[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Paul Pham. Bump... Are we any closer to a resolution on this? Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-99300 * Author: Pieter van de Bruggen * Status: Accepted * Priority: Normal * Assignee: Henrik Lindberg * Category: * Target version: * Affected Puppet version: * Keywords: backlog * Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To unsubscribe from this group and stop receiving emails from it, send an email to puppet-bugs+unsubscr...@googlegroups.com. To post to this group, send email to puppet-bugs@googlegroups.com. Visit this group at http://groups.google.com/group/puppet-bugs. For more options, visit https://groups.google.com/groups/opt_out.
[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Henrik Lindberg. This is on the agenda for Puppet 4 - it is a major semver breaking change. It may be available earlier in experimental feature form but is not going to make it in time for Puppet 3.4. Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-99302 * Author: Pieter van de Bruggen * Status: Accepted * Priority: Normal * Assignee: Henrik Lindberg * Category: * Target version: * Affected Puppet version: * Keywords: backlog * Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To unsubscribe from this group and stop receiving emails from it, send an email to puppet-bugs+unsubscr...@googlegroups.com. To post to this group, send email to puppet-bugs@googlegroups.com. Visit this group at http://groups.google.com/group/puppet-bugs. For more options, visit https://groups.google.com/groups/opt_out.
[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Reid Vandewiele.
With regards to the potential addition of a `nothing` kind of keyword, after
thinking about this for awhile I realized that I already use a largely
functional equivalent for passing around nothing in the Puppet DSL. I use an
empty array, `[ ]`. Here's a contrived example:
pre
class amanda (
$server_package = 'amanda-server',
$client_package = 'amanda-client'
) {
package { $server_package:
ensure = installed,
before = Package[$client_package],
}
package { $client_package:
ensure = installed,
}
}
case $::osfamily {
'Debian': {
# In my Debian environment, I use a Zmanda provide the amanda service
$server = 'zmanda-backup'
# zmanda-backup provides client AND server, so client should be nothing
$client = [ ]
default: {
$server = undef
$client = undef
}
}
class { 'amanda':
server_package = $server,
client_package = $client,
}
/pre
Is this the kind of usage you envision a separate nothing keyword being able
to provide? If it is, would adding a nothing keyword that simply evaluated to
an empty array provide that functionality, or is there more complexity that
needs to be carried?
Bug #15329: Puppet lacks a proper undefined value
https://projects.puppetlabs.com/issues/15329#change-78423
Author: Pieter van de Bruggen
Status: Accepted
Priority: Normal
Assignee: Henrik Lindberg
Category:
Target version:
Affected Puppet version:
Keywords: backlog
Branch:
$y = undef
notice($y == ) # true
notice($x == $y) # true
notice($x == ) # true
Recent changes in the Puppet DSL made equality commutative (good!), but in
doing so broke work-arounds for actually testing for the difference between an
undefined and empty value. The most logical fix would be to equate Puppet's
`undef` with Ruby's `nil`.
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[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Reid Vandewiele. Thanks for clarifying. Everything is starting to make more sense now. :-) I understand the use case for `undef` when used as I described. When using the DSL I've actually never thought to try and use undef to override a defined resource default by passing in `undef` as a nothing value, since in my mind undef very clearly means its mnemonic, which is to undefine a setting, thus reverting to the default. Can you indicate an example use case for wanting to pass in an explicit nothing parameter in the DSL in order to override a default, and describe the benefit (or draw/motivation) for doing so along with a pseudo-DSL sample (e.g. using a hypothetical nothing keyword)? I think a concrete example would further clarify a lot of the discussion in this thread. Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-78355 Author: Pieter van de Bruggen Status: Accepted Priority: Normal Assignee: Henrik Lindberg Category: Target version: Affected Puppet version: Keywords: backlog Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To post to this group, send email to puppet-bugs@googlegroups.com. To unsubscribe from this group, send email to puppet-bugs+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-bugs?hl=en.
