Hi –
I’ve been hunting through old RCRs, and came across my favorite
rejected one:
http://oldrcrs.rubypal.com/rejected.html#rcr120
Still trying to find that map(:sym) one…
David
–
The Ruby training with D. Black, G. Brown, J.McAnally
Compleat Jan 22-23, 2010, Tampa, FL
Rubyist http://www.thecompleatrubyist.com
David A. Black/Ruby Power and Light, LLC (http://www.rubypal.com)
On Sun, 8 Nov 2009, David A. Black wrote:
Hi –
I’ve been hunting through old RCRs, and came across my favorite
rejected one:
And its near-relation:
http://oldrcrs.rubypal.com/rejected.html#rcr94
Found it! See map(:sym) thread…
David
–
The Ruby training with D. Black, G. Brown, J.McAnally
Compleat Jan 22-23, 2010, Tampa, FL
Rubyist http://www.thecompleatrubyist.com
David A. Black/Ruby Power and Light, LLC (http://www.rubypal.com)
On 8 Nov 2009, at 15:41, David A. Black wrote:
I always wanted http://oldrcrs.rubypal.com/rejected.html#rcr2 - but
then again I also want goal direction to scratch my (un)icon itches
Ellie
raise ArgumentError unless @reality.responds_to? :reason
On Sunday 08 November 2009 08:32:53 am David A. Black wrote:
Hi –
I’ve been hunting through old RCRs, and came across my favorite
rejected one:
Actually, it looks like rcr124 was eventually accepted as BasicObject,
right?
I can see why rcr147 was rejected, but it’s not entirely without
precedent –
see .profile for sh and bash.
And rcr169, I actually like. What if the exception was raised deep in
another
method, but it’s something you can handle? Also not without precedent,
as Lisp
has these.
Not to re-open old discussions, I just thought it was interesting –
especially #124, which was rejected, and is now implemented. Seems the
rejection isn’t final.
On Mon, 9 Nov 2009, David M. wrote:
On Sunday 08 November 2009 08:32:53 am David A. Black wrote:
Hi –
I’ve been hunting through old RCRs, and came across my favorite
rejected one:Actually, it looks like rcr124 was eventually accepted as BasicObject, right?
It’s a little different: the reason for rejection was:
See technique used in delegate.rb for such purpose.
as opposed to the reason for rejection of 120, which was:
No, it should not.
Also, though I can’t remember the details, I seem to remember that
Matz actually suggested that someone submit such an RCR so that he
could comment definitively on the matter and spare everyone from
revisiting the question over and over again.
I can see why rcr147 was rejected, but it’s not entirely without precedent –
see .profile for sh and bash.And rcr169, I actually like. What if the exception was raised deep in another
method, but it’s something you can handle? Also not without precedent, as Lisp
has these.
True, but the business of precedents from other languages sort of
cancels itself out, since it encompasses literally tens or hundreds of
thousands of features, large and small. Of course lots of Ruby
features are adopted or adapted from other languages; but I don’t
think the presence of a feature or practice in another language,
per se, militates in favor of its inclusion in Ruby.
Not to re-open old discussions, I just thought it was interesting –
especially #124, which was rejected, and is now implemented. Seems the
rejection isn’t final.
I think the BasicObject concept (unlike the putting-class-names-in-
method-signatures concept) was bubbling under the surface for a long
time, and appeared in various incarnations, including the delegate.rb
technique that Matz referred to as well as Jim W.'s BlankSlate
class, before being adopted into the family tree. It wasn’t a case of
something fundamentally out of character for the language. Not all RCR
rejection is created equal (And part of that, too, is of course
that Matz can change his mind over time.)
David
–
The Ruby training with D. Black, G. Brown, J.McAnally
Compleat Jan 22-23, 2010, Tampa, FL
Rubyist http://www.thecompleatrubyist.com
David A. Black/Ruby Power and Light, LLC (http://www.rubypal.com)
On 9 Nov 2009, at 14:27, Brian C. wrote:
Eleanor McHugh wrote:
I always wanted http://oldrcrs.rubypal.com/rejected.html#rcr2 - but
then again I also want goal direction to scratch my (un)icon
itchesIs that more or less what Fiber is in 1.9 ?
