[wildfly-dev] CLI batches in control flow blocks

[Tom Fonteyne]

IMHO.... you cannot use if/then in batches anyhow, e.g:

batch
...
if ...
...
then
...
fi
...
run-batch

fails. So the use of if/then was of very limited use anyhow.

Having multi-level batch would be ideal.
Removing auto-batch from if/then blocks would at least allow batches 
"around" them to work properly which would be a big win anyhow.

just my £0.02 of course
Tom


On 04/09/15 06:55, Alexey Loubyansky wrote:
> On 09/04/2015 12:10 AM, Brian Stansberry wrote:
>> The risk is this can break existing scripts, which we've sought to
>> avoid. A couple breakage scenarios:
>>
>> 1) Step 1 needs to happen in a batch with Step 2; now it won't so the
>> script breaks.
>> 2) Step 1 works but for some reason Step 2 fails, and now Step 1 isn't
>> rolled back.
>>
>> The first one is more likely, but the second one is a bigger concern, as
>> the user may not be aware Step 1 wasn't rolled back.
>>
>> Do you have any sense of how common either of those scenarios would be?
> Unfortunately, no. I don't get much feedback on this except for created
> issues that I referenced.
> I wouldn't bring it up unless this wasn't a major version release, of
> course.
>
>> Below are bad ideas that I wrote down and then thought better of, but
>> I'll send them in case it sparks a thought.
>>
>> I. Since there is already logic for dropping out of the batch for things
>> like cd, ls, could it be modified as follows?
>>
>> a) Close any current batch and execute that batch.
>> b) Execute the cd, ls, etc
>> c) Proceed, and if the next statement isn't a cd, ls etc, start a new batch.
>>
>> That seems like a better semantic for cd and ls anyway.
> I don't think so. The batch mode is also a composition/editing mode. cd
> and ls are useful when writing commands/operations that should be added
> to the batch. Imagine editing a batch and wishing to cd before entering
> next lines. That won't be possible without explicit holback-batch, cd
> and then batch again. That would be inconvenient.
>
>> With that, reload and shutdown can be treated the same as cd, ls.
> For reload and shutdown that does seem to make sense. So, a possible
> alternative is making them exceptions.
>
>> Why a bad idea? Doing it as I suggest has the same two drawbacks as
>> requiring the user to declare the batch. :( Just perhaps less likely to
>> occur.
>>
>> II. Is an --auto-batch=true|false param to if/else/try/catch/finally
>> possible? Why a bad idea? To solve the breakage problem it would need to
>> be 'true' by default, thus forcing users forever to declare that they
>> want the non-broken mode, *plus* they have to declare the batches.
> As a param to if/else/try/catch/finally this doesn't make sense to me.
> Because then the user could simply explicitly start bodies with batch.
> This kind of argument could make sense as a launching script argument
> for the whole cli session, imo.
>
> Thanks,
> Alexey
>
>>
>> On 9/3/15 10:42 AM, Alexey Loubyansky wrote:
>>> Hello everyone,
>>>
>>> I've been thinking about changing how the bodies of if-else and
>>> try-catch-finally are treated by the CLI.
>>>
>>> Up until now every control flow block (i.e. between if and else, between
>>> else and end-if, etc) was executed as a batch. So, when a block was
>>> selected for the execution, the CLI would enter the batch mode and
>>> proceed adding operations (and commands translated to operations) to it.
>>> If a command can't be translated to an operation, it would be executed
>>> outside the batch immediately (that's done for commands like cd, ls,
>>> etc). After the last line of the body processed, the batch (if not
>>> empty) is executed.
>>>
>>> But this doesn't work when mixing operations with shutdown or reload
>>> commands (they do translate to operations but they have additional logic
>>> related to re-connecting). shutdown/reload will be executed outside the
>>> batch and before the batch is complete.
>>>
>>> Currently open issues for this
>>> https://issues.jboss.org/browse/WFCORE-876
>>> https://issues.jboss.org/browse/WFCORE-533
>>>
>>> So, I think it was a mistake to execute the bodies of control flow
>>> blocks as batches. It would be better leave them as usual sequences of
>>> command lines and if the user wants a batch, he/she could add batch
>>> command explicitly.
>>>
>>> I wanted to ask for opinions. Could we make this change in WildFly 10?
>>>
>>> Thanks,
>>> Alexey
>>> _______________________________________________
>>> wildfly-dev mailing list
>>> wildfly-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/wildfly-dev
>>>
>>
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-- 
Tom R. Fonteyne - SSME
Red Hat - UK
EMEA GSS SEG-Middleware