[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by eric sorenson. Assignee changed from Pieter van de Bruggen to Henrik Lindberg Priority changed from High to Normal Keywords set to backlog Flagging this top-line ticket for inclusion in the project backlog. Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-74407 Author: Pieter van de Bruggen Status: Accepted Priority: Normal Assignee: Henrik Lindberg Category: Target version: Affected Puppet version: Keywords: backlog Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To post to this group, send email to puppet-bugs@googlegroups.com. To unsubscribe from this group, send email to puppet-bugs+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-bugs?hl=en.
[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Andrew Parker. Henrik Lindberg wrote: Nothingness is a quite complicated topic - here is how nothingness is handled in Scala: http://oldfashionedsoftware.com/2008/08/20/a-post-about-nothing/ The billion dollar mistake: http://qconlondon.com/london-2009/presentation/Null+References:+The+Billion+Dollar+Mistake In Puppet DSL, the semantics are quite `undef` as `undef` serves both as a symbolic nil, has no value, and as anti-matter (annihilates the expression). To keep sanity it is probably also required to modify the auto type conversion to boolean. Currently some type of emptiness (string is empty) is true, but not other forms. Is nil true or false? (IMO neither). Auto conversion to boolean is just a source of WAT. Without too much exploration, I think the best approach could be to introduce nil (or null) as a new Literal with the same semantics as Java or Ruby null/nil (i.e. somewhat ambiguous), as the much more sophisticated Nothingness definitions available in Scala is not all that useful in a semi-untyped language. I don't really like the idea of heading down the path that creates the incredible confusion in Javascript with null vs. undefined (http://saladwithsteve.com/2008/02/javascript-undefined-vs-null.html). Think first step towards doing something about this is to clearly define undef and nil and perform a thorough analysis. Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-74414 Author: Pieter van de Bruggen Status: Accepted Priority: Normal Assignee: Henrik Lindberg Category: Target version: Affected Puppet version: Keywords: backlog Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To post to this group, send email to puppet-bugs@googlegroups.com. To unsubscribe from this group, send email to puppet-bugs+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-bugs?hl=en.
[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Henrik Lindberg.
Andrew Parker wrote:
I don't really like the idea of heading down the path that creates the
incredible confusion in Javascript with null vs. undefined
(http://saladwithsteve.com/2008/02/javascript-undefined-vs-null.html).
I have been thinking more about this too - especially after looking at the
Scala way; although very precise, it is also completely confusing and overkill.
Having one value that is both antimatter and classic nil, does not work, but
having two is at the same time is both one too many, and not enough.
In fact, I really hate undef as an antimatter value that can be passed
around, and would prefer to get rid of that meaning completely in favor of a
straight forward classic nil sense. Big problem is that there is no
conditional fat comma. You are not allowed to do something like:
pre
file { 'title': if ($foo != undef) { mode = $foo}, owner = root }
/pre
Not would it be possible to easily support such syntax - it is just an example.
In all other cases, the syntax already allows passing a reasonable value, or no
value at all (i.e. function calls).
A conditional fat comma could be introduced with the meaning, set to 'nil'
(which we can continue to call 'undef') - it could look like this:
pre
file { 'title' : mode =? $foo, owner = root }
/pre
or some other clever way to express the operator. Oh, it could be done like
this:
pre
file { 'title' : (mode = $foo), owner = root }
/pre
The big advantage with this scheme is that it is totally clear where an undef
becomes antimatter / is a noop. User can decide to pass the undef as a value,
or use it to not set, and there is no confusion with two separate
nothingness values.
Bug #15329: Puppet lacks a proper undefined value
https://projects.puppetlabs.com/issues/15329#change-74450
Author: Pieter van de Bruggen
Status: Accepted
Priority: Normal
Assignee: Henrik Lindberg
Category:
Target version:
Affected Puppet version:
Keywords: backlog
Branch:
$y = undef
notice($y == ) # true
notice($x == $y) # true
notice($x == ) # true
Recent changes in the Puppet DSL made equality commutative (good!), but in
doing so broke work-arounds for actually testing for the difference between an
undefined and empty value. The most logical fix would be to equate Puppet's
`undef` with Ruby's `nil`.
