behaviour change of String#gsub(pattern) {|m| ... } for ruby 1.9/ruby2?

[David Garamond]

String#gsub(pattern) {|m| ... }

It really would be nice to get match data in 'm', but this would surely
break _a lot_ of scripts. How about String#regsub, #regsub!, #resub,
#resub! ? What do others think?

--
dave

[Yukihiro Matsumoto]

Hi,

In message "behaviour change of String#gsub(pattern) {|m| ... } for ruby 1.9/ruby2?"
on 03/11/20, David Garamond <lists@zara.6.isreserved.com> writes:

|String#gsub(pattern) {|m| ... }
|
|It really would be nice to get match data in 'm', but this would surely
|break _a lot_ of scripts. How about String#regsub, #regsub!, #resub,
|#resub! ? What do others think?

Sounds nice. The only reason for the current behavior is that sub
predates MatchData. But we have to define migration path.

matz.

[Austin Ziegler]

On Thu, 20 Nov 2003 20:57:58 +0900, Yukihiro Matsumoto wrote:

> In message "behaviour change of String#gsub(pattern) {|m| ... }
>| String#gsub(pattern) {|m| ... }
>|
>| It really would be nice to get match data in 'm', but this would
>| surely break _a lot_ of scripts. How about String#regsub,
>| #regsub!, #resub, #resub! ? What do others think?
> Sounds nice. The only reason for the current behavior is that sub
> predates MatchData. But we have to define migration path.

Is there an easy way for String#gsub (et al.) to check the arity of
the provided block?

String#gsub(pattern) { |m, md| ... }
yields match string and matchdata

String#gsub(pattern) { |m| ... }
yields match string only

That would break the least amount of code.

-austin
--
austin ziegler * [email]austin@halostatue.ca[/email] * Toronto, ON, Canada
software designer * pragmatic programmer * 2003.11.20
* 10.18.43

[ts]

>>>>> "A" == Austin Ziegler <austin@halostatue.ca> writes:

A> Is there an easy way for String#gsub (et al.) to check the arity of
A> the provided block?

svg% cat b.rb
#!/usr/bin/ruby
def a(&block)
p block.arity
end

a {|x| }
a {|x, y| }
svg%

svg% b.rb
1
2
svg%


Guy Decoux

[Austin Ziegler]

On Fri, 21 Nov 2003 00:31:05 +0900, ts wrote:

>>>>>> "A" == Austin Ziegler <austin@halostatue.ca> writes:

> A> Is there an easy way for String#gsub (et al.) to check the arity of A>
> the provided block?

I had actually done what you did, Guy, but I don't know the C side of Ruby,
so I don't know how easy it is.

I think that this is probably a good stab at a solution, though.

-austin
--
austin ziegler * [email]austin@halostatue.ca[/email] * Toronto, ON, Canada
software designer * pragmatic programmer * 2003.11.20
* 11.31.12

[Florian Gross]

Yukihiro Matsumoto wrote:

> Hi,

Moin!

> |String#gsub(pattern) {|m| ... }
> |
> |It really would be nice to get match data in 'm', but this would surely
> |break _a lot_ of scripts. How about String#regsub, #regsub!, #resub,
> |#resub! ? What do others think?
>
> Sounds nice. The only reason for the current behavior is that sub
> predates MatchData. But we have to define migration path.

I like this, because matz told me I shouldn't be using $1 in the
gsub-block and there's no way to not do so right now. :)

Add a MatchData#to_str and it should work for most cases. We could give
a warning for cases where scripts would still be broken by this chance.

Regards,
Florian Gross

[Sabby and Tabby]

Austin Ziegler <austin@halostatue.ca> wrote:

> String#gsub(pattern) { |m, md| ... }
> yields match string and matchdata
>
> String#gsub(pattern) { |m| ... }
> yields match string only
>
> That would break the least amount of code.

Lightly tested, seems to work:

class String
alias _sub sub
alias _sub! sub!

def sub(*a, &b)
b ? _sub(*a) {|s| b.arity == 2 ? b[s, $~] : b[s]} : _sub(*a)
end

def sub!(*a, &b)
s = sub(*a, &b)
s == self ? nil : replace(s)
end
end

Not portable, fragile, sometimes works:

module Kernel
alias _sub sub
alias _sub! sub!

def sub(*a, &b)
$a, $b, $c = a, b, ""

set_trace_func(proc {|*x|
if x[0] == 'return'
eval("$c.replace($_.sub(*$a, &$b))", x[4])
set_trace_func(nil)
end
})

$c
end

def sub!(*a, &b)
$a, $b = a, b
r, w = IO.pipe

fork or return set_trace_func(proc {|*x|
w.puts(eval("$_.sub!(*$a, &$b).inspect", x[4]))
exit!
})

Process.wait
$c = eval(r.readline) or return

set_trace_func(proc {|*x|
if x[0] == 'return'
eval("$_.replace($c)", x[4])
set_trace_func(nil)
end
})

$c
end
end