configobj-develop

[Configobj-develop] Problem with list values

[Arve K. <arv...@gm...>]

Hi
I have a problem with configobj/validate (in general a great combination!)
that keeps cropping up. If I forget to include a comma (',') when defining a
list value in my configuration file, it is translated into a string (even
though its specified type is 'list'). The fix is simply to add a comma to
the end of the configuration value. Is there any reason for this behaviour?
I find it rather painful since I have to check in my own code whether
supposed list values from configobj are actually lists or strings.

Arve

Re: [Configobj-develop] Problem with list values

[Michael F. <fuz...@vo...>]

Arve Knudsen wrote:
> Hi
> I have a 
> problem with configobj/validate (in general a great combination!) that 
> keeps cropping up. If I forget to include a comma (',') when defining 
> a list value in my configuration file, it is translated into a string 
> (even though its specified type is 'list'). The fix is simply to add a 
> comma to the end of the configuration value. Is there any reason for 
> this behaviour? I find it rather painful since I have to check in my 
> own code whether supposed list values from configobj are actually 
> lists or strings.
Can you post a minimal config and validation file that illustrates the 
problem, and I'll look at it.

In general, lists without commas aren't lists. :-)

I guess if an item is explicitly specified as a list then coercing a 
string into a single member list *sounds* like the right behaviour 
(rather than raising an error). Anyone else have any opinions?

Michael
http://www.voidspace.org.uk/python/index.shtml

>
> Arve
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Re: [Configobj-develop] Problem with list values

[Arve K. <arv...@gm...>]

On 5/14/07, Michael Foord <fuz...@vo...> wrote:
>
> Arve Knudsen wrote:
> > Hi
> > I have a
> > problem with configobj/validate (in general a great combination!) that
> > keeps cropping up. If I forget to include a comma (',') when defining
> > a list value in my configuration file, it is translated into a string
> > (even though its specified type is 'list'). The fix is simply to add a
> > comma to the end of the configuration value. Is there any reason for
> > this behaviour? I find it rather painful since I have to check in my
> > own code whether supposed list values from configobj are actually
> > lists or strings.
> Can you post a minimal config and validation file that illustrates the
> problem, and I'll look at it.


# Config
values = val1

# Reading config in Python
import configobj, validate

conf = configobj.ConfigObj("test.cfg", configspec={"values": "list"})
vdt = validate.Validator()
conf.validate(vdt)
# The configuration now contains a string value for parameter "values"

In general, lists without commas aren't lists. :-)


Yes, that much is obvious.

I guess if an item is explicitly specified as a list then coercing a
> string into a single member list *sounds* like the right behaviour
> (rather than raising an error). Anyone else have any opinions?
>

I would like this behaviour, otherwise the validation should raise an error
instead of silently returning a string when a list was specified in the
validation schema.

Thanks,
Arve

Re: [Configobj-develop] Problem with list values

[Michael F. <fuz...@vo...>]

Thanks Arve - I'll look at this. Anyone else have an opinion on the 
'raise an error or coerce to list' question ?

Michael

Arve Knudsen wrote:
>
>
> On 5/14/07, *Michael Foord* <fuz...@vo... 
> <mailto:fuz...@vo...>> wrote:
>
>     Arve Knudsen wrote:
>     > Hi
>     > I have a
>     > problem with configobj/validate (in general a great
>     combination!) that
>     > keeps cropping up. If I forget to include a comma (',') when
>     defining
>     > a list value in my configuration file, it is translated into a
>     string
>     > (even though its specified type is 'list'). The fix is simply to
>     add a
>     > comma to the end of the configuration value. Is there any reason for
>     > this behaviour? I find it rather painful since I have to check
>     in my
>     > own code whether supposed list values from configobj are actually
>     > lists or strings.
>     Can you post a minimal config and validation file that illustrates the
>     problem, and I'll look at it.
>
>
> # Config
> values = val1
>
> # Reading config in Python
> import configobj, validate
>
> conf = configobj.ConfigObj("test.cfg", configspec={"values": "list"})
> vdt = validate.Validator ()
> conf.validate(vdt)
> # The configuration now contains a string value for parameter "values"
>
>     In general, lists without commas aren't lists. :-)
>
>
> Yes, that much is obvious. 
>
>     I guess if an item is explicitly specified as a list then coercing a
>     string into a single member list *sounds* like the right behaviour
>     (rather than raising an error). Anyone else have any opinions?
>
>
> I would like this behaviour, otherwise the validation should raise an 
> error instead of silently returning a string when a list was specified 
> in the validation schema.
>
> Thanks,
> Arve
>
> ------------------------------------------------------------------------
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by DB2 Express
> Download DB2 Express C - the FREE version of DB2 express and take
> control of your XML. No limits. Just data. Click to get it now.
> http://sourceforge.net/powerbar/db2/
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>
> _______________________________________________
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> https://lists.sourceforge.net/lists/listinfo/configobj-develop
>   

Re: [Configobj-develop] Problem with list values

[Nicola L. <ni...@te...>]

Michael Foord wrote:
>> I would like this behaviour, otherwise the validation should raise an
>> error instead of silently returning a string when a list was specified
>> in the validation schema.