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[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Henrik Lindberg.
Could also do something like
pre
file { 'foo': mode = $foo unless undef, owner = 'root' }
Bug #15329: Puppet lacks a proper undefined value
https://projects.puppetlabs.com/issues/15329#change-74522
Author: Pieter van de Bruggen
Status: Accepted
Priority: Normal
Assignee: Henrik Lindberg
Category:
Target version:
Affected Puppet version:
Keywords: backlog
Branch:
$y = undef
notice($y == ) # true
notice($x == $y) # true
notice($x == ) # true
Recent changes in the Puppet DSL made equality commutative (good!), but in
doing so broke work-arounds for actually testing for the difference between an
undefined and empty value. The most logical fix would be to equate Puppet's
`undef` with Ruby's `nil`.
--
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[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Henrik Lindberg. Nothingness is a quite complicated topic - here is how nothingness is handled in Scala: http://oldfashionedsoftware.com/2008/08/20/a-post-about-nothing/ In Puppet DSL, the semantics are quite `undef` as `undef` serves both as a symbolic nil, has no value, and as anti-matter (annihilates the expression). To keep sanity it is probably also required to modify the auto type conversion to boolean. Currently some type of emptiness (string is empty) is true, but not other forms. Is nil true or false? (IMO neither). Auto conversion to boolean is just a source of WAT. Without too much exploration, I think the best approach could be to introduce nil (or null) as a new Literal with the same semantics as Java or Ruby null/nil (i.e. somewhat ambiguous), as the much more sophisticated Nothingness definitions available in Scala is not all that useful in a semi-untyped language. Think first step towards doing something about this is to clearly define undef and nil and perform a thorough analysis. Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-72862 Author: Pieter van de Bruggen Status: Accepted Priority: High Assignee: Pieter van de Bruggen Category: Target version: Affected Puppet version: Keywords: Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To post to this group, send email to puppet-bugs@googlegroups.com. To unsubscribe from this group, send email to puppet-bugs+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-bugs?hl=en.
[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by eric sorenson. I've extracted all of the use cases and test code from the bugs linked above and put them into a 'modulepath' compatible git repository: https://github.com/ahpook/puppet-undef Hopefully this will be a useful, concrete starting point as we're trying to define what behaviour we want and making sure that things are consistent for the various things people want out of the DSL. Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-69626 Author: Pieter van de Bruggen Status: Accepted Priority: High Assignee: Pieter van de Bruggen Category: Target version: Affected Puppet version: Keywords: Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To post to this group, send email to puppet-bugs@googlegroups.com. To unsubscribe from this group, send email to puppet-bugs+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-bugs?hl=en.
[Puppet - Bug #15329] Puppet lacks a proper undefined value
Issue #15329 has been updated by Andrew Parker. My biggest concern around changing this is the possible impact on existing code. If anyone somehow relied on this insane behavior, then changes that make it much more straightforward might end up breaking all of that. We need to avoid that situation. So what is a way that we can get the semantics we want with a minimal (or at least very clearly understandable) break of existing code? Bug #15329: Puppet lacks a proper undefined value https://projects.puppetlabs.com/issues/15329#change-69468 Author: Pieter van de Bruggen Status: Accepted Priority: High Assignee: Pieter van de Bruggen Category: Target version: Affected Puppet version: Keywords: Branch: $y = undef notice($y == ) # true notice($x == $y) # true notice($x == ) # true Recent changes in the Puppet DSL made equality commutative (good!), but in doing so broke work-arounds for actually testing for the difference between an undefined and empty value. The most logical fix would be to equate Puppet's `undef` with Ruby's `nil`. -- You have received this notification because you have either subscribed to it, or are involved in it. To change your notification preferences, please click here: http://projects.puppetlabs.com/my/account -- You received this message because you are subscribed to the Google Groups Puppet Bugs group. To post to this group, send email to puppet-bugs@googlegroups.com. To unsubscribe from this group, send email to puppet-bugs+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/puppet-bugs?hl=en.
