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Posted to dev@ofbiz.apache.org by Adrian Crum <ad...@yahoo.com> on 2009/11/11 04:40:54 UTC
Discussion: User-Defined Java Data Types In The Framework
I first started thinking of this idea in a Jira issue:
https://issues.apache.org/jira/browse/OFBIZ-3125
I thought it would be easy to extend the framework to support a new Java object type (or class). I wanted to be able to pass around a TimeDuration instance in services, mini-lang, screen widgets, etc. I thought it would be easy. It wasn't.
Those framework artifacts convert Java objects from one type to another using the ObjectType class. I had to make changes to a huge monolithic if-else-if block in that class. Then I had to modify some code in the Entity Engine. I couldn't get the Entity Engine to support the TimeDuration class because of two monolithic switch statements where Java data types are mapped to integers, but not in a centralized way.
I stopped trying to wedge the TimeDuration class into inflexible code, and instead started working on making the code more flexible.
I replaced the monolithic if-else-if block in ObjectType with polymorphism. Now components can extend the framework with their own Java object type conversions.
I still need to work on the Entity Engine. I would like to replace its monolithic conditionals with the new conversion code. Before I get started, I wanted to present the idea to the community to see if there were any objections.
The goal is to make it easier for developers to add new Java data types to the framework. I see this as a big benefit to writing OFBiz add-ons or customizations.
What do you think?
-Adrian
Re: Discussion: User-Defined Java Data Types In The Framework
Posted by Adrian Crum <ad...@hlmksw.com>.
Harmeet and David,
Thank you for the comments! I agree that the ability I proposed could be
taken too far and eventually make mini-language harder to understand.
But at the same time, when a real need arrives to add a new type, it
should be easier to implement.
David - this started with the need to use TimeDuration in the framework.
Adding support for it results in much simpler script. Try this out in
any screen widget screen:
<actions>
<set field="durationLong" value="6000" type="Long"/>
<set field="duration" from-field="durationLong" type="TimeDuration"/>
</actions>
<widgets>
<container style="h2"><label text="${duration}"/></container>
</widgets>
-Adrian
David E Jones wrote:
>
> Thanks for your comments Harmeet.
>
> My main concern was that it makes these various bits of code bigger and
> more complex, and to balance that I'm wondering what the need is... ie
> what benefit comes from it? I know there are theoretical benefits like
> "at some point someone might want to do something different" but that is
> highly hypothetical, and in theory one can put an infinite amount of
> effort into hypothetical needs and never actually solve any real problems.
>
> Anyway, your point is good Harmeet that this could actually introduce a
> weak point where customizers could create more issues.
>
> I suppose my problem is that I've just never run into a need for
> something like this... so I find it pretty low on my "care about" meter,
> and if Adrian wants to go for it then great! ..and hopefully it will do
> more good than harm should it ever do much of either.
>
> -David
>
>
> On Nov 10, 2009, at 9:58 PM, Harmeet Bedi wrote:
>
>> I think TimeDuration is a useful base type. It is something that
>> exists in .NET system package (TimeSpan class) but has not been given
>> as much importance in java land. I personally prefer name TimeSpan
>> over TimeDuration.
>> I think very nice to replace if-then-else with OO equivalents. Ofbiz
>> has too much if then else.. Makes things harder to extend.
>>
>>
>> On a note of caution. Currently system has very few fundamental types
>> and everything has to be built from those few blocks. It keeps the
>> foundation very simple.
>> Custom data types can be powerful but it could be bad if different
>> apps start adding their own types and building on that. Maybe this is
>> something that should be reasonably easy to add at system level but
>> users should not be encouraged to add types.
>>
>> Harmeet
>>
>> ----- Original Message -----
>> From: "Adrian Crum" <ad...@yahoo.com>
>> To: dev@ofbiz.apache.org
>> Sent: Tuesday, November 10, 2009 10:40:54 PM GMT -05:00 US/Canada Eastern
>> Subject: Discussion: User-Defined Java Data Types In The Framework
>>
>> I first started thinking of this idea in a Jira issue:
>>
>> https://issues.apache.org/jira/browse/OFBIZ-3125
>>
>> I thought it would be easy to extend the framework to support a new
>> Java object type (or class). I wanted to be able to pass around a
>> TimeDuration instance in services, mini-lang, screen widgets, etc. I
>> thought it would be easy. It wasn't.
>>
>> Those framework artifacts convert Java objects from one type to
>> another using the ObjectType class. I had to make changes to a huge
>> monolithic if-else-if block in that class. Then I had to modify some
>> code in the Entity Engine. I couldn't get the Entity Engine to support
>> the TimeDuration class because of two monolithic switch statements
>> where Java data types are mapped to integers, but not in a centralized
>> way.
>>
>> I stopped trying to wedge the TimeDuration class into inflexible code,
>> and instead started working on making the code more flexible.
>>
>> I replaced the monolithic if-else-if block in ObjectType with
>> polymorphism. Now components can extend the framework with their own
>> Java object type conversions.
>>
>> I still need to work on the Entity Engine. I would like to replace its
>> monolithic conditionals with the new conversion code. Before I get
>> started, I wanted to present the idea to the community to see if there
>> were any objections.
>>
>> The goal is to make it easier for developers to add new Java data
>> types to the framework. I see this as a big benefit to writing OFBiz
>> add-ons or customizations.
>>
>> What do you think?
>>
>> -Adrian
>>
>>
>>
>>
>
>
Re: Discussion: User-Defined Java Data Types In The Framework
Posted by Adrian Crum <ad...@hlmksw.com>.