> Thanks Arve - I'll look at this. Anyone else have an opinion on the 
> 'raise an error or coerce to list' question ?

I don't need to remind you the timeless lesson of the ages before us: ;-)

"Explicit is better than implicit.
...
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess."

There is an ambiguity in *meaning* here, so definitely raise an error.


-- 
Nicola Larosa - http://www.tekNico.net/

That's what *professionals* do. They are always learning. Always. Because
nothing you learn about what's "the best" or "the worst" stays the same
forever. And if you don't keep up, you're just falling behind.
 -- Phillip J. Eby, January 2007

Re: [Configobj-develop] Problem with list values

[Arve K. <arv...@gm...>]

On 5/15/07, Nicola Larosa <ni...@te...> wrote:
>
> Michael Foord wrote:
> >> I would like this behaviour, otherwise the validation should raise an
> >> error instead of silently returning a string when a list was specified
> >> in the validation schema.
>
> > Thanks Arve - I'll look at this. Anyone else have an opinion on the
> > 'raise an error or coerce to list' question ?
>
> I don't need to remind you the timeless lesson of the ages before us: ;-)
>
> "Explicit is better than implicit.
> ...
> Errors should never pass silently.
> Unless explicitly silenced.
> In the face of ambiguity, refuse the temptation to guess."
>
> There is an ambiguity in *meaning* here, so definitely raise an error.


I don't see any big _practical_ benefit of this level of strictness,
especially since this affects users (non-programmers) directly. I find it
more user friendly to accept strings for single-value lists, since the only
difference is a comma at the end anyhow. I'd say this behaviour amounts to
the least surprise, although others may disagree.

Arve

Re: [Configobj-develop] Problem with list values

[Arve K. <arv...@gm...>]

Just checking if anything is being done about this issue?

Arve

On 5/16/07, Michael Foord <ar...@vo...> wrote:
>
> Nicola Larosa wrote:
> > Michael Foord wrote:
> >
> >>> I would like this behaviour, otherwise the validation should raise an
> >>> error instead of silently returning a string when a list was specified
> >>> in the validation schema.
> >>>
> >
> >
> >> Thanks Arve - I'll look at this. Anyone else have an opinion on the
> >> 'raise an error or coerce to list' question ?
> >>
> >
> > I don't need to remind you the timeless lesson of the ages before us:
> ;-)
> >
> > "Explicit is better than implicit.
> > ...
> > Errors should never pass silently.
> > Unless explicitly silenced.
> > In the face of ambiguity, refuse the temptation to guess."
> >
> > There is an ambiguity in *meaning* here, so definitely raise an error.
> >
> I'm still slightly reluctant, if the entry is meant to be a list then a
> single entry is valid and we're debating syntax.
>
> On the other hand there *is* a potential cause for confusion - so at
> least an error will signal where the problem is. I think this is
> probably the right thing to do.
>
> There is possibly also an issue with empty values and empty lists as well.
>
> I'll look into it.
>
> Michael
>
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by DB2 Express
> Download DB2 Express C - the FREE version of DB2 express and take
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Re: [Configobj-develop] Problem with list values

[Michael F. <ar...@vo...>]

Nicola Larosa wrote:
> Michael Foord wrote:
>   
>>> I would like this behaviour, otherwise the validation should raise an
>>> error instead of silently returning a string when a list was specified
>>> in the validation schema.
>>>       
>
>   
>> Thanks Arve - I'll look at this. Anyone else have an opinion on the 
>> 'raise an error or coerce to list' question ?
>>     
>
> I don't need to remind you the timeless lesson of the ages before us: ;-)
>
> "Explicit is better than implicit.
> ...
> Errors should never pass silently.
> Unless explicitly silenced.
> In the face of ambiguity, refuse the temptation to guess."
>
> There is an ambiguity in *meaning* here, so definitely raise an error.
>   
I'm still slightly reluctant, if the entry is meant to be a list then a 
single entry is valid and we're debating syntax.

