Formula vs Magritte

> Le vendredi 19 mars 2010 à 19:08 -0200, Germán Arduino a écrit :
>> I would like to know the main differences/features between Formula and Magritte.
>
> Hi German,
>
> Sorry for the late answer. Formula and Magritte are very different.
> First of all, Formula isn't about meta descriptions at all, but just
> about building validated forms with ease.
>
> If you need to describe your model for something else than building UI,
> I would consider using Magritte, because I think it's very powerful, and
> it has some interesting extensions.
>
> Else I would use Formula, because its design is much simpler than
> Magritte, and it's a lot easier to customize.
>
> If you need examples of Formula, you can read this blog post:
> http://smalltalk.gnu.org/blog/nico/formula-building-nice-validated-forms-iliad-ease
>
> Cheers!
>
> Nico
>

> Le lundi 22 mars 2010 à 17:02 -0300, Germán Arduino a écrit :
>> Thanks by the response Nico.
>>
>> That means that if, for example, I wants to validate the same field in
>> two different forms, with Formula I will need to codify the validation
>> twice?
>
> Not necessarily. For example, you can have a formula to create and edit
> users, and select fields you want for a specific context :
>
> userFormula [
>        | formula |
>        formula := ILFormula on: self user.
>        (formula inputOn: #username)
>                label: 'Username'.
>        (formula inputOn: #fullName)
>                label: 'Full name'.
>        (formula inputOn: #password)
>                label: 'Password'.
>        ...
>        ^formula
> ]
>
> loginFormula [
>        ^self userFormula select: [:each |
>                #(#username #password) includes: each key]
> ]
>
>
> Another way to do it for complex forms where you have lots of fields
> would be to use custom attributes in fields:
>
> userFormula [
>        | formula |
>        formula := ILFormula on: self user.
>        (formula inputOn: #username)
>                attributeAt: #login put: true.
>                label: 'Username'.
>        (formula inputOn: #fullName)
>                label: 'Full name'.
>        (formula inputOn: #password)
>                attributeAt: #login put: true.
>                label: 'Password'.
>        ...
>        ^formula
> ]
>
> loginFormula [
>        ^self userFormula select: [:each |
>                (each attributeAt: #login) = true]
> ]
>
>
>>
>> And another question, Formula does nothing related with relationships
>> between objects, right?
>
> No, it doesn't, but I never found the default implementation in Magritte
> very useful anyway. Still, Formula allows you to deal with collections,
> so you can easily set relationships. The example above deals the
> relationship between users and user groups:
>
> userFormula [
>        | formula |
>        formula := ILFormula on: self user.
>        "Set the group this user belongs to"
>        (formula selectOn: #group)
>                options: self allGroups "A collection of group objects"
>                labels: [:group | group name].
>        ...
>        ^formula
> ]
>
> For one to many or many to many relationships, (for example, a group has
> many users), you can do it this way:
>
> groupFormula [
>        | formula |
>        formula := ILFormula on: self group.
>        (formula selectOn: #users)
>                "Allow several users to be in this group"
>                multiple: true;
>                options: self allUsers;
>                labels: [:user | user fullName].
>        ...
>        ^formula
> ]
>
>
> HTH,
>
> Nico
>