Note that on 1.9 you have to use each_line since each (and enumerable)
have been removed from the String class.
JD
From: [email protected]
[mailto:[email protected]] On Behalf Of Dave Remy
Sent: Monday, June 30, 2008 1:06 PM
To: [email protected]
Subject: Re: [Ironruby-core] MutableString.each
After trying out various use cases string.each (synonym for .each_line)
is very weird. Here are some cases …
This one does not throw exception
s = “aaa”
s.each { s[0] = “b”}
=> “baa”
This one does (it has a newline) (and matches the rubyspec test case)
s = “aaa\naaa”
s.each { s[0] = “b”}
=> Runtime Error: string modified
Ok, if that is not weird enough (but maybe not completely whacked if
you consider each_line won’t really iterate until there is a newline)
s = “aaa\naaa”
modify s before iterating
s[0] = “a”
s.each { s[0] = “b”}
=> “baa\naaa”
This looks like MRI is relying on copy on write semantics to determine
whether a string was modified? Jim, says this is not the behavior for
1.9.
This seems like a good candidate for IR diverging on …
rem
From: [email protected]
[mailto:[email protected]] On Behalf Of Dave Remy
Sent: Monday, June 30, 2008 9:47 AM
To: [email protected]
Subject: Re: [Ironruby-core] MutableString.each
Translation: I need to check to assure that mri actually uses freeze to
make the string immutable while iterating. I should be able to test the
string for frozen. I just ran a test script, and nope, the string
being iterated is not frozen:
s = “aaa”
s.each { puts s.frozen? } => false
So I need to implement some other mechanism for making the iterated
string immutable during the iteration rather than freezing it. I
wonder whether other types of mutable objects that iterate have this
same behavior … I’ll do some more research.
From: [email protected]
[mailto:[email protected]] On Behalf Of John L.
(IRONRUBY)
Sent: Monday, June 30, 2008 7:23 AM
To: [email protected]
Subject: Re: [Ironruby-core] MutableString.each
You should catch and rethrow the correct exception if you want to use
the frozen detection stuff. But you should check to see if it’s actually
frozen while iterating - ie is this an observable side-effect of using
each?
Thanks,
-John
From: [email protected]
[mailto:[email protected]] On Behalf Of Curt
Hagenlocher
Sent: Sunday, June 29, 2008 4:16 PM
To: [email protected]
Subject: Re: [Ironruby-core] MutableString.each
RuntimeException is defined in
IronRuby.Libraries\Builtins\Exceptions.cs.
Is MRI really that inconsistent about which type of error is thrown when
you try to modify a frozen object? (Not that this would surprise me :(.)
If so, it might be cleaner if the call to FreezeObject could record or
otherwise influence the type of exception that we expect to throw.
From: [email protected]
[mailto:[email protected]] On Behalf Of Dave Remy
Sent: Sunday, June 29, 2008 3:58 PM
To: [email protected]
Subject: [Ironruby-core] MutableString.each
I am working on one of the specs for string.each which is failing.
This is the spec that is failing.
it “raises a RuntimeError if the string is modified while substituting”
do
str = “hello\nworld”
should_raise(RuntimeError) { str.send(cmd) { str[0] = ‘x’ } }
end
The idea is that the string that is being iterated over shouldn’t be
changed during the iteration. It is easy enough to freeze the string in
the first line of MutableString.EachLine using:
RubyUtils.GetExecutionContext(context).FreezeObject(self); Which
appropriately throws an error when the string gets modified, however
this approach throws a “TypeError” and the spec wants a “RuntimeError”
(message: String#each raises a RuntimeError if the string is modified
while substituting FAILED, Expected RuntimeError, got TypeError (can’t
modify frozen object)). I considered wrapping the code in EachLine
that invokes the each block with a try catch and then rethrowing a
caught type error exception to a runtime exception however I don’t see a
runtime exception type in RubyExceptions. Any suggestions on how best
to approach this?
Thx!
rem