Re: [Puppet Users] Re: leading double colons (::) for class instances
On 2019-01-08 15:16, jcbollinger wrote:
On Monday, January 7, 2019 at 3:37:46 PM UTC-6, Matt Zagrabelny wrote:
On Mon, Jan 7, 2019 at 3:31 PM Matt Zagrabelny > wrote:
Greetings puppet-users!
For many years I have been using the following convention for
including my classes:
class foo() {
include ::profile::bar
}
I know I don't need the leading double colon for including
profile::bar, but at one point in time I thought it may have
been a best practice or it would help prevent some sort of
future pain point.
Is that still true? Was I ever correct?
Needed to spend 30 more seconds reading before hitting send. Sorry
for the noise!
https://github.com/voxpupuli/puppet-lint-absolute_classname-check/issues/3
Thanks for any additional feedback!
I observe that the voxpupuli thread slightly downlplays the scope of the
issue as it affected Puppet 3. Puppet's (long since removed) relative
name resolution scheme looked not just at the namespace in which the
name was used, as the voxpupuli discussion seems to suggest, but also at
every ancestor namespace, in order, until ultimately reaching top
scope. I'm not sure where to find P3 docs any longer, but this behavior
is summarized in the description of PUP-121
, the issue for removing
that behavior.
That only rarely bit people, but it bit enough people, often enough,
that for a time it was considered best practice to always use
fully-qualified names (which is effectively what the `::` prefix
produces). But Puppet, Inc. decided that the negatives of relative name
resolution outweighed the positives, including the positive of
minimizing breaking changes, so relative name resolution was removed in
Puppet 4. Nowadays, the :: prefix is accepted for backwards
compatibility, but it conveys no additional meaning.
Adding to what John said above:
There is no additional meaning for class names when it starts with '::',
it does however make a difference when referencing variables. If a
variable contains '::' (anywhere) it is always taken as an absolute
reference starting from topscope. Thus something like '$::x' is the
topscope $x, a '$x' is a local, inherited or topscope variable 'x', and
'$x::y' and '$::x::y' are exactly the same thing.
- Henrik
John
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[Puppet Users] Re: leading double colons (::) for class instances
On Monday, January 7, 2019 at 3:37:46 PM UTC-6, Matt Zagrabelny wrote:
>
>
>
> On Mon, Jan 7, 2019 at 3:31 PM Matt Zagrabelny > wrote:
>
>> Greetings puppet-users!
>>
>> For many years I have been using the following convention for including
>> my classes:
>>
>> class foo() {
>> include ::profile::bar
>> }
>>
>> I know I don't need the leading double colon for including profile::bar,
>> but at one point in time I thought it may have been a best practice or it
>> would help prevent some sort of future pain point.
>>
>> Is that still true? Was I ever correct?
>>
>>
> Needed to spend 30 more seconds reading before hitting send. Sorry for the
> noise!
>
> https://github.com/voxpupuli/puppet-lint-absolute_classname-check/issues/3
>
> Thanks for any additional feedback!
>
>
I observe that the voxpupuli thread slightly downlplays the scope of the
issue as it affected Puppet 3. Puppet's (long since removed) relative name
resolution scheme looked not just at the namespace in which the name was
used, as the voxpupuli discussion seems to suggest, but also at every
ancestor namespace, in order, until ultimately reaching top scope. I'm not
sure where to find P3 docs any longer, but this behavior is summarized in
the description of PUP-121 ,
the issue for removing that behavior.
That only rarely bit people, but it bit enough people, often enough, that
for a time it was considered best practice to always use fully-qualified
names (which is effectively what the `::` prefix produces). But Puppet,
Inc. decided that the negatives of relative name resolution outweighed the
positives, including the positive of minimizing breaking changes, so
relative name resolution was removed in Puppet 4. Nowadays, the :: prefix
is accepted for backwards compatibility, but it conveys no additional
meaning.
John
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[Puppet Users] Re: leading double colons (::) for class instances
On Mon, Jan 7, 2019 at 3:31 PM Matt Zagrabelny wrote:
> Greetings puppet-users!
>
> For many years I have been using the following convention for including my
> classes:
>
> class foo() {
> include ::profile::bar
> }
>
> I know I don't need the leading double colon for including profile::bar,
> but at one point in time I thought it may have been a best practice or it
> would help prevent some sort of future pain point.
>
> Is that still true? Was I ever correct?
>
>
Needed to spend 30 more seconds reading before hitting send. Sorry for the
noise!
https://github.com/voxpupuli/puppet-lint-absolute_classname-check/issues/3
Thanks for any additional feedback!
-m
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