everyone else's code but their own,
which they will justify. As I said, I see this over and over
again.
On the other hand, with string mixins, it is immediately
obvious that one is dealing with different syntax, and so
expect something different to happen.
You have a point with the example, but just as with templates (
the distinctive binary ! operator), making macros not to look
first class language elements when called does great job with
readability. #-s or ×-s are just good for this, even if it look
very foreign.
#loop ( ) {
-- code --
}
Maybe for macros that return macros it would be ugly:
#(#macro1(params1))(params2);
But just as in C where the -> operator automatically dereferences
pointers, it could be solved.
# macro1(params1) =#= (params2);
(Just for fun)