David E Jones wrote:
> My main concern was that it makes these various bits of code bigger and
> more complex
That's true. In Fowler's Replace Conditional With Polymorphism example,
the ten line switch statement is replaced by an abstract class and three
subclasses. It's more code, but it's easier to build upon.
-Adrian
Re: Discussion: User-Defined Java Data Types In The Framework
Posted by David E Jones <de...@me.com>.
Thanks for your comments Harmeet.
My main concern was that it makes these various bits of code bigger
and more complex, and to balance that I'm wondering what the need
is... ie what benefit comes from it? I know there are theoretical
benefits like "at some point someone might want to do something
different" but that is highly hypothetical, and in theory one can put
an infinite amount of effort into hypothetical needs and never
actually solve any real problems.
Anyway, your point is good Harmeet that this could actually introduce
a weak point where customizers could create more issues.
I suppose my problem is that I've just never run into a need for
something like this... so I find it pretty low on my "care about"
meter, and if Adrian wants to go for it then great! ..and hopefully it
will do more good than harm should it ever do much of either.
-David
On Nov 10, 2009, at 9:58 PM, Harmeet Bedi wrote:
> I think TimeDuration is a useful base type. It is something that
> exists in .NET system package (TimeSpan class) but has not been
> given as much importance in java land. I personally prefer name
> TimeSpan over TimeDuration.
> I think very nice to replace if-then-else with OO equivalents. Ofbiz
> has too much if then else.. Makes things harder to extend.
>
>
> On a note of caution. Currently system has very few fundamental
> types and everything has to be built from those few blocks. It keeps
> the foundation very simple.
> Custom data types can be powerful but it could be bad if different
> apps start adding their own types and building on that. Maybe this
> is something that should be reasonably easy to add at system level
> but users should not be encouraged to add types.
>
> Harmeet
>
> ----- Original Message -----
> From: "Adrian Crum" <ad...@yahoo.com>
> To: dev@ofbiz.apache.org
> Sent: Tuesday, November 10, 2009 10:40:54 PM GMT -05:00 US/Canada
> Eastern
> Subject: Discussion: User-Defined Java Data Types In The Framework
>
> I first started thinking of this idea in a Jira issue:
>
> https://issues.apache.org/jira/browse/OFBIZ-3125
>
> I thought it would be easy to extend the framework to support a new
> Java object type (or class). I wanted to be able to pass around a
> TimeDuration instance in services, mini-lang, screen widgets, etc. I
> thought it would be easy. It wasn't.
>
> Those framework artifacts convert Java objects from one type to
> another using the ObjectType class. I had to make changes to a huge
> monolithic if-else-if block in that class. Then I had to modify some
> code in the Entity Engine. I couldn't get the Entity Engine to
> support the TimeDuration class because of two monolithic switch
> statements where Java data types are mapped to integers, but not in
> a centralized way.
>
> I stopped trying to wedge the TimeDuration class into inflexible
> code, and instead started working on making the code more flexible.
>
> I replaced the monolithic if-else-if block in ObjectType with
> polymorphism. Now components can extend the framework with their own
> Java object type conversions.
>
> I still need to work on the Entity Engine. I would like to replace
> its monolithic conditionals with the new conversion code. Before I
> get started, I wanted to present the idea to the community to see if
> there were any objections.
>
> The goal is to make it easier for developers to add new Java data
> types to the framework. I see this as a big benefit to writing OFBiz
> add-ons or customizations.
>
> What do you think?
>
> -Adrian
>
>
>
>
Re: Discussion: User-Defined Java Data Types In The Framework
Posted by Harmeet Bedi <ha...@gmail.com>.
I think TimeDuration is a useful base type. It is something that exists in .NET system package (TimeSpan class) but has not been given as much importance in java land. I personally prefer name TimeSpan over TimeDuration.
I think very nice to replace if-then-else with OO equivalents. Ofbiz has too much if then else.. Makes things harder to extend.
On a note of caution. Currently system has very few fundamental types and everything has to be built from those few blocks. It keeps the foundation very simple.
Custom data types can be powerful but it could be bad if different apps start adding their own types and building on that. Maybe this is something that should be reasonably easy to add at system level but users should not be encouraged to add types.
Harmeet
----- Original Message -----
From: "Adrian Crum" <ad...@yahoo.com>
To: dev@ofbiz.apache.org
Sent: Tuesday, November 10, 2009 10:40:54 PM GMT -05:00 US/Canada Eastern
Subject: Discussion: User-Defined Java Data Types In The Framework
I first started thinking of this idea in a Jira issue:
https://issues.apache.org/jira/browse/OFBIZ-3125
I thought it would be easy to extend the framework to support a new Java object type (or class). I wanted to be able to pass around a TimeDuration instance in services, mini-lang, screen widgets, etc. I thought it would be easy. It wasn't.
Those framework artifacts convert Java objects from one type to another using the ObjectType class. I had to make changes to a huge monolithic if-else-if block in that class. Then I had to modify some code in the Entity Engine. I couldn't get the Entity Engine to support the TimeDuration class because of two monolithic switch statements where Java data types are mapped to integers, but not in a centralized way.
I stopped trying to wedge the TimeDuration class into inflexible code, and instead started working on making the code more flexible.
I replaced the monolithic if-else-if block in ObjectType with polymorphism. Now components can extend the framework with their own Java object type conversions.
I still need to work on the Entity Engine. I would like to replace its monolithic conditionals with the new conversion code. Before I get started, I wanted to present the idea to the community to see if there were any objections.
The goal is to make it easier for developers to add new Java data types to the framework. I see this as a big benefit to writing OFBiz add-ons or customizations.
What do you think?
-Adrian