On the other hand there *is* a potential cause for confusion - so at 
least an error will signal where the problem is. I think this is 
probably the right thing to do.

There is possibly also an issue with empty values and empty lists as well.

I'll look into it.

Michael

Re: [Configobj-develop] Problem with list values

[Michael F. <fuz...@vo...>]

Arve Knudsen wrote:
> Just checking if anything is being done about this issue?

I'm afraid I haven't had a chance to look at this yet. :-(

It is still 'on my list' though, and everything does get done eventually...

Michael


>
> Arve
>
> On 5/16/07, *Michael Foord* <ar...@vo... 
> <mailto:ar...@vo...>> wrote:
>
>     Nicola Larosa wrote:
>     > Michael Foord wrote:
>     >
>     >>> I would like this behaviour, otherwise the validation should
>     raise an
>     >>> error instead of silently returning a string when a list was
>     specified
>     >>> in the validation schema.
>     >>>
>     >
>     >
>     >> Thanks Arve - I'll look at this. Anyone else have an opinion on
>     the
>     >> 'raise an error or coerce to list' question ?
>     >>
>     >
>     > I don't need to remind you the timeless lesson of the ages
>     before us: ;-)
>     >
>     > "Explicit is better than implicit.
>     > ...
>     > Errors should never pass silently.
>     > Unless explicitly silenced.
>     > In the face of ambiguity, refuse the temptation to guess."
>     >
>     > There is an ambiguity in *meaning* here, so definitely raise an
>     error.
>     >
>     I'm still slightly reluctant, if the entry is meant to be a list
>     then a
>     single entry is valid and we're debating syntax.
>
>     On the other hand there *is* a potential cause for confusion - so at
>     least an error will signal where the problem is. I think this is
>     probably the right thing to do.
>
>     There is possibly also an issue with empty values and empty lists
>     as well.
>
>     I'll look into it.
>
>     Michael
>
>
>
>     -------------------------------------------------------------------------
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>
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Re: [Configobj-develop] Problem with list values

[Arve K. <arv...@gm...>]

On 8/22/07, Michael Foord <fuz...@vo...> wrote:
>
> Arve Knudsen wrote:
> > Just checking if anything is being done about this issue?
>
> I'm afraid I haven't had a chance to look at this yet. :-(
>
> It is still 'on my list' though, and everything does get done
> eventually...


OK.

Arve


>
> > Arve
> >
> > On 5/16/07, *Michael Foord* <ar...@vo...
> > <mailto:ar...@vo...>> wrote:
> >
> >     Nicola Larosa wrote:
> >     > Michael Foord wrote:
> >     >
> >     >>> I would like this behaviour, otherwise the validation should
> >     raise an
> >     >>> error instead of silently returning a string when a list was
> >     specified
> >     >>> in the validation schema.
> >     >>>
> >     >
> >     >
> >     >> Thanks Arve - I'll look at this. Anyone else have an opinion on
> >     the
> >     >> 'raise an error or coerce to list' question ?
> >     >>
> >     >
> >     > I don't need to remind you the timeless lesson of the ages
> >     before us: ;-)
> >     >
> >     > "Explicit is better than implicit.
> >     > ...
> >     > Errors should never pass silently.
> >     > Unless explicitly silenced.
> >     > In the face of ambiguity, refuse the temptation to guess."
> >     >
> >     > There is an ambiguity in *meaning* here, so definitely raise an
> >     error.
> >     >
> >     I'm still slightly reluctant, if the entry is meant to be a list
> >     then a
> >     single entry is valid and we're debating syntax.
> >
> >     On the other hand there *is* a potential cause for confusion - so at
> >     least an error will signal where the problem is. I think this is
> >     probably the right thing to do.
> >
> >     There is possibly also an issue with empty values and empty lists
> >     as well.
> >
> >     I'll look into it.
> >
> >     Michael
> >
> >
> >
> >
> -------------------------------------------------------------------------
> >     This SF.net email is sponsored by DB2 Express
> >     Download DB2 Express C - the FREE version of DB2 express and take
> >     control of your XML. No limits. Just data. Click to get it now.
> >     http://sourceforge.net/powerbar/db2/
> >     _______________________________________________
> >     Configobj-develop mailing list
> >     Con...@li...
> >     <mailto:Con...@li...>
> >     https://lists.sourceforge.net/lists/listinfo/configobj-develop
> >
> >
> > ------------------------------------------------------------------------
> >
> >
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> > Still grepping through log files to find problems?  Stop.
> > Now Search log events and configuration files using AJAX and a browser.
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> >
>
>
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