It could be viewed that way, however a closer analogue to icon’s usage
would be for all blocks to be generators without recourse to an OO
abstraction. However that’s an ancient argument and probably not worth
reopening.
Thinking about it though I could probably build an icon-style goal-
directed evaluator using Fiber and wrap it in a DSL that would make
coding with it feel very very similar. I’ll have to take a look at
that when I have some free time to play with.
Ellie
raise ArgumentError unless @reality.responds_to? :reason
Eleanor McHugh wrote:
I always wanted http://oldrcrs.rubypal.com/rejected.html#rcr2 - but
then again I also want goal direction to scratch my (un)icon itches
Is that more or less what Fiber is in 1.9 ?
On Sunday 08 November 2009 03:44:15 pm David A. Black wrote:
On Mon, 9 Nov 2009, David M. wrote:
I can see why rcr147 was rejected, but it’s not entirely without
precedent – see .profile for sh and bash.And rcr169, I actually like. What if the exception was raised deep in
another method, but it’s something you can handle? Also not without
precedent, as Lisp has these.True, but the business of precedents from other languages sort of
cancels itself out, since it encompasses literally tens or hundreds of
thousands of features, large and small.
My point wasn’t that it had ever been done, but that it had been done
well,
and had been found to be useful. For example, while I could simply
include a
list of environment variables somewhere, or tweak the bash commandline
from
/etc/passwd, it’s much more convenient to be able to use actual shell
logic in
/etc/profile and .profile to set those variables.
Yes, it can screw things up, if misused. I don’t think that’s a reason
not
to do it.
Similarly, Lisp restarts, when I read Practical Common Lisp, seemed to be
really useful and something I’d miss in Ruby. In the book’s example,
he’s got
a log parser, with two restarts: parse-log-entry and skip-log-entry.
That is,
you could do something roughly equivalent to this:
begin
logfile = LogParser.parse(‘/some/file’)
rescue LogParser::MalformedEntry
entry = $!.text
if entry =~ /some_regex/
restart :reparse, entry.gsub(/some/, ‘substitution’)
else
restart :skip
end
end
I’m not attached to that syntax (actually, the ‘restart’ in particular
looks
cumbersome), but the point is that this is much more flexible than
something
like this:
LogParser.parse(‘/some/file’, :skip_malformed => true, :fix_bad_entry =>
proc{|
x| x.gsub(/some/, ‘substitution’)})
First, that’s not quite equivalent (and it’s a little ugly). Second,
it’s much
nicer to be able to actually separate the error handling logic.
And finally, one of the main points of exceptions – to me, at least –
is that
you don’t need to have specific error-handling logic within each method
that
might throw an error. (This is something Java gets horribly wrong, by
the way
– having to manually specify “throws” almost defeats the purpose.) It
means
the error will be handled, even if it’s somewhere much farther up the
call
stack, even if “handling” means aborting the program rather than letting
an
error be silently ignored.
So, it makes sense that if the error actually can be corrected up the
call
stack, it should be. For example:
def foo
…
LogParser.parse …
…
end
begin
foo
rescue LogParser::MalformedEntry
…
end
The closest thing we currently have is “retry”, which re-runs the entire
block. Obviously, this isn’t a good idea if we’re halfway through a
multi-
gigabyte log, and it doesn’t help us actually correct the error.
Am I missing something obvious? Maybe a design pattern which avoids
this, or
maybe a way to implement the equivalent without changing Ruby itself?
I think the BasicObject concept (unlike the putting-class-names-in-
method-signatures concept) was bubbling under the surface for a long
time… It wasn’t a case of
something fundamentally out of character for the language. Not all RCR
rejection is created equal
that Matz can change his mind over time.)
That was the impression I got there. I was pointing it out partly just
to make
sure I wasn’t crazy, and that this was indeed a rejected BasicObject
idea.
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